阅读说明：本技术 激光干涉装置及应用该激光干涉装置的三维重建成像系统 (Laser interference device and three-dimensional reconstruction imaging system applying same ) 是由 吴庆阳 卢晓婷 黄浩涛 于 2019-09-02 设计创作，主要内容包括：本发明涉及一种激光干涉装置及应用该激光干涉装置的三维重建成像系统,该激光干涉装置包括激光器、反射镜以及鱼眼采集器,其中,所述反射镜包括第一圆锥反射镜和第二圆锥反射镜,所述第一圆锥反射镜的底部嵌入所述第二圆锥反射镜的顶部,并且所述第一圆锥反射镜的锥角小于所述第二圆锥反射镜的锥角；所述激光器射出的锥形光线依次经过所述第一圆锥反射镜和所述第二圆锥反射镜形成条纹。通过锥角不同的第一圆锥反射镜和第二圆锥反射镜,使得经过反射镜上的光束发生干涉,从而在待测物上产生稠密的条纹,再通过鱼眼采集器实现大视场数据采集,从而提高成像的精度。该结构设计巧妙、结构简单、价格低。(The invention relates to a laser interference device and a three-dimensional reconstruction imaging system using the same, wherein the laser interference device comprises a laser, a reflector and a fisheye collector, wherein the reflector comprises a first conical reflector and a second conical reflector, the bottom of the first conical reflector is embedded into the top of the second conical reflector, and the cone angle of the first conical reflector is smaller than that of the second conical reflector; the conical light emitted by the laser sequentially passes through the first conical reflector and the second conical reflector to form stripes. Through the first conical reflector and the second conical reflector with different cone angles, light beams passing through the reflectors interfere, dense stripes are generated on an object to be detected, and then the large-field data acquisition is realized through the fisheye acquisition device, so that the imaging precision is improved. The structure has the advantages of ingenious design, simple structure and low price.)

1. A laser interference device is used for collecting fringes on an object to be detected and is characterized by comprising a laser, a reflector and a fisheye collector, wherein the reflector comprises a first conical reflector and a second conical reflector, the bottom of the first conical reflector is embedded into the top of the second conical reflector, and the cone angle of the first conical reflector is smaller than that of the second conical reflector; the laser device comprises a first conical reflector, a second conical reflector, a fisheye collector and a laser device, wherein the first conical reflector and the second conical reflector are arranged on the laser device, the conical light emitted by the laser device sequentially passes through the first conical reflector and the second conical reflector to form stripes, the stripes are reflected to an object to be detected, and the fisheye collector is used.

2. The laser interference device according to claim 1, wherein the fisheye collector is a fisheye lens, the fisheye lens faces the object to be measured, and the fisheye lens and the object to be measured are arranged at a preset distance.

3. The laser interference device according to claim 1, wherein the fisheye collector comprises a first fisheye lens and a second fisheye lens, and the first fisheye lens and the second fisheye lens are respectively used for collecting the fringes on the object to be measured.

4. The laser interference device according to claim 3, wherein the first fisheye lens is disposed facing the second fisheye lens; or the first fisheye lens and the second fisheye lens are arranged in the same direction and face the object to be detected.

5. The laser interference device according to claim 1, wherein the fisheye collector comprises a fisheye lens and a plane mirror, the fisheye lens is located between the mirror and the plane mirror, the fisheye lens is arranged facing the plane mirror, the side surface of the fisheye lens collects the fringes on the object to be measured, and the front surface of the fisheye lens collects the fringes on the object to be measured through the plane mirror.

6. The laser interference device of claim 1, wherein the first conical reflector and the second conical reflector are of an integral or split structure.

7. A laser interference device according to claim 1, wherein the centers of the laser and the mirror are located on the same line.

8. A three-dimensional reconstruction imaging system is characterized by comprising a processing device and the laser interference device of any one of claims 1 to 7, wherein the processing device is in signal connection with the fisheye collector, the fisheye collector sends the collected fringes to the processing device, and the processing device is used for generating a three-dimensional outline image of an object to be measured according to the fringes.

