阅读说明：本技术 一种高效能mems激光雷达接收系统 (High-performance MEMS laser radar receiving system ) 是由 张艳妮 郑文会 夏长锋 范乔丹 于 2020-11-27 设计创作，主要内容包括：本发明属于激光雷达技术领域,具体涉及一种高效能MEMS激光雷达接收系统。解决由于MEMS微振镜尺寸小,导致MEMS激光雷达测距能力不够的问题,包括异型聚光镜、MEMS微振镜、准直透镜、后聚光透镜以及光电探测器；异型聚光镜与MEMS微振镜的中心处于同一直线上,且光轴呈一定的角度；MEMS微振镜、准直透镜、后聚光透镜、光学探测器的中心处于同一直线上,且同光轴设置；异型聚光镜用于将经目标反射的大面积反射光束在子午和/或弧矢方向聚焦；MEMS微振镜用于将异型聚光镜聚焦后的线光束或点阵光束反射至准直透镜；准直透镜用于将MEMS微振镜的反射光束在子午和弧矢方向的至少一个方向上进行光束准直；后聚光透镜用于将准直透镜准直后的平行光束会聚在光电探测器。(The invention belongs to the technical field of laser radars, and particularly relates to a high-efficiency MEMS laser radar receiving system. The problem that the MEMS laser radar has insufficient range finding capability due to the small size of the MEMS micro-vibration mirror is solved, and the MEMS laser radar comprises a special-shaped collecting mirror, an MEMS micro-vibration mirror, a collimating lens, a rear collecting lens and a photoelectric detector; the centers of the special-shaped condenser and the MEMS micro-vibration mirror are positioned on the same straight line, and the optical axes form a certain angle; the centers of the MEMS micro-vibration mirror, the collimating lens, the rear condensing lens and the optical detector are positioned on the same straight line and are arranged on the same optical axis; the special-shaped condenser is used for focusing a large-area reflected light beam reflected by a target in the meridian and/or sagittal directions; the MEMS micro-vibration mirror is used for reflecting the line beam or the dot matrix beam focused by the special-shaped condenser lens to the collimating lens; the collimating lens is used for collimating the reflected light beam of the MEMS micro-vibrating mirror in at least one of the meridional and sagittal directions; the rear condenser lens is used for converging the parallel light beams collimated by the collimating lens on the photoelectric detector.)

1. A high-performance MEMS laser radar receiving system is characterized in that: the micro-vibration micro-mirror system comprises a special-shaped collecting lens (1), an MEMS micro-vibration lens (2), a collimating lens (3), a rear collecting lens (4) and a photoelectric detector (5) which are arranged in a receiving light path in sequence; the centers of the special-shaped condenser (1) and the MEMS micro-vibration mirror (2) are positioned on the same straight line, and the optical axis forms a certain angle; the centers of the MEMS micro-vibration mirror (2), the collimating lens (3), the rear condensing lens (4) and the optical detector (5) are positioned on the same straight line and are arranged on the same optical axis;

the special-shaped condenser lens (1) is used for focusing a large-area reflected light beam reflected by a target in the meridian and/or sagittal directions to form a line beam or a dot matrix beam;

the MEMS micro-vibration mirror (2) is used for reflecting the line beam or the dot beam focused by the special-shaped condenser (1) to the collimating lens (3);

the collimating lens (3) is used for collimating the reflected light beam of the MEMS micro-vibrating mirror (2) in at least one of the meridional and sagittal directions to form a parallel light beam;

the rear condenser lens (4) is used for converging the parallel light beams collimated by the collimator lens (3) on the photoelectric detector (5).

2. The high performance MEMS lidar receiving system of claim 1, wherein: the special-shaped condenser lens (1) is an arc condenser lens, and large-area reflected light beams reflected by a target are focused in the meridian direction and translated in the sagittal direction to form line beams.

3. The high performance MEMS lidar receiving system of claim 2, wherein: the collimating lens (3) is a cylindrical lens, collimates the reflected light beam passing through the MEMS micro-vibration mirror (2) in the meridian direction and does not change the transmission of the light beam in the sagittal direction.

4. The high performance MEMS lidar receiving system of any of claims 1-3, wherein: the front curvature radius R of the arc-shaped condensing lens₁Rear radius of curvature R₂Satisfies the following conditions:

wherein l' is the distance between the arc-shaped condenser lens and the MEMS micro-vibrating mirror (2), f is the focal length of the arc-shaped condenser lens, and n is the refractive index of the arc-shaped condenser lens.

