阅读说明：本技术 一种激光脉冲时间间隔处理方法及激光雷达探测系统 (Laser pulse time interval processing method and laser radar detection system ) 是由 彭志永 高挺挺 谢光辉 穆学桢 雷卫宁 严毅 周树平 刘振力 张宁华 钟如亮 于 2020-12-11 设计创作，主要内容包括：一种激光脉冲时间间隔处理方法及激光雷达探测系统,通过得到的准确激光器驱动信号发出时刻,能够消除由于激光器的响应时间不固定,而引起的激光脉冲测距起始信号随机跳动的问题,并且能够计算出激光脉冲从发射到被测物体之间的飞行时间,最终得到被测物体的准确距离数据。通过二维MOEMS扫描镜组件的光窗的分光功能,能够实现对激光发射脉冲与激光回波脉冲进行分时测量,从而计算出准确的激光脉冲飞行时间；另外,由于本探测系统使用的是单元APD探测器,因此本雷达探测系统具有体积小、质量轻和成本低的优点。(A laser pulse time interval processing method and a laser radar detection system can solve the problem that a laser pulse ranging initial signal is in random jumping caused by unfixed response time of a laser through the obtained accurate laser driving signal sending time, and can calculate the flight time of a laser pulse from emission to an object to be detected, and finally obtain accurate distance data of the object to be detected. Through the light splitting function of the optical window of the two-dimensional MOEMS scanning mirror assembly, the time-sharing measurement of laser emission pulses and laser echo pulses can be realized, so that the accurate laser pulse flight time is calculated; in addition, the detection system uses a unit APD detector, so the radar detection system has the advantages of small volume, light weight and low cost.)

1. A laser pulse time interval processing method is characterized in that:

step 1: laser emitted by a laser radar laser light source is subjected to pulse shaping through a transmitting optical device (1) and is collimated into quasi-parallel laser pulses;

step 2: quasi-parallel laser pulses are reflected to an optical window (3.1) of a two-dimensional MOEMS scanning mirror assembly (3) through a first reflecting mirror (2), a small part of the quasi-parallel laser pulses are reflected to a mirror surface of a second reflecting mirror (4) through the optical window (3.1), and a large part of the quasi-parallel laser pulses are transmitted to the mirror surface of a scanning micro mirror (3.2) after penetrating through the optical window (3.1) of the two-dimensional MOEMS scanning mirror assembly (3);

and step 3: the second reflecting mirror (4) directly reflects the corresponding quasi-parallel laser pulse to a light receiving end of the unit APD detector (6), the unit APD detector (6) converts the quasi-parallel laser pulse into a corresponding electric signal, the electric signal is amplified by the transimpedance amplification circuit (7) to obtain a laser pulse emission signal, the obtained laser pulse emission signal is output to the processor (8), the processor (8) performs AND operation on the signal and a laser driving signal, and the operated signal is used as an initial reference signal of pulse ranging;

and 4, step 4: the scanning micro-mirror (3.2) reflects the corresponding quasi-parallel laser pulse to a measured object (9), the quasi-parallel laser pulse is subjected to diffuse reflection on the surface of the measured object (9), part of the reflected laser beam is received by the receiving optical device (5), then the part of the laser beam is focused and imaged on the APD detector, the unit APD detector (6) converts the reflected laser beam into a corresponding electric signal, the electric signal is amplified by the transimpedance amplification circuit (7) to obtain a laser pulse echo signal, and the laser pulse echo signal is output to the processor (8) as a stop reference signal for pulse ranging;

and 5: the processor (8) can accurately calculate the distance of the measured object (9) according to the starting reference signal, the stopping reference signal and the light velocity of the pulse ranging; and the stop reference signal of the pulse ranging is used as a preparation signal for the next laser pulse emission of the laser radar.

2. The laser pulse interval processing method as claimed in claim 1, wherein the laser radar detection system is used, and is characterized in that: the device comprises a transmitting optical device (1), a first reflecting mirror (2), a two-dimensional MOEMS scanning mirror assembly (3), a second reflecting mirror (4), a receiving optical device (5), a unit APD detector (6), a transimpedance amplification circuit (7) and a processor (8); the light inlet end of the transmitting optical device (1) is correspondingly connected with a laser of a laser radar, and the light outlet end of the transmitting optical device (1) corresponds to the mirror surface of the first reflector (2);