Technical Field

The invention relates to the technical field of imaging, in particular to a laser interference device and a three-dimensional reconstruction imaging system using the same.

Background

In the hot field of indoor robot navigation, automatic driving, unmanned aerial vehicles, indoor positioning, man-machine interaction and the like, how to acquire 360-degree dense three-dimensional point cloud data of the surrounding environment in real time is always a hotspot and a difficult problem of research of everyone. In the prior art, scanning and acquisition are generally performed by a multiline lidar, but this device has the following disadvantages: 1. the price is high; 2. 360-degree rotation scanning is required, so that the scanning efficiency is low; 3. the number of lines scanned is limited, resulting in failure to obtain dense three-dimensional point cloud data.

Disclosure of Invention

The invention mainly aims to provide a laser interference device and a three-dimensional reconstruction imaging system using the same, and aims to solve the technical problems that a multi-line laser radar is high in price, low in scanning efficiency and incapable of obtaining dense three-dimensional point cloud data in the prior art.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

a laser interference device is used for collecting fringes on an object to be detected and comprises a laser, a reflector and a fisheye collector, wherein the reflector comprises a first conical reflector and a second conical reflector, the bottom of the first conical reflector is embedded into the top of the second conical reflector, and the cone angle of the first conical reflector is smaller than that of the second conical reflector; the laser device comprises a first conical reflector, a second conical reflector, a fisheye collector and a laser device, wherein the first conical reflector and the second conical reflector are arranged on the laser device, the conical light emitted by the laser device sequentially passes through the first conical reflector and the second conical reflector to form stripes, the stripes are reflected to an object to be detected, and the fisheye collector is used.

The fisheye collector is a fisheye lens, the fisheye lens faces to an object to be detected, and the fisheye lens and the object to be detected are arranged at a preset distance.

The fisheye collector comprises a first fisheye lens and a second fisheye lens, and the first fisheye lens and the second fisheye lens are respectively used for collecting the stripes on the object to be detected.

Wherein the first fisheye lens is arranged facing the second fisheye lens; or the first fisheye lens and the second fisheye lens are arranged in the same direction and face the object to be detected.

Wherein, the fisheye collector includes fisheye lens and plane mirror, the fisheye lens is located the speculum with between the plane mirror, the fisheye lens towards the plane mirror sets up, on the determinand is gathered to the side of fisheye lens the stripe, the front of fisheye lens is passed through on the determinand is gathered to the plane mirror the stripe.

The first conical reflector and the second conical reflector are of an integrated or split structure.

Wherein, the centers of the laser and the reflecting mirror are positioned on the same straight line.

A three-dimensional reconstruction imaging system comprises a processing device and the laser interference device, wherein the processing device is in signal connection with a fisheye collector, the fisheye collector sends collected fringes to the processing device, and the processing device is used for generating a three-dimensional outline image of an object to be detected according to the fringes.

According to the laser interference device and the three-dimensional reconstruction imaging system using the same, light beams passing through the reflectors are interfered through the first conical reflector and the second conical reflector with different cone angles, dense stripes are generated on an object to be detected, and then large-field data collection is achieved through the fisheye collector, so that the imaging precision is improved. The structure has the advantages of ingenious design, simple structure and low price.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic perspective view of a laser interference device according to one embodiment of the present invention.

Fig. 2 is a schematic diagram of a PMP system in an embodiment in accordance with the invention.

Fig. 3 is a schematic diagram of a PMP system in an embodiment in accordance with the invention.

FIG. 4 is a schematic illustration of deformation of a stripe in accordance with an embodiment of the present invention.

Fig. 5 is an optical path diagram of a PMP system in an embodiment in accordance with the invention.