5. The high performance MEMS lidar receiving system of claim 4, wherein: the arc scanning angle theta of the arc-shaped condensing lens is 2 beta, wherein beta is a mechanical rotation angle of the MEMS micro-galvanometer (2).

6. The high performance MEMS lidar receiving system of claim 5, wherein: the special-shaped condenser lens (1) is formed by splicing a single arc-shaped condenser lens or a plurality of arc-shaped condenser lenses.

7. The high performance MEMS lidar receiving system of claim 5, wherein: the rear condenser lens (4) is a single-chip aspheric lens, is fixed in the mounting sleeve and is matched with the optical detector (5) through a base.

8. The high performance MEMS lidar receiving system of claim 7, wherein: the included angle between the optical axes of the special-shaped condenser (1) and the MEMS micro-vibration mirror (2) is any angle between 30 and 60 degrees.

9. The high performance MEMS lidar receiving system of claim 1, wherein: the special-shaped condenser lens (1) is an arc condenser lens with a surface on which N micro-focusing optical structures are arranged, large-area reflected light beams reflected by a target are focused simultaneously in the meridian and sagittal directions to form dot matrix light beams, wherein N is a positive integer greater than or equal to 2.

10. The high performance MEMS lidar receiving system of claim 9, wherein: the collimating lens (3) is a spherical or aspheric circular lens, and collimates the reflected light beam passing through the MEMS micro-vibration mirror (2) to form a parallel light beam.

11. The high performance MEMS lidar receiving system of claim 10, wherein: the micro-focusing optical structure is a micro-condensing lens, and N micro-condensing lenses are uniformly distributed on the arc-shaped curved surface substrate to form the arc-shaped condensing lens.

12. The high performance MEMS lidar receiving system of any of claims 9-11, wherein: the front surface of the micro condenser lens is a spherical surface or an aspheric surface, and the focal length l of the spherical surface or the aspheric surface micro condenser lens₁，l₂......l_NSatisfies the following conditions:

wherein R is the radius of the arc-shaped curved surface substrate, and theta is the included angle of the ith micro-focusing lens and the axis of the arc-shaped curved surface substrate; l₁The focal length of the first micro-focusing lens is set, the optical axis of the first micro-focusing lens is coincident with the optical axis of the arc-shaped curved surface substrate, and i is a positive integer from 2 to N;

front curvature radius R of each micro condenser lens₁Rear radius of curvature R₂Satisfies the following conditions:

n' is a refractive index of each micro condenser lens, and j is a positive integer of 1 to N.

13. The high performance MEMS lidar receiving system of claim 12, wherein: the arc scanning angle theta of the arc-shaped condenser lens is 2 beta, wherein beta is the mechanical rotation angle of the MEMS micro-galvanometer (2).

Technical Field

The invention belongs to the technical field of laser radars, and particularly relates to an MEMS laser radar receiving system.

Background

The laser radar transmits laser beams to a target area, receives the laser beams reflected by the target area, and acquires relevant information such as distance, speed, direction and the like of a detection target according to the flight time of the transmitted and received laser beams. The method has the advantages of high spatial resolution, high sensitivity, strong anti-interference capability, small volume, light weight and the like, and is rapidly developed in the fields of accurate guidance, target identification and the like.

MEMS lidar is a laser detection and ranging system that employs MEMS micro-mirrors to manipulate a beam at microscopic dimensions. The core device is MEMS micro-vibrating mirror. The MEMS micro-vibrating mirror is a micro-electromechanical system integrating optical, electronic and mechanical technologies. The MEMS micro-vibrating mirror has the advantages of small size, low energy consumption, high response speed, high integration level and the like, but the effective mirror surface size of the MEMS micro-vibrating mirror is small, the size of a received reflected light beam is limited, the range finding capability of the MEMS laser radar is greatly reduced, and the application range of the MEMS laser radar is limited. In order to solve this problem, the conventional treatment methods include: adding a large-size beam expander, such as Chinese patent CN110275177A, solid-state laser radar, structure and control method thereof; the solution is to add a mirror array, such as chinese patent CN210690806U, "laser radar receiving system", or increase the number of MEMS micro-vibrating mirrors. However, the current treatment method has the following problems: firstly, the number of hardware devices (MEMS micro-vibrating mirrors or reflectors) is increased, so that the cost is greatly increased, the difficulty in debugging the light path is high, and the wide popularization of laser radars is not utilized. Secondly, the addition of a large-size beam expander complicates the optical system and has limited beam expanding capability (generally no more than 3 times). Based on the above problems, it is necessary to provide a new high-performance MEMS lidar optical receiving system.