the two-dimensional MOEMS scanning mirror assembly (3) is positioned on the right side of the transmitting optical device (1), a second reflecting mirror (4) is arranged above the two-dimensional MOEMS scanning mirror assembly (3), the two-dimensional MOEMS scanning mirror assembly (3) is used for receiving reflected light of the first reflecting mirror (2), an optical window (3.1) of the two-dimensional MOEMS scanning mirror assembly (3) can reflect a small part of received laser to the mirror surface of the second reflecting mirror (4), and a scanning micro mirror (3.2) in the two-dimensional MOEMS scanning mirror assembly (3) can reflect the received laser to a measured object (9);

the receiving optical device (5) is located on the right side of the two-dimensional MOEMS scanning mirror assembly (3), a measured object (9) is arranged above the receiving optical device (5), a unit APD detector (6) is arranged below the receiving optical device (5), the unit APD detector (6) can receive reflected light of the second reflecting mirror (4), and a signal output end of the unit APD detector (6) is correspondingly and electrically connected with the processor (8) through a transimpedance amplifying circuit.

3. The laser pulse interval processing method as claimed in claim 2, wherein: the two-dimensional MOEMS scanning mirror assembly (3) is of a right-angle trapezoidal structure, wherein the inclined edge is an optical window (3.1), a scanning micro mirror (3.2) is arranged in the assembly, and the scanning micro mirror (3.2) is arranged on the inner bottom surface corresponding to the optical window (3.1).

4. The laser pulse interval processing method as claimed in claim 2, wherein: the optical window (3.1) is plated with an antireflection film corresponding to the wavelength of the laser light source.

5. The laser pulse interval processing method as claimed in claim 2, wherein: the longitudinal distance between the center of the first reflecting mirror (2) and the center of an optical window (3.1) of the two-dimensional MOEMS scanning mirror assembly (3) is H1, the transverse distance between the center of the first reflecting mirror and the center of the optical window is L1, and the inclination angle theta 1 of the first reflecting mirror (2) relative to the reference axis x is as follows:

6. the laser pulse interval processing method as claimed in claim 5, wherein: the corresponding included angle between the optical window (3.1) and the inner bottom surface of the two-dimensional MOEMS scanning mirror assembly (3) is set to be phi 1, the working angle range of the scanning micro mirror (3.2) is set to be phi 2, and then phi 1, phi 2 and theta 1 need to satisfy the following conditions:

and theta 1<φ1。

7. The laser pulse interval processing method as claimed in claim 6, wherein: the inclination angle theta 2 of the second mirror (4) relative to the reference axis x is such that:

8. the laser pulse interval processing method as claimed in claim 7, wherein: the longitudinal distance between the center of the second reflector (4) and the center of the light window (3.1) is H2, the transverse distance is L2, and H2 and L2 need to satisfy the following conditions:

9. the laser pulse interval processing method as claimed in claim 8, wherein: the longitudinal distance between the APD detector and the receiving optical device (5) is set as H3, H3 needs to satisfy the following conditions:

wherein D is the receiving aperture of the receiving optical device (5).

10. The laser pulse interval processing method as claimed in claim 9, wherein: the relative lateral distance L3, L3 between the center of the light window (3.1) and the center of the receiving optics (5) is such that:

Technical Field

The invention relates to the technical field of laser radar ranging, in particular to a laser pulse time interval processing method and a laser radar detection system.

Background

As is known, with the rapid development of intelligent unmanned technology, the lidar technology as the "eyes" of unmanned equipment is also rapidly developed, and the core composition of the lidar is an optical detection structure, and the system composition, complexity and performance of the structure determine the volume, quality and cost of the whole lidar;

a few of the laser radars adopt the unit detectors as core structures, and the laser radars adopting the unit detectors have unique advantages in terms of volume, quality and cost, but when the laser pulse time interval is calculated, the traditional mode is that the driving signals of the laser are directly adopted as the initial reference signals of the laser pulse time interval calculation, and the initial reference signals are in random jumping phenomenon because the response time of the laser is not fixed, so that the measurement accuracy of the single pulse distance of the laser radars is greatly influenced; therefore, in view of the above, there is a need in the market for a laser radar optical detection system that is small, light, low-cost, and has high detection performance, and a laser pulse time interval processing method that can improve the accuracy of single-pulse distance measurement.

Disclosure of Invention

In order to overcome the defects in the background art, the invention discloses a laser pulse time interval processing method and a laser radar detection system.