FIG. 6 is a phase shift diagram;

FIG. 6(a) is a phase shift plot of a stripe shifted by 0 pixels in the x-axis direction in accordance with one embodiment of the present invention;

FIG. 6(b) is a phase shift plot of a fringe shifted by 2 pixels in the x-axis direction in accordance with one embodiment of the present invention;

FIG. 6(c) is a phase shift diagram where the stripes are shifted by 4 pixels in the x-axis direction in one embodiment in accordance with the invention.

FIG. 7 is a phase diagram;

FIG. 7(a) is a truncated phase diagram of the deformed fringes according to one embodiment of the present invention;

fig. 7(b) is a continuous phase diagram of deformed fringes in one embodiment according to the present invention.

1. A laser interference device; 1. a laser; 2. a mirror; 21. a first conical mirror; 22. a second conical mirror; 3. a fish eye collector; 31. a fisheye lens; 32. a plane mirror; 4. an analyte.

Detailed Description

In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 is a schematic perspective view of a laser interference device according to one embodiment of the present invention.

As can be seen from the figure, the laser interference device 10 may have a laser 1, a reflector 2 and a fish eye collector 3, wherein the reflector 2 includes a first conical reflector 21 and a second conical reflector 22, the bottom of the first conical reflector 21 is embedded in the top of the second conical reflector 22, and the cone angle of the first conical reflector 21 is smaller than that of the second conical reflector 22; the conical light emitted by the laser 1 sequentially passes through the first conical reflector 21 and the second conical reflector 22 to form stripes, the stripes are reflected to the object to be detected 4, and the fisheye collector 3 is used for collecting the stripes on the object to be detected 4.

In this example, the light beams passing through the reflector 2 interfere with each other through the first conical reflector 21 and the second conical reflector 22 with different cone angles, so that dense stripes are generated on the object 4 to be measured, and then the large-field data acquisition is realized through the fisheye collector 3, so that the imaging precision is improved. The structure has the advantages of ingenious design, simple structure and low price.

In this embodiment, the fisheye collector 3 includes a fisheye lens 31 and a plane mirror 32, the fisheye lens 31 is located between the mirror 2 and the plane mirror 32, the fisheye lens 31 is disposed facing the plane mirror 32, the side surface of the fisheye lens 31 collects the stripes on the object to be measured 4, and the front surface of the fisheye lens 31 collects the stripes on the object to be measured 4 through the plane mirror 32. As shown in fig. 1, the side surface of the fisheye lens 31 is located obliquely above the object 4, and a part of the stripes on the object 4 can be collected through the side surface of the fisheye lens 31. The front surface of the fisheye lens 31 can collect the stripes of the rest part of the object 4 to be measured through the plane reflector 32, so that the fisheye lens 31 realizes the data collection of a large field of view. In addition, in the acquisition process of the fisheye lens 31, the stripes acquired from the side surface and the front surface do not interfere with each other, so that the imaging precision is improved.

In an alternative embodiment, the fisheye collector is a fisheye lens, and the fisheye lens faces the object to be detected, so that the stripes on the object to be detected are collected. The fisheye lens and the object to be detected are arranged at a preset distance, so that a space phase lookup table is established according to the distance between the fisheye lens and the object to be detected.

In other embodiments, the fisheye collector includes a first fisheye lens and a second fisheye lens, and the first fisheye lens and the second fisheye lens are respectively used for collecting stripes on the object to be measured. Through the mutual cooperation of the first fisheye lens and the second fisheye lens, the large-field-of-view data acquisition is realized.

Optionally, the first fisheye lens is arranged facing the second fisheye lens. The first fisheye lens and the second fisheye lens can be used for collecting stripes at different positions on the object to be detected, so that dense three-dimensional point cloud data can be obtained, and the imaging precision is further improved.

Optionally, the first fisheye lens and the second fisheye lens are arranged in the same direction and face the object to be measured. The first fisheye lens and the second fisheye lens can be used for collecting stripes at different positions on the object to be detected, so that dense three-dimensional point cloud data can be obtained, and the imaging precision is further improved.