Disclosure of Invention

The invention provides a high-efficiency MEMS laser radar receiving system, aiming at solving the problem of insufficient range finding capability of an MEMS laser radar due to small size of an MEMS micro-vibration mirror and overcoming the limitation of a scheme of increasing the area of a received light beam of a traditional MEMS laser radar. The method has profound significance for further expanding the application range of the MEMS laser radar.

The technical scheme of the invention provides a high-efficiency MEMS laser radar receiving system, which is characterized in that: the micro-vibration micro-mirror system comprises a special-shaped collecting lens, an MEMS micro-vibration lens, a collimating lens, a rear collecting lens and a photoelectric detector which are sequentially arranged in a receiving light path; the centers of the special-shaped condenser and the MEMS micro-vibration mirror are positioned on the same straight line, and the optical axes form a certain angle; the centers of the MEMS micro-vibration mirror, the collimating lens, the rear condensing lens and the optical detector are positioned on the same straight line and are arranged on the same optical axis;

the special-shaped condenser is used for focusing a large-area reflected light beam reflected by a target in the meridian and/or sagittal directions to form a line beam or a dot matrix beam;

the MEMS micro-vibration mirror is used for reflecting the line beam or the dot matrix beam focused by the special-shaped condenser to the collimating lens;

the collimating lens is used for collimating the reflected light beam of the MEMS micro-vibrating mirror in at least one of the meridional and sagittal directions to form a parallel light beam;

the rear condenser lens is used for converging the parallel light beams collimated by the collimating lens on the photoelectric detector.

Furthermore, in order to focus the large-area reflected light beam reflected by the target in the meridional direction, the special-shaped condenser lens is an arc-shaped condenser lens, and the large-area reflected light beam reflected by the target is focused in the meridional direction and translated in the sagittal direction to form a line light beam.

Further, the collimating lens is a cylindrical lens, and collimates the reflected light beam passing through the MEMS micro-vibrating mirror in the meridional direction without changing the propagation of the light beam in the sagittal direction.

Further, the front curvature radius R of the arc-shaped condenser lens₁Rear radius of curvature R₂Satisfies the following conditions:

wherein l' is the distance between the arc-shaped condensing lens and the MEMS micro-vibrating mirror, f is the focal length of the arc-shaped condensing lens, and n is the refractive index of the arc-shaped condensing lens.

Further, in order to increase the receiving area of the reflected light beam in the full scanning field range, the arc-shaped scanning angle θ of the arc-shaped condenser lens is 2 β, where β is the mechanical rotation angle of the MEMS micro-galvanometer.

Furthermore, in order to realize the receiving of larger reflected light beams and the detection of longer distance of the laser radar, the special-shaped condenser lens is formed by splicing a single arc-shaped condenser lens or a plurality of arc-shaped condenser lenses.

Further, in order to effectively converge the reflected light beam, reduce the number of optical condenser lenses and improve the energy efficiency of the whole MEMS receiving system, the rear condenser lens is a single-chip aspheric lens, is fixed in the mounting sleeve and is matched with the optical detector through a base.

Furthermore, in order to enable the reflected light beams after the special-shaped condensation to be efficiently received by the photoelectric detector through the rear condenser lens in the full scanning range, the included angle between the special-shaped condenser lens and the optical axis of the MEMS micro-vibrating mirror is any angle between 30 and 60 degrees.

Furthermore, in order to focus the large-area reflected light beam reflected by the target in the meridian and sagittal directions at the same time, the special-shaped condenser lens is an arc condenser lens with one surface type provided with N micro-focusing optical structures, and the large-area reflected light beam reflected by the target is focused in the meridian and sagittal directions at the same time to form a lattice light beam, wherein N is a positive integer greater than or equal to 2.

Furthermore, the collimating lens is a spherical or aspherical circular lens, and collimates the reflected light beam passing through the MEMS micro-vibrating mirror to form a parallel light beam.

Furthermore, in order to more efficiently receive large-area reflected light beams in the meridian and sagittal directions, the micro-focusing optical structure is a micro-condensing lens, and the N micro-condensing lenses are uniformly distributed on the arc-shaped curved substrate to form the arc-shaped condensing lens.

