阅读说明：本技术 检测装置和包括检测装置的车载系统 (Detection device and on-vehicle system including detection device ) 是由 川上智朗 于 2019-01-07 设计创作，主要内容包括：提供了一种检测装置,该检测装置包括：光源,该光源发射照明光束；光接收元件,该光接收元件接收来自物体的反射光束；偏振单元,该偏转单元使照明光束朝着物体偏转以扫描物体并且使反射光束朝着光接收元件偏转；分离单元,该分离单元允许来自光源的照明光束朝着偏转单元前进并且允许来自偏转单元的反射光束朝着光接收元件前进；以及第一望远镜,该第一望远镜增加被偏转单元偏转的照明光束的直径并且减小来自物体的反射光束的直径,其中偏转单元被布置为使得防止在偏转单元的扫描范围内的中心视角处的照明光束的主光线的光路与第一望远镜的光轴重合。(There is provided a detection apparatus comprising: a light source emitting an illumination beam; a light receiving element that receives a reflected light beam from the object; a polarizing unit that deflects the illumination light beam toward the object to scan the object and deflects the reflected light beam toward the light receiving element; a separation unit that allows the illumination light beam from the light source to proceed toward the deflection unit and allows the reflected light beam from the deflection unit to proceed toward the light receiving element; and a first telescope that increases a diameter of the illumination beam deflected by the deflection unit and decreases a diameter of a reflected beam from the object, wherein the deflection unit is arranged such that an optical path of a principal ray of the illumination beam at a central view angle within a scanning range of the deflection unit is prevented from coinciding with an optical axis of the first telescope.)

1. A detection device, comprising:

a light source configured to emit an illumination beam;

a light receiving element configured to receive a reflected light beam from an object;

a deflection unit configured to deflect the illumination light beam toward the object so as to scan the object, and configured to deflect the reflected light beam toward the light receiving element;

a separation unit configured to allow the illumination light beam from the light source to proceed toward the deflection unit, and configured to allow the reflected light beam from the deflection unit to proceed toward the light receiving element; and

a first telescope configured to increase a diameter of the illumination beam deflected by the deflection unit and configured to decrease a diameter of a reflected beam from the object,

wherein the deflection unit is arranged such that an optical path of a chief ray of the illumination beam at a central view angle within a scanning range of the deflection unit is prevented from coinciding with an optical axis of the first telescope.

2. The detection apparatus as claimed in claim 1, wherein the deflection unit has a deflection surface on which an incident point of the illumination beam and an optical axis of the first telescope are spaced apart from each other.

3. The detection apparatus according to claim 1 or 2, wherein the deflection unit has a deflection surface which is placed at the position of the entrance pupil of the first telescope.

4. The detection apparatus according to any one of claims 1 to 3, wherein the separation unit is a perforated mirror.

5. The detection apparatus according to any one of claims 1 to 4, further comprising an optical element configured to convert the illumination beam from the light source into a parallel beam.

6. The detection apparatus according to any one of claims 1 to 5, further comprising a second telescope, placed between the light source and the deflection unit, configured to reduce a diameter of the illumination beam from the light source, and configured to increase a diameter of the reflected beam after the reflected beam is deflected by the deflection unit.

7. The detection apparatus of any one of claims 1 to 6, further comprising:

a first imaging optical system configured to collect the reflected light beam deflected by the deflecting unit; and

a diaphragm configured to limit a diameter of the reflected light beam collected by the first imaging optical system.

8. The detection apparatus according to claim 7, further comprising a second imaging optical system configured to collect the reflected light beam passing through the diaphragm on the light receiving element.

9. The detection apparatus according to claim 8, wherein the second imaging optical system is arranged such that an optical axis of the second imaging optical system and an optical axis of the detection apparatus are prevented from coinciding with each other.

10. The detection apparatus according to any one of claims 1 to 9, wherein the light receiving element is arranged such that a center position of the light receiving surface is deviated from an optical axis of the detection apparatus.

11. The detection apparatus according to any one of claims 1 to 10, wherein the separation unit comprises an element configured to transmit and reflect the light beam.

12. The detection apparatus according to claim 11, wherein the separation unit is configured to allow the illumination light beam from the light source to travel toward the deflection unit, and is configured to reflect the reflected light beam from the deflection unit toward the light receiving element.

13. The detection apparatus according to any one of claims 1 to 12, wherein the first telescope includes a plurality of optical elements each having a refractive power, and the first telescope has no refractive power as an entire system.

14. The detection apparatus according to any one of claims 1 to 13, further comprising a control unit configured to acquire information on a distance of the object based on an output of the light receiving element.

15. An in-vehicle system, comprising:

the detection apparatus of any one of claims 1 to 14; and

a determination unit configured to determine a collision possibility between the vehicle and the object based on the information on the distance of the object acquired by the detection device.

16. The in-vehicle system according to claim 15, further comprising a control device configured to output a control signal for generating braking power in each wheel of the vehicle when it is determined that there is a possibility of collision between the vehicle and the object.

17. The in-vehicle system according to claim 15 or 16, further comprising a warning device configured to issue a warning to a driver of the vehicle when it is determined that there is a possibility of collision between the vehicle and the object.

18. A mobile device comprising a detection device according to any one of claims 1 to 14, wherein the mobile device is movable while holding the detection device.

Technical Field

The present invention relates to a detection apparatus configured to detect an object by illuminating the object and receiving reflected light reflected by the object.

Background

Light detection and ranging (LiDAR) in which the distance to an object is calculated from how long it takes to receive reflected light from the object after the object is illuminated or from the phase of the detected reflected light is known as a method of detecting an object and measuring the distance to the object.

In recent years, LiDAR has received attention as a method of measuring a distance to an object, for example, for automatic driving of automobiles.

In the automatic driving of an automobile, the automobile is required to recognize a vehicle, a person, a dangerous object, or the like as an object and take an action suitable for a distance to the recognized object, such as following or avoiding the object.

In patent document 1, a detection apparatus is disclosed in which an object is scanned with illumination light that has been emitted from a laser, passed through a separation unit, and deflected by a scanning mirror, and reflected light reflected by the object is deflected toward a light receiving unit via the scanning mirror and the separation unit to measure a position of the object and a distance to the object from the reflected light received at the light receiving unit.

CITATION LIST

Patent document

PTL 1: U.S. patent application publication No.2009/0201486

Disclosure of Invention

Technical problem

The intensity of reflected light from the object entering the detection means is lower as the object is farther away, so the detection means is required to receive as much reflected light as possible.

For this reason, it is effective to increase the light amount by arranging a telescope near the emission side of the detection device and changing the diameter of the beams of the illumination light and the reflected light. Unfortunately, this also increases the amount of unwanted light generated by reflections and scattering inside the detection arrangement.

Therefore, an object of the present invention is to provide a detection apparatus capable of suppressing reception of unnecessary light added by a telescope.

Solution to the problem

The detection device according to the present invention includes: a light source configured to emit an illumination beam; a light receiving element configured to receive a reflected light beam from an object; a deflection unit configured to deflect the illumination light beam toward the object so as to scan the object and configured to deflect the reflected light beam toward the light receiving element; a separation unit configured to allow the illumination light beam from the light source to proceed toward the deflection unit and configured to allow the reflected light beam from the deflection unit to proceed toward the light receiving element; and a first telescope configured to increase a diameter of the illumination beam deflected by the deflection unit and configured to decrease a diameter of a reflected beam from the object, wherein the deflection unit is arranged such that an optical path of a principal ray of the illumination beam at a central view angle within a scanning range of the deflection unit is prevented from coinciding with an optical axis of the first telescope.

Advantageous effects of the invention

According to the present invention, it is possible to provide a detection device capable of suppressing reception of unnecessary light by a telescope.

Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Drawings

Fig. 1 is a schematic cross-sectional view of a detection apparatus according to a first embodiment of the present invention.

Fig. 2A is a partially enlarged view of the detection apparatus according to the first embodiment.

Fig. 2B is a partially enlarged view of the detection device of the comparative example.

Fig. 3A is a diagram for illustrating the appearance of unnecessary light received in the detection apparatus of the comparative example.

Fig. 3B is a diagram for illustrating the appearance of unnecessary light received in the detection apparatus according to the first embodiment.

Fig. 3C is a diagram for illustrating the appearance of unnecessary light received in the detection apparatus according to the second embodiment of the present invention.

Fig. 3D is a diagram for illustrating the appearance of unnecessary light received in the detection apparatus according to the modified example of the second embodiment.

Fig. 4 is a partially enlarged view of the detecting device according to the second embodiment.

Fig. 5A is a partially enlarged view of the detection device of the comparative example.

Fig. 5B is a partially enlarged view of the detecting device according to the second embodiment.

Fig. 6A is a diagram for illustrating a reflected light region formed on a light receiving surface of a light receiving element in the detection apparatus of the comparative example.

Fig. 6B is a diagram for illustrating a reflected light region formed on the light receiving surface of the light receiving element in the detection apparatus according to the second embodiment.

Fig. 7 is a schematic cross-sectional view of a detecting unit according to a third embodiment of the present invention.

Fig. 8 is a schematic cross-sectional view of a detecting unit according to a fourth embodiment of the present invention.

Fig. 9 is a diagram for illustrating how reflected light from an object reenters the detection apparatus according to the fourth embodiment.

Fig. 10 is a schematic sectional view of a detecting device according to a fourth embodiment.

Fig. 11 is a schematic cross-sectional view of a detecting unit according to a fifth embodiment of the present invention.

Fig. 12A is a partially enlarged view of the detection device of the comparative example.

Fig. 12B is a partially enlarged view of a detection device of another comparative example.

Fig. 12C is a partially enlarged view of the detecting device according to the fifth embodiment.

Fig. 13 is a schematic cross-sectional view of a detecting unit according to a sixth embodiment of the present invention.

Fig. 14 is a schematic cross-sectional view of a detection apparatus according to a seventh embodiment of the present invention.

Fig. 15A is a partially enlarged view of the detection device of the comparative example.

Fig. 15B is a partially enlarged view of the detection apparatus according to the seventh embodiment.

Fig. 15C is a partially enlarged view of the detection apparatus according to the seventh embodiment.

Fig. 15D is a partially enlarged view of the detection apparatus according to the seventh embodiment.

Fig. 16 is a diagram for illustrating a reflected light region formed on a light receiving surface of a light receiving element in the detection apparatus of the comparative example.

Fig. 17 is a schematic cross-sectional view of a detecting unit according to an eighth embodiment of the present invention.