In order to achieve the purpose, the invention adopts the following technical scheme:

the laser pulse time interval processing method comprises the following steps:

step 1: performing pulse shaping on laser emitted by a laser radar laser light source through an emitting optical device, and collimating the laser into quasi-parallel laser pulses;

step 2: quasi-parallel laser pulses are reflected to an optical window of a two-dimensional MOEMS scanning mirror assembly through a first reflecting mirror, the optical window has a light splitting function, so that a small part of the quasi-parallel laser pulses are reflected to a mirror surface of a second reflecting mirror through the optical window, and most of the quasi-parallel laser pulses are transmitted to the mirror surface of a scanning micro mirror after penetrating through the optical window of the two-dimensional MOEMS scanning mirror assembly;

and step 3: the second reflector directly reflects the corresponding quasi-parallel laser pulse to a light receiving end of the unit APD detector, the unit APD detector converts the quasi-parallel laser pulse into a corresponding electric signal, the electric signal is amplified by the transimpedance amplification circuit to obtain a laser pulse emission signal, the obtained laser pulse emission signal is output to the processor, the processor performs AND operation on the signal and a laser driving signal, and the signal after operation is used as an initial reference signal of pulse ranging;

and 4, step 4: the scanning micro-mirror reflects the corresponding quasi-parallel laser pulse to a measured object, the quasi-parallel laser pulse generates diffuse reflection on the surface of the measured object, a part of reflected laser beam is received by a receiving optical device, then the part of laser beam is focused and imaged on an APD detector, the APD detector converts the part of reflected laser beam into a corresponding electric signal, the electric signal is amplified by a transimpedance amplification circuit to obtain a laser pulse echo signal, and the laser pulse echo signal is output to a processor as a stop reference signal for pulse ranging;

and 5: the processor can accurately calculate the distance of the measured object according to the initial reference signal, the stop reference signal and the light velocity of the pulse ranging; and the stop reference signal of the pulse ranging is used as a preparation signal for the next laser pulse emission of the laser radar.

The laser radar detection system used in the method comprises a transmitting optical device, a first reflecting mirror, a two-dimensional MOEMS scanning mirror assembly, a second reflecting mirror, a receiving optical device, a unit APD detector, a transimpedance amplification circuit and a processor; the light inlet end of the transmitting optical device is correspondingly connected with a laser of the laser radar, and the light outlet end of the transmitting optical device corresponds to the mirror surface of the first reflector;

the two-dimensional MOEMS scanning mirror assembly is positioned on the right side of the transmitting optical device, a second reflecting mirror is arranged above the two-dimensional MOEMS scanning mirror assembly, the two-dimensional MOEMS scanning mirror assembly is used for receiving reflected light of the first reflecting mirror, an optical window of the two-dimensional MOEMS scanning mirror assembly can reflect a small part of received laser to a mirror surface of the second reflecting mirror, and a scanning micro mirror in the two-dimensional MOEMS scanning mirror assembly can reflect the received laser to a measured object;

the receiving optical device is positioned on the right side of the two-dimensional MOEMS scanning mirror assembly, an object to be measured is arranged above the receiving optical device, a unit APD detector is arranged below the receiving optical device and can receive reflected light of the second reflecting mirror, and a signal output end of the unit APD detector is correspondingly and electrically connected with the processor through a trans-impedance amplifying circuit;

preferably, the two-dimensional MOEMS scanning mirror assembly is of a right-angle trapezoidal structure, wherein the bevel edge is provided with an optical window, and a scanning micro mirror is arranged inside the assembly and is arranged on the inner bottom surface corresponding to the optical window;

preferably, the optical window is plated with an antireflection film corresponding to the wavelength of the laser light source;

preferably, a longitudinal distance between the center of the first mirror and the center of the optical window of the two-dimensional MOEMS scanning mirror assembly is H1, a transverse distance between the center of the first mirror and the center of the optical window of the two-dimensional MOEMS scanning mirror assembly is L1, and an inclination angle θ 1 of the first mirror relative to the reference axis x is:

preferably, the corresponding included angle between the optical window and the inner bottom surface of the two-dimensional MOEMS scanning mirror assembly is set to be phi 1, the working angle range of the scanning micro-mirror is set to be phi 2, and then phi 1, phi 2 and theta 1 are required to meet the following requirements:

and theta 1<φ1；

Preferably, the inclination angle θ 2 of the second mirror with respect to the reference axis x is such that:

preferably, the longitudinal distance between the center of the second reflector and the center of the light window is H2, and the transverse distance is L2, so that H2 and L2 satisfy the following conditions:

preferably, the longitudinal distance between the APD detector and the receiving optics is H3, H3 is satisfied:

preferably, the relative lateral distances L3, L3 between the center of the light window and the center of the receiving optics are such that:

due to the adoption of the technical scheme, the invention has the following beneficial effects:

according to the laser pulse time interval processing method disclosed by the invention, the problem of random jitter of the laser pulse flight time identification starting signal caused by unfixed response time of the laser can be solved by obtaining the accurate laser driving signal sending time, the flight time of the laser pulse from the emitting to the object to be measured can be calculated, and the accurate distance data of the object to be measured can be finally obtained.