In this embodiment, the first conical reflector 21 and the second conical reflector 22 are an integral structure, and it can be understood that in an alternative embodiment, the first conical reflector 21 and the second conical reflector 22 may also be a separate structure.

In the embodiment, the centers of the laser 1 and the reflector 2 are located on the same straight line, and the structural design is favorable for fringe phase shift and spatial phase calibration. It will be appreciated that in alternative embodiments, the centers of the laser 1 and the mirror 2 need not be collinear, but rather a spatial phase look-up table may be established prior to reconstruction of the three-dimensional profile.

In the present embodiment, the viewing angle of the fisheye lens is 220 degrees. It is understood that in alternative embodiments, the viewing angle of the fisheye lens is not limited to 220 degrees, and may be determined according to actual requirements.

It can be understood that the laser interference device using the monocular lens performs three-dimensional reconstruction through phase profilometry, and the laser interference device using the binocular lens performs three-dimensional reconstruction through the positional relationship between the binocular lenses.

The working principle is as follows:

the laser emits laser beams, the beams are slowly changed into cone-shaped beams from linear beams in the forward flying process, because the cone angles of the first conical reflector and the second conical reflector are different, the beams passing through the first conical reflector and the second conical reflector are reflected at different angles, the reflected beams are interfered with each other, and therefore stripes are formed on an object to be detected. By moving the laser back and forth, the fringes are phase shifted and the truncated phase profile is obtained from the phase shift map.

In this embodiment, the three-dimensional reconstruction imaging system may have a processing device and a laser interference device in any of the foregoing embodiments, the processing device is in signal connection with a fisheye collector, the fisheye collector sends the collected fringes to the processing device, and the processing device is configured to generate a three-dimensional contour image of the object to be measured according to the fringes.

In this embodiment, the processing device and the fisheye collector are connected by wireless signals. It will be appreciated that in alternative embodiments, the processing device and the fish-eye collector may also be connected by wire.

The binocular three-dimensional reconstruction imaging system can be known, and in the reconstruction process, only the relation between the binoculars needs to be determined, so that the requirement on the assembly of the whole system is not high, the assembly difficulty is reduced, and the imaging precision is further ensured. In this embodiment, the processing device generates a three-dimensional profile image of the object according to Phase Measurement Profilometry (PMP), and the principle of the phase measurement profilometry and the process of reconstructing the three-dimensional profile image will be described in detail below.

Principle of phase profilometry:

phase Measurement Profilometry (PMP) is a non-contact three-dimensional sensing method that uses sinusoidal fringe projection and digital phase shift techniques to acquire and process large amounts of three-dimensional data at high speed and accuracy based on inexpensive optical, electronic, and digital hardware devices. When a sine stripe pattern is projected on the surface of a three-dimensional diffuse reflection object, the deformed stripe modulated by the surface shape of the object can be obtained from an imaging system, N (N is more than or equal to 3) deformed light field images are obtained by utilizing a discrete phase shift technology, the phase distribution is calculated according to an N-step phase shift algorithm, and the phase distribution is calculated from the phase of phase shiftTruncated in the range of principal values of the inverse trigonometric function [ - π, π]And thus is discontinuous. To obtain three of the objectThe dimension distribution, the truncated phases must be restored to a continuous phase distribution, and then the object's profile is reconstructed from the unwrapped phases according to the system structure.

To further understand the phase profilometry, the phase profilometry is described below by way of example.

As shown in fig. 2, the PMP system consists of three major parts, projection, imaging, data acquisition and processing.