Fig. 18 is a functional block diagram of an in-vehicle system according to an embodiment.

Fig. 19 is a schematic diagram of a main portion in the vehicle of the embodiment.

Fig. 20 is a flowchart for illustrating an example of the operation of the in-vehicle system according to the embodiment.

Detailed Description

First embodiment

A detection apparatus according to a first embodiment of the present invention is described in detail below with reference to the accompanying drawings. In order to make the first embodiment easier to understand, some of the figures referred to below may be drawn on a different scale than the actual scale.

Configurations of LiDAR systems include an illumination system that illuminates an object and a receiving system that receives reflected and scattered light from the object. LiDAR systems having such a configuration are classified into a coaxial type in which the illumination system and the receiving system are oriented in exactly the same direction and a non-coaxial type in which the illumination system and the receiving system are configured separately from each other.

The detection apparatus according to the first embodiment is suitable for a LiDAR system of a coaxial type, and the optical axis of the illumination system and the optical axis of the receiving system coincide in a perforated mirror.

In the automatic driving in which it is assumed that the automobile is driven at a high speed, it is required to detect a farther object and measure a distance to the object (i.e., ranging).

As the object is farther away, the reflected or scattered light returning from the object to the detection device is weaker. For example, the amount of reflected light from an object 50m away entering the detection device is about two digits smaller than the amount of reflected light from an object 5m away entering the detection device.

Thus, one way to receive as much reflected light as possible from a distant object is to increase the amount of illumination light exiting the detection device by, for example, increasing the power of the illumination light source. However, since safety to the human eye is required to be considered, when the object is a human, the power of the illumination light source can be increased only to a limited level. Therefore, it is required to design a way of receiving as much reflected light as possible from a distant object without increasing the amount of illumination light.

As the distance to the object increases, the difficulty of measuring the size of the object also increases.

In particular, in high-speed driving, it is required to detect the size of a distant object at an early timing and use the detected size as a basis for determining the next course of action, and the detection accuracy of the size of the distant object is also important accordingly.

The reflected light and the scattered light generated inside the detection device are unnecessary light which reduces the accuracy of measurement, and it is preferable that the light receiving unit receives as little unnecessary light as possible.

When unnecessary light is generated in large amounts and received together with reflected light received from the object, the detection performance of the detection device decreases, and the error of the calculated measured amount increases. Further, when the light receiving unit receives a large amount of unnecessary light generated when the illumination light is emitted from the detection device, the resetting of the electric charge in the light receiving element cannot be completed before the reflected light from the object is received, with the result that the reflected light from the object cannot be distinguished from the unnecessary light. Therefore, detection and ranging of an object cannot be performed.

Patent document 1 does not investigate a configuration for suppressing reception of unnecessary light generated inside the detection apparatus.

Fig. 1 is a schematic cross-sectional view of a detection apparatus 1 according to a first embodiment. In fig. 1, the light path for illumination and the light path for light reception are illustrated separately.

The detection apparatus 1 according to the first embodiment includes a light source forming unit (light source unit) 10, a received illumination light separating unit (separating unit) 20, a driven mirror (deflecting unit) 30, a telescope (first telescope) 40, a light receiving unit 50, and a control unit 100.

The light source forming unit 10 includes a light source 11 and a collimator 12. A divergent light beam (illumination light beam) emitted from the light source 11 is converted into a parallel light beam having a beam diameter r1a by the collimator 12. The definition of parallel light beam here includes not only a strictly parallel light beam but also a substantially parallel light beam such as a weakly divergent light beam and a weakly convergent light beam.

The reception illumination light separation unit 20 is constituted by, for example, a perforated mirror or a beam splitter, and has a function of separating an illumination light path from a reception light path. Specifically, the received illumination light separation unit 20 allows the illumination light beam from the light source forming unit 10 to proceed to the driven mirror 30, while allowing the light beam from the driven mirror 30 to proceed to the light receiving unit 50. Here, the perforated mirror is a mirror (reflecting member) having an opening portion. The light beam incident on the perforated mirror is separated into a light beam passing through the opening portion (air) and a light beam reflected by the mirror surface (reflection surface). The opening portion of the perforated mirror may not be a hollow hole, and a transmission member may be provided in the opening portion.

The driven mirror 30 has an effective diameter r1 a' and is a two-axis driven mirror to be rotated about the Y axis in fig. 1 or an axis perpendicular to the Y axis. The beam diameter r1a of the illumination beam is less than the effective diameter r1 a' of the driven mirror 30.

The telescope 40 is an optical system that includes a plurality of optical elements (lenses) having refractive power (refractive power) and has no refractive power as the entire system. The telescope 40 is placed on the illumination side of the driven mirror 30, and the driven mirror 30 is positioned at the optical entrance pupil position of the telescope 40. From the driven mirror 30 side to the exit pupil, the optical magnification β of the telescope 40 is larger than 1(| β | >1), and the diameter of the entrance pupil where the driven mirror 30 is located is larger than the effective diameter r1 a' of the driven mirror 30.

The light receiving unit 50 includes a light collecting optical system (first imaging optical system) 51 and a light receiving element 52. The reflected light beam from the illuminated object is collected by the light collection optical system 51 and received by the light receiving element 52.

The control unit 100 controls the light source 11 provided in the light source forming unit 10, the driven mirror 30, and the light receiving element 52 provided in the light receiving unit 50. The control unit 100 drives the light source 11 and the driven mirror 30 at respective predetermined driving voltages and driving frequencies of the light source 11 and the driven mirror 30, and measures a waveform of received light received at the light receiving element 52 using a specific frequency.

The parallel light beam which has been emitted from the light source forming unit 10 and has the beam diameter r1a passes through the received illumination light separating unit 20, is deflected by the driven mirror 30, and becomes an illumination light beam having the beam diameter r1b on the emission surface via the telescope 40 to illuminate an object outside the detection apparatus 1.

The light beam, which comprises the reflected light beam reflected by the illuminated object and has an effective diameter (i.e., the effective emitting diameter of the telescope 40) r1 b', is then re-entered from the emitting surface of the telescope 40. The re-entered beam travels through the telescope 40 and is deflected by the driven mirror 30 to become a beam having a beam diameter r1 a'. The deflected light beams are deflected in a direction different from the direction of the illumination light beams in the reception illumination light separation unit 20 to be received by the light reception unit 50.

The control unit 100 measures the difference between the light reception time acquired in the light receiving element 52 and the light emission time of the light source 11, or the difference between the phase of the received light signal acquired in the light receiving element 52 and the phase of the output signal from the light source 11. The difference is multiplied by the speed of light to determine the distance to the object.

Although the reception illumination light separation unit 20 in the detection apparatus 1 according to the first embodiment allows the light beam from the light source forming unit 10 to travel toward the driven mirror 30 and deflects the light beam from the driven mirror 30 toward the light reception unit 50, the reception illumination light separation unit 20 is not limited thereto. The received illumination light separation unit 20 may allow the light beam from the driven mirror 30 to travel toward the light receiving unit 50 while deflecting the light beam from the light source forming unit 10 toward the driven mirror 30.

As shown in fig. 1, in the detection apparatus 1 according to the first embodiment, the driven mirror 30 is driven at high speed, and therefore, in view of weight, the driven mirror 30 is required to have a small diameter, with the result that the effective diameter of the light beam deflected by the driven mirror 30 is naturally small. Thus, the driven mirror 30 easily limits the effective diameter of the light beam including the reflected light beam from the illuminated object.

By using the effective diameter r1a 'of the driven mirror 30 and the optical magnification β of the telescope 40, the effective diameter r1 b' of the light beam re-entering from the emission surface of the telescope 40 is expressed by the following expression (1).

[ mathematical expression 1]

r1b′＝r1a′×|β|···(1)

As shown in fig. 1, the effective diameter r1b 'of the light beam is | β | (>1) times the effective diameter r1 a' of the driven mirror 30. Thus, the detection apparatus 1 according to the first embodiment can receive more reflected and scattered light beams from the object than when the telescope 40 is not provided.

By using the deflection angle θ 1 of the principal ray of the parallel light beam deflected by the driven mirror 30 and the optical magnification β of the telescope 40, the deflection angle θ 2 of the principal ray of the illumination light beam emitted from the telescope 40 is expressed by the following expression (2).

[ mathematical expression 2]

As shown in fig. 1, since the optical magnification β of the telescope 40 is larger than 1, the deflection angle θ 2 of the principal ray of the illumination light beam is smaller than the deflection angle θ 1 of the principal ray of the parallel light beam deflected by the driven mirror 30.

Therefore, in the detection apparatus 1 according to the first embodiment, the angle of view is narrow, but the detection interval is also narrow, with the result that the detection resolution can be improved.

In the detection apparatus 1 according to the first embodiment, the optical path of the principal ray in the illumination light beam deflected by the driven mirror 30, that is, the optical path observed when the driven mirror 30 is driven, is illustrated in a Y-Z cross section in fig. 2A.

Fig. 2A is a partially enlarged view of the detecting device 1 according to the first embodiment. In fig. 2A, a principal ray Sa included in the illumination light beam and traveling in an outermost optical path (maximum angle of view within the range of scanning angles of view) outside the optical axis of the telescope 40, a principal ray Sb included in the illumination light beam and traveling in an optical path of a central angle of view within the range (range of scanning angles of view) in which the driven mirror 30 can be driven, and a principal ray Sc included in the illumination light beam and traveling in an optical path closest to the optical axis of the telescope 40 are also illustrated.

Fig. 2B is a partially enlarged view of the detection apparatus 1, in which the driven mirror 30 is arranged such that the optical path of the central angle of view (illumination optical path) coincides with the optical axis Ax of the telescope 40.

As shown in fig. 2B, when the driven mirror 30 in the detection apparatus 1 is arranged such that the optical path of the principal ray Sb of the illumination light beam at the central angle of view within the range of the scanning angle of view of the driven mirror 30 coincides with the optical axis Ax of the telescope 40, the reflected light beams RF1 and RF2, which are light beams returned from the optical elements provided in the telescope 40, travel so as to overlap with the illumination light beam along the optical axis Ax and enter the light receiving unit 50. In addition, also in the vicinity of the optical path of the illumination light beam shown in fig. 2B, the reflected and scattered light beam from the optical element provided in the telescope 40 returns more or less back and enters the light receiving unit 50. Therefore, when the optical axis Ax of the telescope 40 coincides with the optical path from the center angle of view of the driven mirror 30 as shown in fig. 2B, the above-described unnecessary light, such as the reflected light beams RF1 and RF2, is thereby generated within a given angle of view as shown in fig. 3A.