In addition, the laser radar detection system enables the time for the laser emission pulse and the laser echo pulse to reach the APD detector to be different through the light splitting function of the optical window of the two-dimensional MOEMS scanning mirror assembly, so that the unit APD detector can perform time-sharing measurement on the laser emission pulse and the laser echo pulse, the processor obtains an accurate pulse ranging initial reference signal according to a driving signal fed back by the laser and a laser pulse emission signal measured by the unit APD detector, and finally achieves the purpose of eliminating random jitter of the initial reference signal caused by unfixed response time of the laser; in addition, the detection system uses a unit APD detector, so the radar detection system has the advantages of small volume, light weight and low cost.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of the structural parameters of the present invention.

In the figure: 1. an emission optical device; 2. a first reflector; 3. a two-dimensional MOEMS scanning mirror assembly; 3.1, an optical window; 3.2, scanning a micro mirror; 4. a second reflector; 5. a receiving optical device; 6. a cell APD detector; 7. a transimpedance amplification circuit; 8. a processor; 9. and (5) measuring the object.

Detailed Description

The present invention will be explained in detail by the following examples, which are disclosed for the purpose of protecting all technical improvements within the scope of the present invention.

A laser pulse time interval processing method described in conjunction with fig. 1-2 is:

step 1: the laser emitted by the laser radar laser light source is subjected to pulse shaping through the transmitting optical device 1 and is collimated to form quasi-parallel laser pulses, and the quasi-parallel laser pulses can ensure that laser beams are not dispersed after being reflected by a mirror surface, so that the measuring distance of the laser radar is ensured;

step 2: quasi-parallel laser pulses are reflected to an optical window 3.1 of a two-dimensional MOEMS scanning mirror assembly 3 through a first reflecting mirror 2, the optical window 3.1 has a light splitting function, so that a small part of the quasi-parallel laser pulses are reflected to a mirror surface of a second reflecting mirror 4 by the optical window 3.1, and a large part of the quasi-parallel laser pulses penetrate through the optical window 3.1 of the two-dimensional MOEMS scanning mirror assembly 3 and then reach the mirror surface of a scanning micro mirror 3.2;

and step 3: the second reflecting mirror 4 directly reflects the corresponding quasi-parallel laser pulse to the light receiving end of the unit APD detector 6, the unit APD detector 6 converts the quasi-parallel laser pulse into a corresponding electric signal, the electric signal is amplified by the transimpedance amplifier circuit 7 to obtain a laser pulse emission signal and output the laser pulse emission signal to the processor 8, the processor performs AND operation on the obtained laser pulse emission signal and a laser driving signal, and the signal after operation is used as an initial reference signal of pulse ranging;

and 4, step 4: the scanning micro-mirror 3.2 reflects the corresponding quasi-parallel laser pulse to the object to be measured 9, the quasi-parallel laser pulse is subjected to diffuse reflection on the surface of the object to be measured 9, part of the reflected laser beam is received by the receiving optical device 5, then the part of the laser beam is focused and imaged on the APD detector, the unit APD detector 6 converts the part of the laser beam into a corresponding electric signal, the electric signal is amplified by the transimpedance amplification circuit 7 to obtain a laser pulse echo signal, and the laser pulse echo signal is output to the processor 8 as a stop reference signal for pulse ranging;

and 5: the processor 8 can accurately calculate the distance of the object to be measured 9 according to the initial reference signal, the stop reference signal and the light velocity of the pulse ranging; and the stop reference signal of the pulse ranging is used as a preparation signal for the next laser pulse emission of the laser radar,

the laser radar detection system used in the method comprises a transmitting optical device 1, a first reflecting mirror 2, a two-dimensional MOEMS scanning mirror assembly 3, a second reflecting mirror 4, a receiving optical device 5, a unit APD detector 6, a transimpedance amplification circuit 7 and a processor 8; the light inlet end of the transmitting optical device 1 is correspondingly connected with a laser of a laser radar, and the light outlet end of the transmitting optical device 1 corresponds to the mirror surface of the first reflector 2;