Furthermore, in order to facilitate lens processing and improve the light-gathering capability of the micro-focusing optical structure, the front surface of the micro-light-gathering lens is a spherical surface or an aspheric surface, and the focal length l of the spherical or aspheric micro-light-gathering lens₁，l₂......l_NSatisfies the following conditions:

wherein R is the radius of the arc-shaped curved surface substrate, and theta is the included angle of the ith micro-focusing lens and the axis of the arc-shaped curved surface substrate; l₁The focal length of the first micro-focusing lens can be obtained according to the distance between the first micro-focusing lens and the MEMS galvanometer, the optical axis of the first micro-focusing lens is superposed with the optical axis of the arc-shaped curved surface substrate, and i is a positive integer from 2 to N;

front curvature radius R of each micro condenser lens₁Rear radius of curvature R₂Satisfies the following conditions:

n' is a refractive index of each micro condenser lens, and j is a positive integer of 1 to N.

Further, in order to increase the receiving area of the echo light beam in the full scanning field range, the arc scanning angle θ of the arc condenser lens is 2 β, where β is the mechanical rotation angle of the MEMS micro-galvanometer.

The invention has the beneficial effects that:

1. the MEMS laser radar receiving system comprises a special-shaped light condensing device, wherein the special-shaped light condensing device is a special-shaped light condensing lens. The special-shaped condensing lens focuses in the meridian direction (including the target point and the direction of the received light beam of the optical axis) and/or the sagittal direction (including the optical axis and the direction of the received light beam vertical to the meridian direction) to form a line light beam or a dot matrix light beam; in one or more directions of meridian and sagittal, the special-shaped condenser lens can converge a large-area reflected light beam, and when the size of the special-shaped condenser lens is more than or equal to 16mm, the single-chip receiving efficiency is more than 6 times of that of the single MEMS micro-vibrating mirror (the data is based on the following laser radar distance formula,obtained), is far higher than that of the prior artThe reception efficiency of the scheme. The special-shaped condensing lens is matched with the MEMS micro-vibrating mirror to scan in the sagittal direction and/or the meridional direction, so that the MEMS laser radar can receive reflected beams with the same area under different scanning angles, and the MEMS laser radar can receive the reflected beams with high efficiency in the whole scanning range. Compared with the conventional processing method, the special-shaped condensing lens has the advantages of simple structure, low cost and simple debugging. The method can converge the echo beams in one and/or a plurality of directions, and compared with a single MEMS galvanometer, the method increases the receiving area of the echo beams, improves the receiving efficiency of the MEMS laser radar, and has profound significance for low-cost popularization and long-distance and high-efficiency detection of the laser radar.

2. The special-shaped condensing lens can be an arc-shaped condensing lens, the curvature of the arc-shaped condensing lens in one direction of the meridian direction or the sagittal direction can be 0, light rays are transmitted in the direction, the special-shaped condensing lens is equivalent to a parallel flat plate, and the light rays only translate. With some curvature in the other direction. The light rays are transmitted in the direction, the special-shaped condensing lens is equivalent to a positive lens, and the light rays are converged. The MEMS micro-galvanometer is matched under different scanning angles, the meridional direction can receive light beams with the same area, and the sagittal direction does not change the receiving area of the MEMS galvanometer, so that the receiving efficiency of the MEMS laser radar in the whole scanning field range is improved. The arc-shaped condensing lens has a simple structure, is easy to process, and can be designed by a single sheet or multiple sheets.

3. The special-shaped condensing lens can also be an arc-shaped condensing lens with N micro-focusing optical structures on the surface, can simultaneously converge the reflected light beams in the meridian direction and the sagittal direction, focuses the incident reflected light beams into N convergence points to enter the MEMS micro-vibrating mirror, simultaneously enlarges the receiving areas of the reflected light beams in the meridian direction and the sagittal direction, and improves the detection capability of the MEMS laser radar.

Drawings

FIG. 1 is a schematic diagram of a high performance MEMS lidar receiving system.

Fig. 2 is a schematic optical path diagram of a high-performance MEMS lidar receiving system, in which a is a sagittal (meridional) receiving diagram, and b is a meridional (sagittal) receiving diagram.

Fig. 3 is a high performance MEMS lidar receiving system according to the first embodiment, in which a is a meridional receiving diagram and b is a sagittal receiving diagram.