Fig. 3A and 3B are diagrams for illustrating the appearance of unnecessary light received on the light receiving surface 52D of the light receiving element 52 when the driven mirror 30 is driven two-dimensionally in the detection apparatus 1. An intersection point at which two dotted axes are orthogonal to each other in the drawing represents a driving center viewing angle of the driven mirror 30, a horizontal axis represents a viewing angle observed when the driven mirror 30 is driven in the direction X, and a vertical axis represents a viewing angle observed when the driven mirror 30 is driven in the direction Y.

In fig. 3A and 3B, a white portion indicates a viewing angle at which unnecessary light is generated, and a black portion indicates a viewing angle at which unnecessary light is not generated.

On the other hand, as shown in fig. 2A, when the driven mirror 30 in the detection apparatus 1 according to the first embodiment is arranged such that the optical path (illumination optical path) of the principal ray Sb of the illumination light beam at the central angle of view within the range of the scanning angle of view of the driven mirror 30 does not coincide with the optical axis Ax of the telescope 40, the illumination light beam does not travel along the optical axis Ax of the telescope 40.

Therefore, the optical element in the telescope 40 provided in the detection apparatus 1 according to the first embodiment generates unnecessary light that is recognizable only in the viewing angle range away from the center of the light receiving surface 52D of the light receiving element 52, as shown in fig. 3B.

As described above, according to the detection apparatus 1 of the first embodiment, by placing the driven mirror 30 at the position of the entrance pupil of the telescope 40 having the optical magnification β larger than 1, most of the reflected and scattered light beams from the illuminated object can be taken, and the detection interval can be made close. Therefore, the detection resolution is improved.

In the detection apparatus 1, the scanning angle of the driven mirror 30 is set so that the optical path of the principal ray of the illumination beam at the central viewing angle within the range of the scanning viewing angle of the driven mirror 30 does not coincide with the optical axis Ax of the telescope 40 (to prevent the driven mirror 30 from deflecting the illumination beam in a direction extending along the optical axis of the telescope 40 at the central viewing angle within the range of the scanning viewing angle of the driven mirror 30). Specifically, the scanning angle of the driven mirror 30 is set so that the principal ray of the illumination light beam obliquely enters the object (illuminated surface) in one cross section including the optical axis. With this configuration, it is possible to suppress reception of unnecessary light at and around the central viewing angle.

In other words, by arranging the driven mirror 30 such that the central angle of view of the driven mirror 30 is an angle of view outside the optical axis of the telescope 40, it is possible to suppress reception of unnecessary light.

This gives the detection apparatus 1 improved ranging performance with respect to distant objects and improved detection resolution with respect to the size of distant objects.

Second embodiment

Fig. 4 is a partially enlarged view of the detecting unit 2 according to the second embodiment of the present invention. In fig. 4, a principal ray Sa included in the illumination light beam and traveling in the outermost optical path (maximum angle of view within the range of scanning angles of view) outside the optical axis of the telescope 40, a principal ray Sb included in the illumination light beam and traveling in the optical path of the center angle of view within the range (range of scanning angles of view) in which the driven mirror 30 can be driven, and a principal ray Sc included in the illumination light beam and traveling in the optical path closest to the optical axis of the telescope 40 are also illustrated.

The detection apparatus 2 according to the second embodiment has a configuration similar to that of the detection apparatus 1 according to the first embodiment, and the same members in the detection apparatus 2 as those in the detection apparatus 1 are denoted by the same reference numerals so that the description of the members is omitted.

In the detection apparatus 2 according to the second embodiment, the telescope 40 is arranged to be eccentric. Specifically, as shown in fig. 4, when an intersection point between the optical axis Ax of the telescope 40 and the driven mirror 30 is set to AXP and an incident point on a mirror surface (deflection surface, scanning surface) of the driven mirror 30 at which an illumination beam enters is set to ILP, the telescope 40 is decentered so that AXP and ILP do not coincide.

In other words, the telescope 40 is arranged such that the optical axis Ax of the telescope 40 does not intersect the incidence point ILP of the illumination beam on the mirror surface of the driven mirror 30. That is, the optical path of the principal ray of the illumination beam at the central view angle within the range of the scanning view angle of the driven mirror 30 does not coincide with the optical axis Ax of the telescope 40.

Fig. 5A is a partially enlarged view of the detection apparatus of a comparative example in which the driven mirror 30 is arranged such that the optical path of the principal ray of the illumination light beam at the central angle of view within the range of the scanning angle of view of the driven mirror 30 coincides with the optical axis Ax of the telescope 40. Fig. 5B is a partially enlarged view of the detection apparatus 2 according to the second embodiment in which the driven mirror 30 is arranged such that the optical path of the principal ray of the illumination beam at the central angle of view within the range of the scanning angle of view of the driven mirror 30 does not coincide with the optical axis Ax of the telescope 40.

Fig. 6A is a diagram for illustrating a positional relationship between the light receiving surface 52D of the light receiving element 52 and the reflected light regions RF1G and RF2G observed in the case of fig. 5A, the reflected light regions RF1G and RF2G being formed in a section parallel to the light receiving surface 52D by the reflected light beams RF1 and RF2 from the telescope 40. Fig. 6B is a diagram for illustrating a positional relationship between the light receiving surface 52D of the light receiving element 52 and the reflected light regions RF1G and RF2G observed in the case of fig. 5B, the reflected light regions RF1G and RF2G being formed in a section parallel to the light receiving surface 52D by the reflected light beams RF1 and RF2 from the telescope 40.

As shown in fig. 5A, when the optical path of the principal ray Sb of the illumination light beam at the central view angle within the range of the scanning view angle of the driven mirror 30 coincides with the optical axis Ax of the telescope 40, the reflected light beams RF1 and RF2 from the optical elements provided in the telescope 40 are each reflected in the same direction as the reflection direction of the other reflected light along the optical axis Ax.

This makes the reflected light beams RF1 and RF2 arriving from the telescope 40 blur on the light receiving surface of the light receiving element 52 of the light receiving unit 50.

The reflected light regions RF1G and RF2G are formed so as to overlap with the light receiving surface 52D in a section parallel to the light receiving surface 52D as shown in fig. 6A when the optical path of the principal ray Sb of the illumination light beam at the central angle of view within the range of the scanning angle of view of the driven mirror 30 coincides with the optical axis Ax of the telescope 40 as described above.

On the other hand, as shown in fig. 5B, when the optical path of the principal ray Sb of the illumination light beam at the central viewing angle within the range of the scanning viewing angle of the driven mirror 30 does not coincide with the optical axis Ax of the telescope 40, the reflection angles of the reflected light beams RF1 and RF2 from the optical elements provided in the telescope 40 are dispersed.

As shown in fig. 6B, this spaces the reflected light regions RF1G and RF2G from the light receiving surface 52D.

Therefore, as shown in fig. 3C, the viewing angle range of unnecessary light received on the light receiving surface 52D of the light receiving element 52 from the optical element provided in the telescope 40 can be made narrower than in fig. 3A.

When the optical element provided in the telescope 40 has a reflection surface that significantly contributes to the generation of unnecessary light, intense unnecessary light is generated at a viewing angle that depends on the direction of the reflected light beam from the reflection surface. In other words, the angle of view at which intense unnecessary light is generated varies depending on the direction in which the telescope 40 is decentered. Thus, by setting the angle of the driven mirror 30 so that the optical path of the principal ray Sb of the illumination light beam at the central viewing angle within the range of the scanning viewing angle of the driven mirror 30 does not coincide with the optical axis Ax of the telescope 40 as in the detection apparatus 1 according to the first embodiment in addition to decentering the telescope 40, the viewing angle range of the unnecessary light can be narrowed and can be moved to a point away from the center of the light receiving surface 52D of the light receiving element 52, as shown in fig. 3D.

Although unnecessary light is allowed to remain in fig. 3D for the sake of description, it is preferable to set the angle of the driven mirror 30 and the eccentric position of the telescope 40 so that the unnecessary light is completely removed from the light receiving surface 52D of the light receiving element 52.

As shown in fig. 6B, when the amounts of intervals of the reflected light regions RF1G and RF2G from the light receiving surface 52D are set to RF1s and RF2s, respectively, the amounts of intervals and the directions of intervals depend on the arrangement of optical elements provided in the telescope 40 and on the decentering direction of the telescope 40. Therefore, it is preferable to consider the angle of view at which unnecessary light is generated and the angle of view at which the detection device 2 is used when determining the direction in which the telescope 40 is decentered.

As described above, according to the detection apparatus 2 of the second embodiment, it is possible to suppress generation of unnecessary light in the apparatus over a wider viewing angle range than in the detection apparatus 1 according to the first embodiment while taking a large part of the reflected and scattered light beam from the distant object illuminated by the apparatus.

In-vehicle LiDAR systems are generally required to be wider at viewing angles that are horizontal to ground than at viewing angles that are perpendicular to ground. Therefore, in the detection apparatus 2 according to the second embodiment, it is preferable to set the direction X to a viewing angle horizontal to the ground, set the direction Y to a viewing angle vertical to the ground, and decenter the telescope in the direction Y.

Third embodiment

Fig. 7 is a schematic cross-sectional view of a detecting unit 3 according to a third embodiment of the present invention. In fig. 7, the light path for illumination and the light path for light reception are illustrated separately.

The detection apparatus 3 according to the third embodiment has a configuration similar to that of the detection apparatus 1 according to the first embodiment except that a variable power optical system 60 is provided, and the same members in the detection apparatus 3 as those in the detection apparatus 1 are denoted by the same reference numerals so that the description of the members is omitted.

A variable power optical system (second telescope) 60 is placed between the light source forming unit 10 and the driven mirror 30. The variable power optical system 60 in the third embodiment has an optical magnification β (| β | <1), and converts the parallel light beam having passed through the perforated mirror 20 and having the light beam diameter r3a into a parallel light beam having a light beam diameter r3b smaller than r3 a. Specifically, by using the effective diameter r3a and the optical magnification β of the variable power optical system 60, the light beam diameter r3b is expressed by the following expression (3).

[ mathematical expression 3]

r3b＝r3a×|β|···(3)

The beam diameter r3b of the illumination beam having passed through the variable power optical system 60 is smaller than the effective diameter of the driven mirror 30.