The measurement process comprises the following steps: the white light emitted by the laser is projected on a reference plane and the surface of an object to be measured through the sinusoidal grating to respectively obtain the light intensity information of a sinusoidal grating fringe pattern and the light intensity information of a deformed fringe modulated by the surface shape of the object surface, a high-precision CCD camera is adopted to collect fringe images before and after deformation, the received light intensity signals are converted into electric signals and sent to an image card for electric signal amplification, the electric signals are converted into digital images through A/D conversion, the digital images are stored in a system memory of a computer, the computer carries out operation on the digital images, the required phase information is finally obtained by combining a phase technology, and after data processing, the three-dimensional profile image of the surface of the object to be measured can be observed on a display screen of the computer.

In the measurement process of PMP, a reference plane and an image of an object to be measured need to be collected. In general, 2D images are acquired by various cameras. However, when the grating is projected on the surface of an object, the phase of the periodic grating is modulated to generate distortion fringes due to the change of geometrical shapes such as concave-convex shapes of the object, and the like, and the distortion fringe image is a 2D image but carries 3D information, and the information is contained in the phase. The deformed fringe pattern can be thought of as a result of phase and amplitude modulation of the three-dimensional object surface on the projected grating image, which can be characterized by a phase distribution. The method of achieving the acquisition height by extracting the phase is called a phase method. The phase profilometry uses sinusoidal fringe projection, and when a sinusoidal fringe pattern is projected onto a reference plane and onto the surface of a three-dimensional diffuse object, the light intensity of the acquired deformed fringe pattern can be expressed as:

the first condition for obtaining the deformed fringes is that the projection system and the detection system are at an angle. The phase profilometry is still based on triangulation principles. In FIG. 3, R is a reference plane, P₁And P₂Are the entrance and exit pupils of the grating projection system. I is₂And I₁Is the entrance and exit pupils of the CCD imaging system. The imaging optical axis is perpendicular to the reference plane and intersects the projection optical axis at a point O on the reference plane.

When a grating with a parallel fringe and a direction parallel to the Y-axis is projected obliquely onto a reference plane R perpendicular to the Z-axis with a projection apparatus with very small aberration, the fringes of the image on R remain parallel, as shown in fig. 4 (a). Due to the oblique projection, when the stripe image on R is viewed in the vertical direction, the stripes thereon are parallel. When projected with sinusoidal fringes, the intensity of light on a line with the same Y value on the plane varies approximately sinusoidally with a period P, and any point on the line has a corresponding phase valueIf the stripes are directed not on a plane but on a non-flat object surface with a certain height difference from the reference plane R, the stripes are curved when viewed in the vertical direction, although they are still parallel when viewed in the projection direction. As shown in fig. 4(b), the degree of curvature of the striations is related to the height difference of the surface relative to the reference plane R. At this time, the light intensity on the straight line having the same Y value on the plane is no longer a sinusoidal variation with the same period, and there are some regions having a high frequency and some regions having a low frequency. At this time, the phase value of each pointAs opposed to planar. As shown in FIG. 3, the ray originally projected to point A on the reference plane only illuminates point D due to the existence of the measured curved surface, so that the phase of point D measured by the camera is practically the same as the phase of point C on the reference planeThat is, the phase is modulated by the height of the curved surface, which is equivalent to shifting the A point to the C point by the phase shift valueThat is, the sinusoidal fringes are curved into deformed fringes.

A PMP system employing divergent illumination is shown in fig. 5. The height value of the corresponding point on the object surface can be calculated by using the phase value after the imaging surface is unwrapped by any point through the triangular relation shown in fig. 5. Let the fringe period (pitch) on the reference plane be P, the distance from the camera's optical center to the reference plane be l, and its optical axis be perpendicular to the reference plane. Connecting line P between optical center of projection system and optical center of camera device₂I₂Is d and is parallel to the reference plane. D is any point on the object to be measured, and the length h of the line segment DB is the height of the point D. A. And the points C are respectively the intersection points of the connecting line of the point D and the two optical centers and the reference plane.