In the figure, 1-special-shaped condenser, 2-MEMS micro-vibrating mirror, 3-collimating lens, 4-rear condenser lens and 5-photoelectric detector.

Fig. 4 is a schematic diagram of the expanded received energy of the special-shaped condenser.

Fig. 5 is a special-shaped (arc-shaped) condenser.

Fig. 6 shows a high performance MEMS lidar receiving system according to a second embodiment.

In the figure, 1-special-shaped condenser, 2-MEMS micro-vibrating mirror, 3-collimating lens, 4-rear condenser lens and 5-photoelectric detector.

Fig. 7 shows a micro-focusing profile condenser lens.

Fig. 8 is a schematic diagram of a micro-focusing special-shaped condenser lens.

FIG. 9 is a schematic cross-sectional view of a micro-focusing special-shaped condenser lens.

In the figure, 01-a first micro condenser lens, 02-a second micro condenser lens, 03-a third micro condenser lens, 04-a fourth micro condenser lens, 05-a fifth micro condenser lens, 06-a sixth micro condenser lens, and 07-a focus of the first micro condenser lens.

Detailed Description

The invention is further described with reference to the following figures and specific embodiments.

As shown in fig. 1 and fig. 2, the high-performance MEMS lidar receiving system of the present invention includes a special-shaped light-gathering device, an MEMS micro-vibrating mirror, a collimating device, and a receiving device, which are sequentially disposed. The special-shaped light gathering device is used for focusing a large-area reflected light beam reflected by a target in the meridian and/or sagittal directions to form a line beam or a dot matrix beam, and optical plastics such as PMMA (polymethyl methacrylate), COC (chip on glass) and the like, optical glass and other optical materials which are easy to form are usually selected. The MEMS micro-vibration mirror has a certain mechanical rotation angle, and the MEMS micro-vibration mirror is controlled by the MEMS micro-vibration mirror driving circuit to swing angularly to form a laser scanning surface. The collimating device is a collimating lens and can converge light beams at least in any one of the meridional direction or the sagittal direction. May be one or more cylindrical, spherical or aspherical lenses. The optical receiving device comprises a rear converging lens group and an optical detector. The rear converging lens group is a single-chip or multi-chip spherical or aspheric lens and can converge light rays into the optical detector. The optical detector may be: APD (avalanche photo diode), photomultiplier tube and the like. The laser emits laser to detect a target, and laser beams reflected by the target are focused in one or more directions of the special-shaped light condensing device and focused into linear beams or dot matrix beams to enter the MEMS micro-vibrating mirror. The collimated light beam enters a collimating device after being reflected by the MEMS micro-vibration mirror, and the collimating device collimates the light beam in at least one direction of a meridian direction and a sagittal direction to form a parallel light beam. The parallel light beams are finally converged on an optical detector of the optical receiving device through a rear collimating lens group of the optical receiving device.

Example one

As shown in fig. 3, the MEMS lidar receiving system of this embodiment includes a special-shaped condenser lens 1, an MEMS micro-resonator 2, a collimator lens 3, a rear condenser lens 4, and a photodetector 5. The centers of the special-shaped condenser 1 and the MEMS micro-vibration mirror 2 are positioned on the same horizontal line, and the optical axis of the special-shaped condenser and the MEMS micro-vibration mirror 2 form a certain angle which is the initial angle of the MEMS micro-vibration mirror 2. This angle may be any angle of 30-60 degrees. The centers of the MEMS micro-vibrating mirror 2, the collimating lens 3, the rear condensing lens 4 and the optical detector 5 are positioned on the same straight line.

The special-shaped condenser lens 1 is an arc condenser lens, and can converge a reflected light beam in the meridian direction and translate the reflected light beam in the sagittal direction to form a linear laser beam entering the MEMS micro-vibration lens 2.

The large-area reflected light beams are converged to the MEMS micro-vibration mirror 2 by the special-shaped condenser lens 1 in the meridian direction, so that the receiving area of the MEMS micro-vibration mirror 2 in the meridian direction is increased, and the detection capability of the MEMS laser radar is improved. The reflected light beam is translated by the special-shaped condenser 1 in the sagittal direction to enter the MEMS micro-vibrating mirror 2, so that the receiving area of the MEMS micro-vibrating mirror 2 is not changed in the sagittal direction.