The parallel light beam having been emitted from the light source forming unit 10 and having the beam diameter r3a passes through (is transmitted through) the perforated mirror 20, and is converted into an illumination light beam having the beam diameter r3b by the variable power optical system 60. The illumination beam is deflected by the driven mirror 30 and becomes an illumination beam having a beam diameter r3c on the emission surface via the telescope 40 to illuminate an object outside the detection apparatus 3. The light beam, which comprises the reflected light beam reflected by the illuminated object and has an effective diameter (i.e., the effective emitting diameter of the telescope 40) r3 c', is then re-entered from the emitting surface of the telescope 40. The re-entered beam travels through the telescope 40 and is deflected by the driven mirror 30 to become a beam having a beam diameter r3 b'. The deflected light beam is converted by the variable power optical system 60 into a received light beam having a beam diameter r3a 'greater than r3 b'. Then, the reception light beam is deflected (reflected) in a direction different from the direction of the illumination light beam at the perforated mirror 20 to be received by the light receiving unit 50.

Then, the control unit 100 measures the difference between the light receiving time acquired in the light receiving element 52 and the light emitting time of the light source 11, or the difference between the phase of the received light signal acquired in the light receiving element 52 and the phase of the output signal from the light source 11. The difference is multiplied by the speed of light to determine the distance to the object.

As shown in fig. 7, in the detection apparatus 3 according to the third embodiment, the driven mirror 30 is driven at high speed, and therefore, in view of weight, the driven mirror 30 is required to have a small diameter, with the result that the effective diameter of the light beam deflected by the driven mirror 30 is naturally small. Thus, the driven mirror 30 easily limits the effective diameter of the light beam including the reflected light beam from the illuminated object.

Thus, the effective diameter r3 b' of the light beam can be considered to be equal to the effective diameter of the driven mirror 30.

The beam diameter r3a 'of the received light received by the receiving unit 50 is expressed by the following expression (4) by using the effective diameter r3 b' of the light beam and the optical magnification β of the variable power optical system 60.

[ mathematical expression 4]

When the diameter of the opening formed in the perforated mirror 20 is set to H, the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio R at which a part of the received light beam is lost due to the perforated mirror 20) is expressed by the following expression (5).

[ mathematical expression 5]

When the variable power optical system 60 is not provided, the beam diameter r3a 'of the received light beam received by the light receiving unit 50 is equal to the effective diameter of the driven mirror 30, that is, the effective diameter r3 b' of the light beam.

When the beam diameter of the parallel light beam emitted from the light source forming unit 10 is r3a and the beam diameter of the parallel light beam having passed through the perforated mirror 20 and entered the driven mirror 30 is r3b, r3a is equal to r3 b.

In this case, the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio R' at which a part of the received light beam is lost due to the perforated mirror 20) is expressed by the following expression (6).

[ mathematical expression 6]

Therefore, according to expression (5) and expression (6), the ratio of the loss ratio R to R' is expressed by the following expression (7).

[ mathematical expression 7]

Therefore, including the variable power optical system 60 enables the detection apparatus 3 according to the third embodiment to reduce β the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio of the received light due to the perforated mirror 20)²And (4) doubling.

By using the effective diameter r3b 'of the driven mirror 30 and the optical magnification β' (| β '| >1) of the telescope 40, the effective diameter r3 c' of the light beam re-entering from the emission surface of the telescope 40 is expressed by the following expression (8).

[ mathematical expression 8]

r3c′＝r3b′×|β′|···(8)

As shown in fig. 7, the effective diameter r3c ' of the light beam is | β ' | (>1) times the effective diameter r3b ' of the driven mirror 30.

The received-light amount F' of the light receiving unit 50 in the detection apparatus 3 according to the third embodiment is compared with the received-light amount F of the light receiving unit 50 in the detection apparatus 3 as a comparative example in which any one of the variable power optical system 60 and the telescope 40 is not included.

When the light quantity of the light beam having the effective diameter r3 b' is 1 at the time of reentering the driven mirror 30, the received-light quantity F of the light receiving unit 50 in the detection apparatus 3 as a comparative example is obtained from expression (6) by expression (9) below.

[ mathematical expression 9]

When the light quantity of the light beam having the effective diameter r3b 'is similarly 1 upon reentering the driven mirror 30, the received-light quantity F' of the light receiving unit 50 in the detection apparatus 3 according to the third embodiment is obtained from expression (5) and expression (8) through the following expression (10).

[ mathematical expression 10]

When r3b ', β, and β ' are set to 2H, 0.2, and 3, respectively, the received-light amount ratio F '/F is expressed by the following expression (11).

[ mathematical expression 11]

Therefore, the detection apparatus 3 according to the third embodiment can receive light at the light receiving unit 50 with a light amount that is about twelve times the received light amount in the detection apparatus 3 as a comparative example.

By using the deflection angle θ 1 of the principal ray of the parallel light beam deflected by the driven mirror 30 and the optical magnification β' of the telescope 40, the deflection angle θ 2 of the principal ray of the illumination light beam emitted from the telescope 40 is expressed by the following expression (12).

[ mathematical expression 12]

As shown in fig. 7, since the optical magnification β' of the telescope 40 is larger than 1, the deflection angle θ 2 of the principal ray of the illumination light beam is smaller than the deflection angle θ 1 of the principal ray of the parallel light beam deflected by the driven mirror 30.

Therefore, in the detection apparatus 3 according to the third embodiment, the angle of view is narrow, but the detection interval is also narrow, with the result that the detection resolution can be improved.

In the detection of reflected light from a distant object, the detection device becomes more difficult to detect the size of the object as the distance between the detection device and the object becomes longer.

In particular, in automatic driving in which it is assumed that the automobile is driven at a high speed, it is required to detect the size of a distant object at an early timing and use the detected size as a basis for determining the next course of action, and the detection accuracy of the size of the distant object is also important accordingly.

The detection apparatus 3 according to the third embodiment has a new effect in that not only the improvement of the received-light amount but also the improvement of the detection resolution is achieved.

In the detection apparatus 3 according to the third embodiment, the variable power optical system 60 placed between the perforated mirror 20 and the driven mirror 30 may include a perforated mirror. In that case, it is required to modify the focal length of the light collection optical system 51 of the light receiving unit 50, but the above concept is applied to the opening and the light receiving efficiency as it is.

In the detection apparatus 3 according to the third embodiment, the collimator 12 converts the divergent light beam emitted from the light source 11 in the light source forming unit 10 into a parallel light beam having a light beam diameter r3a smaller than the opening diameter H of the perforated mirror 20. However, the detection device 3 is not limited thereto, and a diaphragm may be provided between the light source forming unit 10 and the perforated mirror 20.

In the detection apparatus 3 according to the third embodiment, the light source forming unit 10 constituted only by the light source 11 and the collimator 12 is not limited thereto. When the angle of divergence from the light source 11 is asymmetric, a cylindrical lens or the like may be provided in the light source forming unit 10 to shape the divergent light beam emitted from the light source 11 and then adjust the beam diameter with the provided diaphragm.

Here, it is important to keep the light quantity of the illumination light beam from the detection device at or below the upper limit determined in consideration of safety to the human eye, and the effective diameter of the illumination light beam can be determined in the light source forming unit 10 by using the diaphragm.

Fourth embodiment

Fig. 8 is a schematic cross-sectional view of a detecting unit 4 according to a fourth embodiment of the present invention. In fig. 8, the light path for illumination and the light path for light reception are illustrated separately.

The detection apparatus 4 according to the fourth embodiment has a configuration similar to that of the detection apparatus 1 according to the first embodiment except that a field stop 55 is newly provided in the light receiving unit 50, and the same members in the detection apparatus 4 as those in the detection apparatus 1 are denoted by the same reference numerals so that the description of the members is omitted.

The light receiving unit 50 includes a light collecting optical system 51, a light receiving element 52, and a field stop (diaphragm) 55. A field stop 55 is provided at the light collection point of the light collection optical system 51 to limit the beam diameter of the light beam collected by the light collection optical system 51.

A light beam including a reflected light beam from an illuminated object is collected by the light collection optical system 51, passes through an aperture in the field stop 55, and is received by the light receiving element 52.

The parallel light beam having the beam diameter r4a and having been emitted from the light source forming unit 10 passes through the received illumination light separating unit 20, is deflected by the driven mirror 30, and becomes an illumination light beam having the beam diameter r4b on the emission surface via the telescope 40 to illuminate an object outside the detection apparatus 4.

The light beam, which comprises the reflected light beam reflected by the illuminated object and has an effective diameter (i.e., the effective emitting diameter of the telescope 40) r4 b', is then re-entered from the emitting surface of the telescope 40. The re-entered beam travels through the telescope 40 and is deflected by the driven mirror 30 to become a beam having a beam diameter r4 a'. The deflected light beams are deflected in a direction different from the direction of the illumination light beams in the reception illumination light separation unit 20 to be received by the light reception unit 50.

The control unit 100 measures the difference between the light reception time acquired in the light receiving element 52 and the light emission time of the light source 11, or the difference between the phase of the received light signal acquired in the light receiving element 52 and the phase of the output signal from the light source 11. The difference is multiplied by the speed of light to determine the distance to the object.

As shown in fig. 8, in the detection apparatus 4 according to the fourth embodiment, the driven mirror 30 is driven at high speed, and therefore, in view of weight, the driven mirror 30 is required to have a small diameter, with the result that the effective diameter of the light beam deflected by the driven mirror 30 is naturally small. Thus, the driven mirror 30 easily limits the effective diameter of the light beam including the reflected light beam from the illuminated object.

By using the effective diameter r4a 'of the driven mirror 30 and the optical magnification β (| β | >1) of the telescope 40, the effective diameter r4 b' of the light beam re-entering from the emission surface of the telescope 40 is expressed by the following expression (13).

[ mathematical expression 13]

r4b′＝r4a′×|β|···(13)

As shown in fig. 8, the effective diameter r4b 'of the light beam is | β | (>1) times the effective diameter r4 a' of the driven mirror 30. Thus, the detection apparatus 4 according to the fourth embodiment can receive more reflected and scattered light beams from the object than when the telescope 40 is not provided.

By using the deflection angle θ 1 of the principal ray of the parallel light beam deflected by the driven mirror 30 and the optical magnification β of the telescope 40, the deflection angle θ 2 of the principal ray of the illumination light beam emitted from the telescope 40 is expressed by the following expression (14).

[ mathematical expression 14]

As shown in fig. 8, since the optical magnification β of the telescope 40 is larger than 1, the deflection angle θ 2 of the principal ray of the illumination light beam is smaller than the deflection angle θ 1 of the principal ray of the parallel light beam deflected by the driven mirror 30.