two-dimentional MOEMS scanning mirror assembly 3 is located emission optical device 1's right side, and two-dimentional MOEMS scanning mirror assembly 3's top is equipped with second mirror 4, and two-dimentional MOEMS scanning mirror assembly 3 is used for receiving the reverberation of first mirror 2, and two-dimentional MOEMS scanning mirror assembly 3's optical window 3.1 can reflect the mirror surface of second mirror 4 with the small part laser of receipt, and is special, optical window 3.1 is plated with the antireflection coating corresponding with laser source wavelength, and scanning micro mirror 3.2 in two-dimentional MOEMS scanning mirror assembly 3 can be with the laser reflection of receipt to measured object 9, in addition, two-dimentional MOEMS scanning mirror assembly 3 establishes to right trapezoid structure, and wherein the hypotenuse is established to optical window 3.1, and the inside of subassembly is equipped with scanning micro mirror 3.2, and this scanning micro mirror 3.2 is installed at the interior bottom surface corresponding with optical window 3.1, makes optical window 3.1 have certain inclination for scanning micro mirror 3.2 to guarantee that the laser beam that optical window 3.1 reflects and the laser beam of scanning micro mirror 3. Reflecting by a measured object 9;

the receiving optical device 5 is positioned on the right side of the two-dimensional MOEMS scanning mirror assembly 3, a measured object 9 is arranged above the receiving optical device 5, a unit APD detector 6 is arranged below the receiving optical device 5, the unit APD detector 6 can receive reflected light of the second reflecting mirror 4, and a signal output end of the unit APD detector 6 is correspondingly and electrically connected with the processor 8 through a transimpedance amplification circuit 7;

in addition, numerical values such as the interval of each part, angle in this laser radar detection system need reasonable design, and the concrete design of each parameter is:

the longitudinal distance between the center of the first reflecting mirror 2 and the center of the optical window 3.1 of the two-dimensional MOEMS scanning mirror assembly 3 is H1, the transverse distance between the center of the first reflecting mirror 2 and the center of the optical window 3.1 of the two-dimensional MOEMS scanning mirror assembly 3 is L1, and the inclination angle θ 1 of the first reflecting mirror 2 relative to the reference axis x is:

the angle range of theta 1 is restricted by H1 and L1, so that the laser beam reflected by the first reflecting mirror 2 can fall in the middle of an optical window of the two-dimensional MOEMS scanning mirror assembly 3;

the corresponding included angle between the optical window 3.1 and the inner bottom surface of the two-dimensional MOEMS scanning mirror assembly 3 is set to be phi 1, the working angle range of the scanning micro-mirror 3.2 is set to be phi 2, and then phi 1, phi 2 and theta 1 need to meet the following requirements:

and theta 1<φ1；

By specifying the relationship among the three angles, the light window 3.1 and the scanning micro mirror 3.2 can both receive the reflected light output by the first reflecting mirror 2, and the light window 3.1 and the scanning micro mirror 3.2 reflect the reflected light to different places;

the inclination angle θ 2 of the second mirror 4 with respect to the reference axis x is such that:

by limiting the angle range of theta 2, the second reflector 4 can be ensured to receive the reflected light output by the optical window 3.1, and then the laser beam is directly reflected to the APD detector 6;

the longitudinal distance between the center of the second reflecting mirror 4 and the center of the light window 3.1 is H2, the transverse distance is L2, and H2 and L2 satisfy the following conditions:

the length of the L2 is limited by the relation between H2 and theta 2, so that the position relation between the two-dimensional MOEMS scanning mirror assembly 3 and the reflecting mirror 4 is ensured to meet the transmission path requirement set by the laser beam;

the longitudinal distance between the front surface of the APD detector 6 and the rear end of the receiving optical device 5 is H3, H3 is required to satisfy:

and D is the receiving aperture of the receiving optical device 5, and the receiving optical device 5 does not block the laser beam reflected by the reflecting mirror 4 by limiting H3. (ii) a

The relative lateral distances L3, L3 between the center of the light window 3.1 and the center of the receiving optics 5 are such that:

by integrating the calculation steps, the position and angle relation of each component of the detection system can be obtained, so that the APD detector 6 can perform time-sharing measurement on laser emission pulses and laser echo pulses, the processor can accurately calculate the flight time of laser, and the accurate distance data of the measured object can be finally obtained. The present invention is not described in detail in the prior art.