Since the projection light is divergent, the phase distribution on the reference plane is not linear, and a phase mapping algorithm is required to deal with the calculation from phase to height. When the sinusoidal fringes are projected onto the reference plane, the intensity distribution in the x-direction on the reference plane is:

but the phase value of each point on the reference plane relative to the reference point O is unique and monotonically varying. According to the system structure parameters, the phase distribution on the reference plane light field can be calculated, and the reference plane coordinates (x, y) and the phase distribution are establishedThe mapping relation between the two is equivalent to building a space phase lookup table, and the mapping relation is stored in a computer in the form of a data table. In measuring the surface of a three-dimensional object, D on a detector array_CThe point can measure the phase of an object point DIt corresponds to the phase of point A on the reference planeOn the other hand, the phase position of the same point DC on the reference plane on the array corresponds toHas been stored in the computer in the form of a mapping table, which means that the distance OC is known. The determination of the position A on the reference plane may first be found in a mapping tableTwo closest phase valuesAndmake itThen obtaining by means of linear interpolationThis indicates that OA can be found by measuring and mapping the phase, so:

OC＝OC-OA (4)

by a similar triangle Δ P₂DI₂And Δ ADC can calculate the height distribution of the object points as:

in practical application, AC is less than or equal to d, and the above formula can be further simplified as follows:

the process of reconstructing the three-dimensional contour image specifically comprises the following steps:

s101, conducting sine stripe scanning on the object to be detected.

S102, respectively obtaining a reference fringe pattern of the reference plane and a deformation fringe pattern of the object to be detected.

The phase of the periodic fringes is modulated due to the fact that the bending of the fringes is caused by the height variation of the curved surface of the object. That is, the degree of curvature of the fringes is related to the height difference of the surface of the object to be measured relative to the reference plane, and the phase change caused by the modulation of the object to be measured can be obtained according to the geometric trigonometric relation.

S103, carrying out spatial phase calibration on the reference plane, and establishing a spatial phase lookup table according to the spatial phase calibration.

And S104, performing phase shift processing on the deformed stripes on the object to be detected to obtain a plurality of phase shift graphs.

In this embodiment, the laser is moved back and forth to move the sinusoidal stripes projected onto the object surface by 0, 2, and 4 pixels along the x-axis direction, thereby generating 3 light intensity distributions I₁，I₂，I₃As shown in fig. 6.

S105, a truncated phase distribution is calculated from the plurality of phase shift maps, as shown in fig. 7 (a).

And S106, obtaining continuous phases according to the truncated phase distribution.

Specifically, the truncated phase distribution is restored to the original continuous phase distribution by phase unwrapping. In this embodiment, the truncated phase distribution is subjected to phase unwrapping processing by a wrapper function unwrap in MATLAB software, so as to obtain a continuous phase, and the result is shown in fig. 7 (b).

And S107, obtaining the phase of the object to be measured according to the continuous phase.

Continuous phase by phase unwrappingWherein, the phase value of the object to be measured is includedAlso included are phase values of the reference planeNamely, it isTo obtain a phase value of an object to be measuredMust be selected fromMinusIn this embodiment, the search is performed by a space phase lookup tableTwo closest phase valuesAndmake itThen obtaining by means of linear interpolationThe phase of the object to be measured is:

and S108, acquiring the height information of the object to be measured according to the phase of the object to be measured.

In this example, it is obtained according to the height formula (6):

and obtaining the height information of the reconstructed object to be measured by calculating a plurality of phase shift graphs. In this embodiment, d and l are parameters preset by the system, and a function mesh in MATLAB software is used to output a three-dimensional profile of the object to be measured.

The spatial phase calibration in the above embodiment is based on a cartesian coordinate system (XYZ coordinate system), and it can be understood that in an alternative embodiment, the spatial phase calibration may also be based on a polar coordinate system (360 degrees).

In view of the above description of the laser interference device and the three-dimensional reconstruction imaging system using the same provided by the present invention, those skilled in the art will appreciate that there are variations in the embodiments and applications of the laser interference device according to the concepts of the present invention.