Therefore, in the detection apparatus 4 according to the fourth embodiment, the angle of view is narrow, but the detection interval is also narrow, with the result that the detection resolution can be improved.

Fig. 9 is a diagram for illustrating how a light beam from the object 200 reenters the detection apparatus 4 according to the fourth embodiment.

The distance from the detection device 4 to the object 200 is set to p, where the area of the object 200 to be illuminated is set toAnd the maximum angle of view of the light beam received on the emission surface of the telescope 40 is set to θ_STC。

Maximum angle of view theta of the light beam when received on the emitting surface of the telescope 40_STCThe light receiving element 52 also receives unnecessary light, such as light beams from outside the viewing angle and scattered light beams generated outside the viewing angle and inside the apparatus, when the viewing angle of the object 200 to be illuminated is larger.

Therefore, it is preferable to configure the detection apparatus 4 according to the fourth embodiment so that the following expression (15) is satisfied.

[ mathematical expression 15]

Fig. 10 is a diagram for illustrating how a light beam from an object 200 is received by the light receiving element 52 in the detection apparatus 4 according to the fourth embodiment, and a principal ray is illustrated in fig. 10.

As shown in fig. 10, the angle at which the light beam from the object 200 enters the surface of the driven mirror 30 when the driven mirror 30 is stationary is set to θ_SMCAt the same time, the angle θ is adjusted by using the optical magnification β of the telescope 40_SMCExpressed by the following expression (16).

[ mathematical expression 16]

θ_SMC＝θ_STC×|β|···(16)

Thus, when the focal length of the light collection optical system 51 is set to fc, the image height y of the light beam collected on the light receiving surface 52D of the light receiving element 52 when the driven mirror 30 is stationary from the maximum angle of view_RExpressed by the following expression (17).

[ mathematical expression 17]

y_R＝fc×tanθ_SMC···(17)

Thus, in order to efficiently receive the light beam from the object 200, i.e., in order to avoid receiving unnecessary light, it is preferable to set the effective light receiving diameter D of the light receiving element 52 so as to satisfy the following expression (18).

[ mathematical expression 18]

D≤2×y_R···(18)

In practice, adjustment of the focal length fc of the light collection optical system 51 is more often selected for the purpose of versatility rather than the limitation of the effective light receiving diameter D of the light receiving element, and there is a case where the effective light receiving diameter D cannot be designed to satisfy expression (18).

In this case, by providing the field stop 55 at the light collection point of the light collection optical system 51, the light reception angle of view of the light receiving element 52 can be limited to a desired angle of view.

When the aperture diameter of the field stop 55 is set to P_stDiameter P of hole_stIs designed to satisfy the following expression (19).

[ mathematical expression 19]

P_st≤2×y_R···(19)

By setting the field stop 55 in this way, even when the effective light receiving diameter D cannot be designed to satisfy expression (18), it is possible to receive only the light beam from a desired angle of view. Therefore, it is possible to suppress reception of unnecessary light such as light beams from other viewing angles and reflected or scattered light beams inside the apparatus.

In the fourth embodiment, expression (19) is set as the hole diameter P for the field stop 55 having a single light beam_stThe conditions of (1). However, in practice, the spot diameter at the light collection point is also required to be considered, and for the purpose of receiving a large amount of light, may be the hole diameter P of the field stop 55_stA range slightly wider than expression (19) is set.

It is desirable that about half of the received light beam at the viewing angle is blocked by the aperture stop and the amount of received light outside the optical axis is halved accordingly. However, when the spot diameter at the hole portion is large, the amount of received light outside the optical axis slowly decreases and most of the received light beams outside the angle of view are also received, with the result that the S/N ratio is poor with respect to the amount of received light inside the optical axis. Thus, the size of the object is incorrectly determined.

Thus, it is important to suppress reception of unnecessary light while acquiring most of the reflected light beam in a manner of balancing acquisition of most of the reflected light beam with suppression of reception of unnecessary light. Thus, the aperture diameter P of the field stop 55_stIs determined such that taking a balance between the majority of the reflected light beam and suppressing reception of unnecessary light results in the greatest improvement in the quality of the received light signal.

Although the illumination area, the light receiving angle of view, and the like are regarded as circular in the description given above, the aperture of the field stop 55 may have a rectangular or elliptical shape depending on the illumination shape, the light receiving angle of view to be detected, or other factors.

According to the detection device 4 of the fourth embodiment, therefore, it is possible to appropriately block unnecessary light while acquiring most of the reflected light beams from the object, and as a result, it is possible to measure the distance of the object from a longer distance with improved distance measurement accuracy. Since the angle of view is limited, the detection resolution in the detection of the size of the object can also be improved.

Fifth embodiment

Fig. 11 is a schematic cross-sectional view of a detecting unit 5 according to a fifth embodiment of the present invention. Also illustrated in fig. 11 is a light path for light reception.

The detection apparatus 5 according to the fifth embodiment has a configuration similar to that of the detection apparatus 4 according to the fourth embodiment except that a re-imaging optical system 56 is newly provided in the light receiving unit 50, and the same members in the detection apparatus 5 as those in the detection apparatus 4 are denoted by the same reference numerals so that the description of the members is omitted.

The light receiving unit 50 includes a light collecting optical system 51, a light receiving element 52, a field stop 55, and a re-imaging optical system (second imaging optical system) 56. The re-imaging optical system 56 is provided between the field stop 55 and the light receiving element 52 so as to place the field stop 55 and the light receiving surface 52D of the light receiving element 52 in a substantially conjugate relationship with each other. The re-imaging optical system 56 collects the light beam having passed through the field stop 55 onto the light receiving surface 52D of the light receiving element 52.

The beam including the reflected beam reflected from the object illuminated by the detection apparatus 5 according to the fifth embodiment re-enters from the emission surface of the telescope 40. The re-entered beam travels through the telescope 40 and is deflected by the driven mirror 30 to become a beam having a beam diameter r5 a'. The deflected light beams are deflected by the reception illumination light separation unit 20 in a direction different from the direction of the illumination light beams to be received by the light reception unit 50.

The control unit 100 measures the difference between the light reception time acquired in the light receiving element 52 and the light emission time of the light source 11, or the difference between the phase of the received light signal acquired in the light receiving element 52 and the phase of the output signal from the light source 11. The difference is multiplied by the speed of light to determine the distance to the object.

In the detection apparatus 5, the light receiving surface 52D of the light receiving element 52 and the field stop 55 are desirably arranged adjacent to each other.

However, when the light receiving surface 52D is inside the light receiving element 52, the numerical aperture NA of the light collection optical system 51 is too large in terms of the holding performance, and therefore there are cases in which not all of the collected light beams can be received by the light receiving element 52.

Fig. 12A and 12B are each a partially enlarged view of the detection device 5 as a comparative example. Fig. 12C is a partially enlarged view of the detecting device 5 according to the fifth embodiment.

In fig. 12A, the light receiving surface 52D is closer to the inside than a holding unit (not shown) such as the light receiving element 52, and the collected light beam having passed through the field stop 55 is spread on the light receiving surface 52D behind the field stop 55 to be wider than the surface area of the light receiving surface 52D. Therefore, the light illustrated as the hatched portion is not received.

As understood from expression (17) and expression (19), this can be achieved by extending the focal length f of the light collection optical system 51_cTo prevent it. However, in that case, as shown in fig. 12B, the optical path behind the light collection optical system 51 is extended, and the size of the apparatus increases.

As shown in fig. 12C, the detection apparatus 5 according to the fifth embodiment solves this problem by providing a re-imaging optical system 56 between the field stop 55 and the light receiving element 52. This forms an image of the field stop 55 on the light receiving surface 52D of the light receiving element 52, and thus can prevent loss of light in a hatched portion representing light that cannot be received.

As described above, according to the detection apparatus 5 of the fifth embodiment, by providing the re-imaging optical system 56 between the field stop 55 and the light receiving element 52, the reflected light beam can be efficiently received irrespective of the position of the light receiving surface 52D of the light receiving element 52, and an increase in the size of the apparatus can also be prevented.

Sixth embodiment

Fig. 13 is a schematic cross-sectional view of a detecting unit 6 according to a sixth embodiment of the present invention. In fig. 13, the optical path for illumination and the optical path for light reception are illustrated separately.

The detection apparatus 6 according to the sixth embodiment has a configuration similar to that of the detection apparatus 5 according to the fifth embodiment except that a variable power optical system 60 is newly provided, and the same members in the detection apparatus 6 as those in the detection apparatus 5 are denoted by the same reference numerals so that the description of the members is omitted.

The received illumination light separation unit 20 in the detection apparatus 6 according to the sixth embodiment is a perforated mirror 20.

The variable power optical system 60 has an optical magnification β '(| β' | <1), and converts the parallel light beam having passed through the perforated mirror 20 and having the light beam diameter r6a into an illumination light beam having a light beam diameter r6b smaller than r6 a.

Specifically, by using the effective diameter r6a and the optical magnification β' of the variable power optical system 60, the light beam diameter r6b is expressed by the following expression (20).

[ mathematical expression 20]

r6b＝r6a×|β′|···(20)

The beam diameter r6b of the illumination beam having passed through the variable power optical system 60 is smaller than the effective diameter of the driven mirror 30.

The parallel light beam that has been emitted from the light source forming unit 10 and has the beam diameter r6a passes through the perforated mirror 20 and is converted into the illumination light beam having the beam diameter r6b by the variable power optical system 60. The illumination beam is deflected by the driven mirror 30 and becomes an illumination beam having a beam diameter r6c on the emission surface via the telescope 40 to illuminate an object outside the detection apparatus 6.

The light beam, which comprises the reflected light beam reflected by the illuminated object and has an effective diameter (i.e., the effective emitting diameter of the telescope 40) r6 c', is then re-entered from the emitting surface of the telescope 40. The re-entered beam travels through the telescope 40 and is deflected by the driven mirror 30 to become a beam having a beam diameter r6 b'. The deflected beam is then converted by the variable power optical system 60 into a received beam having a beam diameter r6a 'greater than r6 b'. The reception light beam is deflected in a direction different from the direction of the illumination light beam at the perforated mirror 20 to be received by the light receiving unit 50.

Then, the control unit 100 measures the difference between the light receiving time acquired in the light receiving element 52 and the light emitting time of the light source 11, or the difference between the phase of the received light signal acquired in the light receiving element 52 and the phase of the output signal from the light source 11. The difference is multiplied by the speed of light to determine the distance to the object.