The special-shaped collecting mirror 1 is designed in an arc shape, the meridian direction can receive light beams with the same area by matching with the MEMS micro-vibration mirror 2 under different scanning angles, and the sagittal direction does not change the receiving area of the MEMS vibration mirror, so that the receiving efficiency of the MEMS laser radar in the whole scanning field range is improved.

The collimating lens 3 is a cylindrical lens, and can collimate the light beam reflected by the MEMS micro-galvanometer 2 in the meridional direction without changing the propagation of the light beam in the sagittal direction. The rear condenser lens 4 is a single-chip aspheric lens, and the rear condenser lens 4 is fixed in the mounting sleeve and matched with the optical detector 5 through a base. The optical detector 5 may be, but is not limited to, an APD (avalanche photo diode), and may also be other optical receiving devices such as a photomultiplier tube.

Laser beams emitted by the laser are reflected by a target and then enter the special-shaped condenser lens 1, and are converged by the special-shaped condenser lens 1 to form a linear beam which enters an optical area of the MEMS micro-vibration mirror 2. And then the light beam is reflected by the MEMS micro-oscillator and then enters the collimating lens 3 to form a parallel light beam. The parallel light beams are incident on the rear condenser lens 4 and secondarily condensed on the optical detector 5.

According to a laser radar detection range equation:

in the formula: p_sThe power of an echo signal received by the laser radar; p_iThe peak power of the laser pulse emitted by the laser radar; s is the effective receiving area of the laser radar; r is the distance between the target and the laser radar; eta_sysIs a laser radar system parameter; eta_atmThe influence factor of the signal in the atmospheric transmission process is shown; according to the formula, when the test is carried out in the same environment, the echo energy of the laser radar is only related to the effective receiving area S of the laser radar and the distance R between the target and the laser radar, and other influence factors can be regarded as a fixed value, so that the radar transmission equation can be simplified as follows:

under the same detection distance R, the area of the MEMS micro-vibrating mirror 2 for receiving the light beam is assumed to be S₁The beam receiving area of the special-shaped condenser 1 is S₂. The receiving power P of the MEMS laser radar containing the special-shaped condenser₂MEMS laser radar receiving power P of single micro-vibration mirror₁The ratio of (A) to (B) is:

therefore, the receiving optical area can be changed by adjusting the structural size (length and width) of the special-shaped condenser lens 1 according to the requirement and the actual situation, so that the receiving power of the MEMS laser radar is improved, and the corresponding schematic diagram is shown in fig. 4.

For example, the following steps are carried out: the diameter of the optical effective surface of the single MEMS micro-vibration mirror is 3mm, the height of the meridian plane of the special-shaped collecting mirror is 16mm, and the width of the sagittal plane is 3mm which is the receivable width of the MEMS micro-vibration mirror. For the receiving targets at the same distance, the received power ratio is:

namely: when the height of the noon surface is 16mm, the receivable energy is 6.8 times of the energy received by the single micro-vibrating mirror MEMS laser radar.

In addition, the scanning angle theta of the MEMS laser radar and the mechanical rotation angle beta of the MEMS micro-vibrating mirror 2 have the following relationship:

θ＝2β

the MEMS micro-galvanometer 2 mentioned in the invention can be a one-dimensional or two-dimensional MEMS micro-galvanometer, and the scanning range can be in any range of 30-360 degrees according to the rotation angle of the MEMS micro-galvanometer.

The positions of all the optical devices are not limited to the above-mentioned ones, nor are the magnitudes of the deflections and angles of the positions limited to the described magnitudes.

FIG. 5 shows a special-shaped arc-shaped condenser lens, the main optical parameter is the front curvature radius R₁Rear radius of curvature R₂Width L and arc scan angle θ. Front radius of curvature R₁And a rear radius of curvature R₂Can be determined according to the formula:

derived (from a gaussian variant). Wherein l' is the distance between the special-shaped condenser and the MEMS galvanometer. f is the focal length of the special-shaped condenser. n is the refractive index of the special-shaped condenser and the value range is 1.4-1.9. The width L is the first receiving surface of the laser radar, and the distance formula of the laser radar can show that the larger the value L is, the more the returned reflected light beams are, and the stronger the obtained signal is. According to the requirements of different receiving efficiencies, the structural parameters of the anisotropic light-gathering device, such as surface curvature, length, width and the like, can be modified.

Example two

Fig. 6 shows a high performance MEMS lidar receiving system according to this embodiment. The receiving system comprises a special-shaped condenser lens 1, an MEMS micro-vibration lens 2, a collimating lens 3, a rear condenser lens 4 and an optical detector 5.