As shown in fig. 13, in the detection apparatus 6 according to the sixth embodiment, the driven mirror 30 is driven at high speed, and therefore, in view of weight, the driven mirror 30 is required to have a small diameter, with the result that the effective diameter of the light beam deflected by the driven mirror 30 is naturally small. Thus, the driven mirror 30 easily limits the effective diameter of the light beam including the reflected light beam from the illuminated object.

Thus, the effective diameter r6 b' of the light beam can be considered to be equal to the effective diameter of the driven mirror 30.

As shown in fig. 13, by using the effective diameter r6b ' of the reflected light and the optical magnification β ' of the variable power optical system 60, the beam diameter r6a ' of the light beam entering the perforated mirror 20 from the variable power optical system 60 is expressed by the following expression (21).

[ mathematical expression 21]

When the diameter of the opening formed in the perforated mirror 20 is set to H, the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio R at which a part of the received light beam is lost due to the perforated mirror 20) is expressed by the following expression (22).

[ mathematical expression 22]

When the variable power optical system 60 is not provided as described in the fifth embodiment with reference to fig. 11, the beam diameter r6a 'of the light beam entering the perforated mirror 20 from the driven mirror 30 is equal to the effective diameter of the driven mirror 30, that is, the effective diameter r6 b' of the light beam.

When the beam diameter of the parallel light beam emitted from the light source forming unit 10 is r6a and the beam diameter of the parallel light beam having passed through the perforated mirror 20 and entered the driven mirror 30 is r6b, r6a is equal to r6 b.

In this case, the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio R' at which a part of the received light is lost due to the perforated mirror 20) is expressed by the following expression (23).

[ mathematical expression 23]

According to expression (22) and expression (23), the ratio of the loss ratio R to R' is expressed by the following expression (24).

[ mathematical expression 24]

Therefore, the inclusion of the variable power optical system 60 enables the detection apparatus 6 according to the sixth embodiment to reduce the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio of the received light due to the perforated mirror 20) (β')²And (4) doubling.

In the detection device 6 according to the sixth embodiment, the angle θ at which the light beam from the object enters the surface of the driven mirror 30 when the driven mirror 30 is stationary is used_SMCAnd an optical magnification β' of the variable power optical system 60, a viewing angle θ at which the light beam enters the perforated mirror 20 from the variable power optical system 60 when the driven mirror is at rest_SMC' is expressed by the following expression (25).

[ mathematical expression 25]

θ′_SMC＝θ_SMC×|β′|···(25)

The optical power β' of the variable power optical system 60 is less than 1, and thus θ_SMC' less than theta_SMC. This means that by providing light of variable powerIn the optical system 60, the incident image height of the received light beam on the light collecting surface (i.e., on the light receiving surface 52D) from the light collecting optical system 51 of the maximum angle of view is reduced.

Thus, the presence of the variable power optical system 60 requires the focal length f of the light collection optical system 51_cIs lengthened.

However, in the detection apparatus 6 according to the sixth embodiment, the length of the optical path from the perforated mirror 20 to the light receiving surface 52D of the light receiving element 52 can be shortened due to the re-imaging optical system 56 provided between the light collecting optical system 51 and the light receiving element 52.

Thus, the detection device 6 has another effect in that an increase in the size of the device due to the presence of the variable power optical system 60 is prevented by providing the re-imaging optical system 56.

In the detection apparatus 6 according to the sixth embodiment, the collimator 12 converts a divergent light beam emitted from the light source 11 in the light source forming unit 10 into a parallel light beam having a light beam diameter r6a smaller than the opening diameter H of the perforated mirror 20. However, the detection device 6 is not limited thereto, and a diaphragm may be provided between the light source forming unit 10 and the perforated mirror 20.

The light source forming unit 10 constituted only by the light source 11 and the collimator 12 in the detection apparatus 6 according to the sixth embodiment is not limited thereto. When the angle of divergence from the light source 11 is asymmetric, a cylindrical lens or the like may be provided in the light source forming unit 10 to shape the divergent light beam emitted from the light source 11 and then adjust the beam diameter with the provided diaphragm.

Here, it is important to keep the light quantity of the illumination light beam from the detection device at or below the upper limit determined in consideration of safety to the human eye, and the effective diameter of the illumination light beam can be determined in the light source forming unit 10 by using the diaphragm.

As described above, according to the detection apparatus 6 of the sixth embodiment, by providing the variable power optical system 60 between the perforated mirror 20 and the driven mirror 30, the light receiving efficiency at the perforated mirror 20 can be improved, and most of the reflected and scattered light beams from the illuminated distant object can be taken. Further, by providing the re-imaging optical system 56 between the field stop 55 and the light receiving element 52, the reception light beam can be efficiently received irrespective of the position of the light receiving surface 52D of the light receiving element 52, and an increase in the size of the apparatus can also be prevented.

Seventh embodiment

Fig. 14 is a schematic cross-sectional view of a detection device 7 according to a seventh embodiment of the present invention. In fig. 14, the optical path for illumination and the optical path for light reception are illustrated separately.

The detection device 7 according to the seventh embodiment has a configuration similar to that of the detection device 5 according to the fifth embodiment, and the same members in the detection device 7 as those in the detection device 5 are denoted by the same reference numerals so that the description of the members is omitted.

The parallel light beam which has been emitted from the light source forming unit 10 and has the beam diameter r7a passes through the received illumination light separating unit 20, is deflected by the driven mirror 30, and becomes an illumination light beam having the beam diameter r7b on the emission surface via the telescope 40 to illuminate an object outside the detection device 7.

The light beam, which comprises the reflected light beam reflected by the illuminated object and has an effective diameter (i.e., the effective emitting diameter of the telescope 40) r7 b', is then re-entered from the emitting surface of the telescope 40. The re-entered beam travels through the telescope 40 and is deflected by the driven mirror 30 to become a beam having a beam diameter r7 a'. The deflected light beams are deflected in a direction different from the direction of the illumination light beams in the reception illumination light separation unit 20 to be received by the light reception unit 50.

The control unit 100 measures the difference between the light reception time acquired in the light receiving element 52 and the light emission time of the light source 11, or the difference between the phase of the received light signal acquired in the light receiving element 52 and the phase of the output signal from the light source 11. The difference is multiplied by the speed of light to determine the distance to the object.

As shown in fig. 14, in the detection apparatus 7 according to the seventh embodiment, the driven mirror 30 is driven at high speed, and therefore, in view of weight, the driven mirror 30 is required to have a small diameter, with the result that the effective diameter of the light beam deflected by the driven mirror 30 is naturally small. Thus, the driven mirror 30 easily limits the effective diameter of the light beam including the reflected light beam from the illuminated object.

By using the effective diameter r7a 'of the driven mirror 30 and the optical magnification β (| β | >1) of the telescope 40, the effective diameter r7 b' of the light beam re-entering from the emission surface of the telescope 40 is expressed by the following expression (26).

[ mathematical expression 26]

r7b′＝r7a′×|β|···(26)

As shown in fig. 14, the effective diameter r7b 'of the light beam is | β | (>1) times the effective diameter r7 a' of the driven mirror 30. Thus, the detection apparatus 7 according to the seventh embodiment can receive more reflected and scattered light beams from the object than when the telescope 40 is not provided.

By using the deflection angle θ 1 of the principal ray of the parallel light beam deflected by the driven mirror 30 and the optical magnification β of the telescope 40, the deflection angle θ 2 of the principal ray of the illumination light beam emitted from the telescope 40 is expressed by the following expression (27).

[ mathematical expression 27]

As shown in fig. 14, since the optical magnification β of the telescope 40 is larger than 1, the deflection angle θ 2 of the principal ray of the illumination light beam is smaller than the deflection angle θ 1 of the principal ray of the parallel light beam deflected by the driven mirror 30.

Therefore, in the detection apparatus 7 according to the seventh embodiment, the angle of view is narrow, but the detection interval is also narrow, with the result that the detection resolution can be improved.

As described in the fourth embodiment with reference to fig. 9, the distance from the detection device 7 to the object 200 is set to p, where the area where the object 200 is illuminated is set toAnd a light beam received on the emitting surface of the telescope 40Is set to be theta_STC。

Maximum angle of view theta of the light beam when received on the emitting surface of the telescope 40_STCThe light receiving element 52 also receives unnecessary light, such as light beams from outside the viewing angle and scattered light beams generated outside the viewing angle and inside the apparatus, when the viewing angle of the object 200 to be illuminated is larger.

Therefore, it is preferable to configure the detection device 7 according to the seventh embodiment so that the following expression (28) is satisfied.

[ mathematical expression 28]

As shown in fig. 10, the angle at which the light beam from the object 200 enters the surface of the driven mirror 30 when the driven mirror 30 is stationary is set to θ_SMCAt the same time, the angle θ is adjusted by using the optical magnification β of the telescope 40_SMCExpressed by the following expression (29).

[ mathematical expression 29]

θ_SMC＝θ_STC×|β|···(29)

Thus, when the focal length of the light collection optical system 51 is set to fc, the image height y of the light beam collected on the light receiving surface of the light receiving element 52 when the driven mirror 30 is stationary from the maximum angle of view_RExpressed by the following expression (30).

[ mathematical expression 30]

y_R＝fc×tanθ_SMC···(30)

For simplicity, the re-imaging optical system 56 is omitted here.

Thus, the effective light receiving diameter D of the light receiving element 52 is set so that the following expression (31) is satisfied in order to efficiently receive the light beam from the object 200, that is, in order to avoid receiving unnecessary light.

[ mathematical expression 31]

D≤2×y_R···(31)

In practice, adjustment of the focal length fc of the light collection optical system 51 is more often selected for the purpose of versatility rather than the limitation of the effective light receiving diameter D of the light receiving element, and there is a case where the effective light receiving diameter D cannot be designed to satisfy expression (31).

In this case, by providing the field stop 55 at the light collection point of the light collection optical system 51, the light reception angle of view of the light receiving element 52 can be limited to a desired angle of view.

When the aperture diameter of the field stop 55 is set to P_stDiameter P of hole_stIs designed to satisfy the following expression (32).

[ mathematical expression 32]

P_st≤2×y_R···(32)

By setting the field stop 55 in this way, even when the effective light receiving diameter D cannot be designed to satisfy expression (31), it is possible to receive only the light beam from a desired angle of view. Therefore, it is possible to suppress reception of unnecessary light such as light beams from other viewing angles and light beams reflected or scattered inside the apparatus.