The centers of the special-shaped condenser 1 and the MEMS micro-vibration mirror 2 are positioned on the same horizontal line, and the optical axis of the special-shaped condenser and the MEMS micro-vibration mirror form a certain angle which is the initial angle of the MEMS. This angle may be any angle of 30-60 degrees. The centers of the MEMS micro-vibrating mirror 2, the collimating lens 3, the rear condensing lens 4 and the photoelectric detector 5 are positioned on the same straight line. The special-shaped condenser lens 1 is an arc condenser lens with N micro-focusing optical structures on one surface, can converge reflected light beams in the meridian direction and the sagittal direction at the same time, focuses the incident reflected light beams into N convergence points to enter the MEMS micro-vibration lens 2, enlarges the receiving areas of the reflected light beams in the meridian direction and the sagittal direction, and improves the detection capability of the MEMS laser radar. The special-shaped condensing lens 1 is designed in an arc shape, and is matched with different scanning angles of the MEMS micro-vibration lens to instantaneously receive light beams with the same area in the meridian and sagittal directions, so that the receiving efficiency of the MEMS laser radar in the whole scanning field range is improved. The collimating lens 3 is a spherical or aspherical circular lens, and can collimate the light beam reflected by the MEMS micro-vibrating mirror 2 to form a parallel light beam. The parallel light beam is incident on the rear condenser lens 4 and is finally focused on the optical detector 5. The rear condenser lens 4 is a single-chip aspherical lens. The rear condenser lens 4 is fixed in the mounting sleeve and is matched with the optical detector 5 through a base. For the optical detector 5, APD (avalanche photodiode) can be, but not limited to. Laser beams emitted by the laser are reflected by a target and then enter the special-shaped condensing lens 1, and are converged by the special-shaped condensing lens 1 to form N focusing points to enter an optical area of the MEMS micro-vibration mirror. And then reflected into the collimator lens 3 to form a parallel beam. The parallel light beams are incident on the rear condenser lens 4 and secondarily condensed to the optical detector 5.

Fig. 7 shows an arc-shaped condensing lens having N micro-focusing optical structures on a surface, where the micro-focusing optical structures refer to the micro-condensing lenses, and the N micro-condensing lenses are uniformly arranged on an arc-shaped curved substrate. The front surface of the micro condenser lens may be spherical, aspherical, or the like.

As shown in FIG. 9, the focal length l of the spherical and aspherical micro condenser lens₁，l₂......l_NSatisfies the following conditions:

wherein R is the radius of the arc-shaped curved surface substrate, and theta is the included angle of the ith micro-focusing lens and the axis of the arc-shaped curved surface substrate; l₁The focal length of the first micro-focusing lens 01 is shown, the optical axis of the first micro-focusing lens 01 is superposed with the optical axis of the arc-shaped curved surface substrate, and i is a positive integer from 2 to N;

the focal length l of the micro focusing lens 1, 2₁，l₂，l₃，l₄......l_N. Front curvature radius R of each micro condenser lens₁Rear radius of curvature R₂Satisfies the following conditions:

n' is a refractive index of each micro condenser lens, and j is a positive integer of 1 to N.

The N micro condenser lenses divide the field of view into N parts. Each microlens constitutes an energy channel. The micro condenser lens array respectively receives meridional and sagittal reflected light beams of each micro field, so that the reflected light beams are received within a receiving angle. Radius of curvature R of each micro condenser lens₁、R₂And the focal length may be different or the same. The focal length value of each micro focusing lens is reduced along with the increase of the distance between the micro focusing lens and the axis of the curved substrate, so that the reflected light beams can be converged on the MEMS vibrating mirror through the micro focusing special-shaped collecting lens.

Fig. 8 is a schematic diagram of a microstructure profile condenser lens. Where S1 is the single MEMS micro-mirror 2 receiving area. S2 denotes the receiving area of the microstructure shaped condenser lens 1. It can be seen that S2 is larger than the area of S1. According to the distance formula of the laser radar, the receiving power of the laser radar is S2/S1 times of that of a single MEMS galvanometer. Meanwhile, the front surface of the S2 has certain curvature in the meridional and sagittal directions, so that the echo light beams can be converged. Therefore, the receiving efficiency of the radar can be improved by adjusting the size of the S2 and the curvature radius of the front and rear surfaces.