In the seventh embodiment, expression (32) is set as the hole diameter P for the field stop 55 having a single light beam_stThe conditions of (1). However, in practice, the spot diameter at the light collection point is also required to be considered, and for the purpose of receiving a large amount of light, it may be the aperture diameter P of the field stop 55_stA range slightly wider than expression (32) is set.

It is desirable that about half of the received light beam at the viewing angle is blocked by the aperture stop and the amount of received light outside the optical axis is halved accordingly. However, when the spot diameter at the hole portion is large, the amount of received light outside the optical axis slowly decreases and most of the received light beams outside the angle of view are also received, with the result that the S/N ratio is poor with respect to the amount of received light inside the optical axis. Thus, the size of the object is incorrectly determined.

Thus, it is important to suppress reception of unnecessary light while acquiring most of the reflected light beam in a manner of balancing acquisition of most of the reflected light beam with suppression of reception of unnecessary light. Thus, look atHole diameter P of field stop 55_stIs determined such that taking a balance between the majority of the reflected light beam and suppressing reception of unnecessary light results in the greatest improvement in the quality of the received light signal.

Although the illumination area, the light receiving angle of view, and the like are regarded as circular in the description given above, the aperture of the field stop 55 may have a rectangular or elliptical shape depending on the illumination shape, the light receiving angle of view to be detected, or other factors.

In this way, it is possible to appropriately block unnecessary light while acquiring a large part of the reflected light beams from the object, and as a result, it is possible to measure the distance of the object from a longer distance with improved distance measurement accuracy. Since the angle of view is limited, the detection resolution in the detection of the size of the object can also be improved.

In the detection apparatus 7 according to the seventh embodiment, for reasons given below, a re-imaging optical system 56 is provided between the field stop 55 and the light receiving element 52, as shown in fig. 14.

In the detection device 7, the light receiving surface 52D of the light receiving element 52 and the field stop 55 are desirably arranged adjacent to each other.

However, when the light receiving surface 52D is inside the light receiving element 52, the numerical aperture NA of the light collection optical system 51 is too large in terms of the holding performance, and therefore there are cases in which not all of the collected light beams can be received by the light receiving element 52.

As described in the fifth embodiment with reference to fig. 12A, when the light receiving surface 52D is closer to the inside than the holding unit (not shown) such as the light receiving element 52, the collected light beam having passed through the field stop 55 is spread on the light receiving surface 52D behind the field stop 55 to be wider than the surface area of the light receiving surface 52D. Therefore, the light beam illustrated as a hatched portion is not received.

As understood from expression (17) and expression (19), this can be achieved by extending the focal length f of the light collection optical system 51_cTo prevent it. However, in that case, as shown in fig. 12B, the optical path behind the light collection optical system 51 isThis increases the size of the device.

As shown in fig. 12C, the detection apparatus 7 according to the seventh embodiment solves this problem by providing a re-imaging optical system 56 between the field stop 55 and the light receiving element 52. This forms an image of the field stop 55 on the light receiving surface 52D of the light receiving element 52, and thus can prevent the loss of the light beam in the above-mentioned hatched portion representing the portion of the light beam that cannot be received.

As described above, according to the detection apparatus 7 of the seventh embodiment, by providing the re-imaging optical system 56 between the field stop 55 and the light receiving element 52, the reflected light beam can be efficiently received irrespective of the position of the light receiving surface 52D of the light receiving element 52, and also an increase in the size of the apparatus can be prevented.

In the detection apparatus 7 according to the seventh embodiment, the angle of the driven mirror 30 is set (tilted) and the telescope 40 is made eccentric so that the optical path of the principal ray of the illumination beam at the central view angle within the range of the scanning view angle of the driven mirror 30 does not coincide with the optical axis Ax of the telescope 40, as described in the first embodiment with reference to fig. 2A and in the second embodiment with reference to fig. 4, 5B, and 6B.

The detection apparatus 7 according to the seventh embodiment also has a configuration in which the light receiving element 52 or the re-imaging optical system 56 is decentered or tilted so that the center position of the light receiving surface 52D of the light receiving element 52 or the optical axis of the re-imaging optical system 56 does not fall on the optical axis of the detection apparatus 7, as described below.

In other words, the detection apparatus 7 according to the seventh embodiment has a configuration in which the light receiving element 52 or the re-imaging optical system 56 is decentered or tilted so that the center position of the light receiving surface 52D of the light receiving element 52 or the optical axis of the re-imaging optical system 56 does not fall on the optical path of the principal ray of the light beam at the center view angle within the range of the scanning angle of view of the driven mirror 30, as described below.

Fig. 15A is a partially enlarged view of the detection device of the comparative example. Fig. 15B, 15C, and 15D are partially enlarged views of the detection device 7 according to the seventh embodiment.

The center position of the light receiving surface 52D of the light receiving element 52 is set to AXR', the optical axis of the re-imaging optical system 56 is set to AXR ", and the optical axis of the detection device 7 is set to AXR.

In the detection apparatus of the comparative example shown in fig. 15A, the center position AXR' of the light receiving surface 52D of the light receiving element 52 and the optical axis AXR ″ of the re-imaging optical system 56 fall on the optical axis AXR of the detection apparatus 7 (are not eccentric).

As shown in fig. 15A, the light beam from the object is collected by the light collection optical system 51, passes through the field stop 55, and is collected again to the central portion of the light receiving surface 52D by the re-imaging optical system 56.

As shown in fig. 15A, the unnecessary light is collected once on the virtual plane RF _ P in front of the field stop 55 via the light collection optical system 51, and then is blurry-diffused on the field stop 55. A part of the unnecessary light passes through the field stop 55, is collected again on the virtual plane RF _ P' by the re-imaging optical system 56, and then reaches the light receiving surface 52D.

Fig. 16 is a diagram for illustrating the positional relationship between the reflected light regions RF1G and RF2G formed on the light receiving surface 52D of the light receiving element 52 observed in this case. The reflected light region RF2G partially overlaps the light receiving surface 52D due to unnecessary light, and this also depends on the decentering direction of the telescope 40.

In fig. 15B, the light receiving element 52 in the detection device 7 according to the seventh embodiment is decentered so that the center position AXR' of the light receiving surface 52D of the light receiving element 52 is deviated from the optical axis AXR of the detection device 7.

As shown in fig. 15B, the reflected light beam from the object is received on the light receiving surface 52D. On the other hand, unnecessary light travels outside the light receiving surface 52D and is thus not received.

In fig. 15C, the light receiving element 52 in the detection device 7 according to the seventh embodiment is eccentric and shifted to the virtual plane RF _ P 'so that the center position AXR' of the light receiving surface 52D of the light receiving element 52 is deviated from the optical axis AXR of the detection device 7.

As described above, the unnecessary light is collected on the virtual plane RF _ P ', and the surface area of the unnecessary light on the light receiving surface 52D of the light receiving element 52 shifted onto the virtual plane RF _ P' is small. Thus, unless the reflected light beam from the object is too blurred on the light receiving surface 52D, the reflected light beam is easily separated from the unnecessary light.

In fig. 15D, the re-imaging optical system 56 in the detection apparatus 7 according to the seventh embodiment is decentered so that the optical axis AXR ″ of the re-imaging optical system 56 does not coincide with the optical axis AXR of the detection apparatus 7.

As shown in fig. 15D, decentering of the re-imaging optical system 56 also causes unnecessary light to travel outside the light receiving range of the light receiving surface 52D to ensure that the unnecessary light is not received while the reflected light beam from the object is received on the light receiving surface 52D.

As described above, according to the detection apparatus 7 of the seventh embodiment, it is possible to prevent the reception of unnecessary light by decentering or tilting of the light receiving element 52 or the re-imaging optical system 56 so that the center position of the light receiving surface 52D of the light receiving element 52 or the optical axis of the re-imaging optical system 56 does not fall on the optical axis of the detection apparatus 7 (in other words, the optical path of the principal ray of the light beam at the center view angle within the range of the scanning angle of view of the driven mirror 30).

Eighth embodiment

Fig. 17 is a schematic cross-sectional view of a detecting unit 8 according to an eighth embodiment of the present invention. In fig. 17, an optical path for illumination and an optical path for light reception are separately illustrated.

The detection apparatus 8 according to the eighth embodiment has a configuration similar to that of the detection apparatus 7 according to the seventh embodiment except that a variable power optical system 60 is newly provided, and the same members in the detection apparatus 8 as those in the detection apparatus 7 are denoted by the same reference numerals so that the description of the members is omitted.

The received illumination light separation unit 20 in the detection apparatus 8 according to the eighth embodiment is a perforated mirror 20.

The variable power optical system 60 has an optical magnification β '(| β' | <1), and converts the parallel light beam having passed through the perforated mirror 20 and having the light beam diameter r8a into an illumination light beam having a light beam diameter r8b smaller than r8 a.

Specifically, by using the effective diameter r8a and the optical magnification β' of the variable power optical system 60, the light beam diameter r8b is expressed by the following expression (33).

[ mathematical expression 33]

r8b＝r8a×|β′|···(33)

The beam diameter r8b of the illumination beam having passed through the variable power optical system 60 is smaller than the effective diameter of the driven mirror 30.

The parallel light beam that has been emitted from the light source forming unit 10 and has the beam diameter r8a passes through the perforated mirror 20 and is converted into an illumination light beam having the beam diameter r8b by the variable power optical system 60. The illumination beam is deflected by the driven mirror 30 and becomes an illumination beam having a beam diameter r8c on the emission surface via the telescope 40 to illuminate an object outside the detection apparatus 8.

The light beam, which comprises the reflected light beam reflected by the illuminated object and has an effective diameter (i.e., the effective emitting diameter of the telescope 40) r8 c', is then re-entered from the emitting surface of the telescope 40. The re-entered beam travels through the telescope 40 and is deflected by the driven mirror 30 to become a beam having a beam diameter r8 b'. The deflected light beam is converted by the variable power optical system 60 into a received light beam having a beam diameter r8a 'greater than r8 b'. The reception light beam is deflected in a direction different from the direction of the illumination light beam at the perforated mirror 20 to be received by the light receiving unit 50.

Then, the control unit 100 measures the difference between the light receiving time acquired in the light receiving element 52 and the light emitting time of the light source 11, or the difference between the phase of the received light signal acquired in the light receiving element 52 and the phase of the output signal from the light source 11. The difference is multiplied by the speed of light to determine the distance to the object.

As shown in fig. 17, in the detection apparatus 8 according to the eighth embodiment, the driven mirror 30 is driven at high speed, and therefore the driven mirror 30 is required to have a small diameter in view of weight, with the result that the effective diameter of the light beam deflected by the driven mirror 30 is naturally small. Thus, the driven mirror 30 easily limits the effective diameter of the light beam including the reflected light beam from the illuminated object.

Thus, the effective diameter r8 b' of the light beam can be considered to be equal to the effective diameter of the driven mirror 30.

As shown in fig. 17, the beam diameter r8a ' of the light beam entering the perforated mirror 20 from the variable power optical system 60 is expressed by the following expression (34) by using the effective diameter r8b ' of the light beam and the optical magnification β ' of the variable power optical system 60.

[ mathematical expression 34]

When the diameter of the opening formed in the perforated mirror 20 is set to H, the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio R at which a part of the received light beam is lost due to the perforated mirror 20) is expressed by the following expression (35).

[ mathematical expression 35]

When the variable power optical system 60 is not provided as described in the seventh embodiment with reference to fig. 14, the beam diameter r8a 'of the light beam entering the perforated mirror 20 from the driven mirror 30 is equal to the effective diameter of the driven mirror 30, that is, the effective diameter r8 b' of the light beam.

When the beam diameter of the parallel light beam emitted from the light source forming unit 10 is r8a and the beam diameter of the parallel light beam passing through the perforated mirror 20 and then entering the driven mirror 30 is r8b, r8a is equal to r8 b.

In this case, the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio R' at which a part of the received light beam is lost due to the perforated mirror 20) is expressed by the following expression (36).

[ mathematical expression 36]

Therefore, according to expression (35) and expression (36), the ratio of the loss ratio R to R' is expressed by the following expression (37).

[ mathematical expression 37]

Therefore, the inclusion of the variable power optical system 60 enables the detection apparatus 8 according to the eighth embodiment to reduce the proportion of the amount of light that cannot be received as a received signal by the light receiving unit 50 due to the perforated mirror 20 (i.e., the loss ratio of the received light due to the perforated mirror 20) (β')²And (4) doubling.

In the detection apparatus 8 according to the eighth embodiment, the angle θ at which the light beam from the object enters the surface of the driven mirror 30 when the driven mirror 30 is stationary is used_SMCAnd an optical magnification β' of the variable power optical system 60, a viewing angle θ at which the light beam enters the perforated mirror 20 from the variable power optical system 60 when the driven mirror is at rest_SMC' is expressed by the following expression (38).

[ mathematical expression 38]

θ′_SMC＝θ_SMC×β′··.(38)

The optical power β' of the variable power optical system 60 is less than 1, and thus θ_SMC' less than theta_SMC. This means that by providing the variable power optical system 60, the incident image height of the received light beam on the light collecting surface of the light collecting optical system 51 from the maximum angle of view (i.e., on the light receiving surface 52D) is reduced.

Thus, the presence of the variable power optical system 60 requires the focal length f of the light collection optical system 51_cIs lengthened.

However, in the detection apparatus 8 according to the eighth embodiment, the length of the optical path from the perforated mirror 20 to the light receiving surface 52D of the light receiving element 52 can be shortened due to the re-imaging optical system 56 provided between the light collecting optical system 51 and the light receiving element 52.

Therefore, the detection device 8 has another effect in that an increase in the size of the device due to the presence of the variable power optical system 60 is prevented by providing the re-imaging optical system 56.

In the detection apparatus 8 according to the eighth embodiment, the collimator 12 converts a divergent light beam emitted from the light source 11 in the light source forming unit 10 into a parallel light beam having a light beam diameter r8a smaller than the opening diameter H of the perforated mirror 20. However, the detection device 8 is not limited thereto, and a diaphragm may be provided between the light source forming unit 10 and the perforated mirror 20.

The light source forming unit 10 constituted only by the light source 11 and the collimator 12 in the detection apparatus 8 according to the eighth embodiment is not limited thereto. When the angle of divergence from the light source 11 is asymmetric, a cylindrical lens or the like may be provided in the light source forming unit 10 to shape the divergent light beam emitted from the light source 11, followed by adjusting the beam diameter with the provided diaphragm.

Here, it is important to keep the light quantity of the illumination light beam from the detection device at or below the upper limit determined in consideration of safety to the human eye, and the effective diameter of the illumination light beam can be determined in the light source forming unit 10 by using the diaphragm.

As described above, according to the detection device 8 of the eighth embodiment, the light receiving efficiency at the perforated mirror 20 can be improved, and most of the reflected and scattered light beams from the illuminated distant object can be taken by providing the variable power optical system 60 between the perforated mirror 20 and the driven mirror 30. Further, by providing the re-imaging optical system 56 between the field stop 55 and the light receiving element 52, the reception light beam can be efficiently received irrespective of the position of the light receiving surface 52D of the light receiving element 52, and an increase in the size of the apparatus can also be prevented. It is also possible to prevent the reception of unnecessary light by decentering or tilting the light receiving element 52 or the re-imaging optical system 56 so that the center position of the light receiving surface 52D of the light receiving element 52 or the optical axis of the re-imaging optical system 56 does not fall on the optical axis of the detection device 8 (in other words, the optical path of the principal ray of the light beam at the central view angle within the range of the scanning view angle of the driven mirror 30).

This concludes the description of the detection apparatus according to the embodiment. However, the present invention is not limited to these embodiments, and various changes and modifications may be made thereto.

As described above, in the detection apparatus according to the embodiment of the present invention, the driven mirror and the telescope are arranged so that the central angle of view within the driving range of the driven mirror does not fall on the optical axis of the telescope. Specifically, in the reflected and scattered light beams from the optical element included in the telescope, the frequently generated reflected and scattered light beams around the optical axis can be kept off the center of the light receiving surface by tilting the driven mirror.

The telescope is also eccentric in a direction perpendicular to the optical axis to deviate the incident point of the illumination light beam entering the driven mirror from the optical axis of the telescope, thereby dispersing the reflected light beam from the optical element included in the telescope in various directions and splitting (blurring) unnecessary light entering the light receiving unit.

This enables the detection apparatus to disperse strong unnecessary light near the optical axis of the telescope or to shift the angle of view at which the unnecessary light is generated from the center of the light receiving surface, and by selecting an appropriate angle of view, it is possible to prevent reception of unnecessary light within the range of angles of view required to detect and measure the reflected light beam from the object.

By arranging the telescope, tilting the driven mirror, and decentering the telescope in this manner, it is possible to prevent unnecessary light from being received while receiving a large part of the reflected and scattered light beams from the object. Therefore, a detection device capable of finely detecting a distant object can be obtained.

The detection device according to the embodiment of the present invention is particularly applicable as a detection device for remote ranging of an automatic machine and a sensor for automatic driving as described below.

< vehicle-mounted System >

Fig. 18 is a diagram of the configuration of an in-vehicle system (driving assist device) 600 including the detection device 1 according to one of the first to eighth embodiments described above.

The in-vehicle system 600 is a device that is installed in an automobile or other type of vehicle to assist driving of the vehicle based on image information about the surroundings of the vehicle obtained by the detection device 1.

As shown in fig. 18, the in-vehicle system 600 includes the detection apparatus 1 according to one of the first to eighth embodiments described above, a collision determination unit 70, a vehicle information acquisition device 80, a control device (electronic control unit: ECU)90, and an alarm device 95.

FIG. 19 is a schematic diagram of a vehicle 700 including an on-board system 600.

A case in which the detection range 300 of the detection apparatus 1 is set to a space in front of the vehicle 700 is illustrated in fig. 19. The detection range 300 may be set as a space behind the vehicle 700.

The detection apparatus 1 installed inside the vehicle 700 in fig. 19 may be installed outside the vehicle 700.

Fig. 20 is a flowchart for illustrating an example of the operation of the in-vehicle system 600 according to the embodiment of the present invention.

The operation of the in-vehicle system 600 is described below by following a flowchart.

In step S1, an object (subject) in the surrounding environment of the vehicle is detected by using the detection device 1, and information on the distance to the object (distance information) is acquired.

In step S2, the vehicle information is acquired from the vehicle information acquisition device 80. The vehicle information is information including the speed, yaw rate, steering angle, and the like of the vehicle.

In step S3, the collision determination unit 70 determines whether the distance information acquired by the detection device 1 indicates a distance included in a preset distance range. In this way, the collision determination unit 70 determines whether an obstacle is present in the surrounding environment within a set distance from the vehicle to determine the possibility of a collision between the vehicle and the obstacle.

When an obstacle exists within the set distance (yes in step S3), the collision determination unit 70 determines that there is a possibility of collision (step S4). When no obstacle exists within the set distance (no in step S3), the collision determination unit 70 determines that there is no possibility of collision (step S5).

Next, when it is determined that there is a possibility of collision, the collision determination unit 70 notifies the control device 90 and the alarm device 95 of the result of the determination. At this time, the control device 90 controls the vehicle based on the result of the determination made by the collision determination unit 70, and the alarm device 95 issues an alarm based on the result of the determination made by the collision determination unit 70.

For example, the control apparatus 90 performs control such as braking, stopping acceleration, or suppressing the output of the engine or motor on the vehicle by generating a control signal for generating braking power in each wheel.

The alarm device 95 issues an alarm to a user (driver) of the vehicle by, for example, issuing an alarm sound (warning), such as a sound, displaying alarm information on a screen of a car navigation system or the like, or vibrating a seat belt or a steering wheel.

According to the in-vehicle system 600 of this embodiment, an obstacle can be effectively detected by the above-described processing, and thus a collision between the vehicle and the obstacle can be avoided. In particular, by applying the detection apparatus according to the above-described embodiment to the in-vehicle system 600, it is possible to perform obstacle detection and collision determination with high accuracy.

The in-vehicle system 600 applied to the driving assistance (collision damage reduction) in this embodiment is not limited thereto, and may be applied to cruise control (including adaptive cruise control), automatic driving, and the like. The in-vehicle system 600 is also not limited to automobiles and the like, and is applicable to moving objects (mobile devices), such as ships, airplanes, or industrial robots. The in-vehicle system 600 is also not limited to the detection apparatus 1 and the moving object according to the embodiment of the present invention, and may be applied to various types of equipment using object recognition, such as an Intelligent Transportation System (ITS).

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of japanese patent application No.2018-001405, filed on 2018, 1, 9, which is incorporated herein by reference in its entirety.

[ list of reference numerals ]

1 detection device

11 light source

20 separating unit (separating unit) for receiving illumination light

30 driven mirror (deflection unit)

40 telescope (first telescope)

52 light receiving element

200 object