CN103412313B - Small low-altitude light area array laser radar measuring system - Google Patents

Abstract

The invention discloses a low-altitude, light and small area array laser radar measurement system. The main control subsystem of the measurement system triggers the pulse laser emission module to emit laser light. After collimation, two laser signals are generated through the beam splitter. One path is used to determine the laser emission time and generate a timing start signal, and the other path irradiates the target through beam expansion. The echo signal is received by the APD array detection module and generates N ² stop pulses. The multi-channel high-precision time interval measurement module combines the start signal to measure the round-trip flight time difference of N ² lasers in a rectangular detection area. The position and attitude measurement subsystem, the main control subsystem and the area array lidar ranging subsystem of the measurement system are integrated into one, which can obtain the original three-dimensional information in real time, eliminating the need for assembly and calibration. The laser radar measurement system of the present invention can perform three-dimensional imaging with a single pulse without scanning, has fast imaging speed, high measurement accuracy and work efficiency, small size and light weight, and is suitable for carrying on a low-altitude, light and small remote sensing platform.

Description

Low-altitude light and small area array laser radar measurement system

technical field

The invention relates to laser radar technology in the field of active optical aerial remote sensing payloads, in particular to an area array laser radar measurement system suitable for carrying on a low-altitude light and small remote sensing platform.

Background technique

Lidar measurement is an active optical remote sensing technology that has rapidly developed into a hot spot. It provides an important means for obtaining three-dimensional space data, and is suitable for target detection, earth observation, three-dimensional modeling of urban buildings, and traffic lines, power lines, Survey and planning of oil and gas pipelines, etc. The laser radar measurement system includes a laser ranging unit, a position and attitude measurement unit and a main control unit. It uses the distance information measured by the laser ranging unit, and then combines the position and attitude information obtained by the position and attitude measurement unit at the time of laser ranging to solve the precise three-dimensional coordinates of the detection target, thereby realizing three-dimensional imaging. These three units are separated from each other in the conventional lidar measurement system. Each use needs to be assembled and disassembled. Each disassembly will cause the parameters to change. If you want to collect high-precision data, you need to re-check before use. This method of combining discrete units not only affects the efficiency of use, but also leads to an increase in the volume and weight of the entire lidar measurement system, making it difficult to achieve light weight and miniaturization.

The laser ranging unit is the core of the laser radar measurement system. It emits a beam of laser light to illuminate the target through the laser transmitter, and then the receiver converts the echo signal reflected by the target into an electrical signal, and then obtains the measurement system through the laser radar processor. The distance value to the target object. The traditional laser ranging unit adopts the method of single-point emission and single-point reception, which requires high repetition frequency of the laser and needs to cooperate with a mechanical scanning device to image. Not only is it large in size and power consumption, but it also reduces the imaging speed and limits its application. scope.

In order to overcome the shortcomings of scanning single-point detection, research on the area array lidar measurement system has begun internationally. At present, ICCD (Intensified Charge-coupled Device) is mainly used for three-dimensional imaging. Chinese Invention Patent Specification CN101498786A and "Optoelectronic Engineering" Journal, Volume 40, No. 2, February 2013, "Staring Imaging Lidar Based on Area Array Detectors", both disclose the research of ICCD area array detectors for non-scanning three-dimensional imaging. However, there are some shortcomings in this method. First, the ICCD area array detector cannot directly obtain the distance information. It needs to use modulation and demodulation, and at least two intensity images can be used to calculate the distance image, resulting in a large amount of data processing. At the same time, the processing Second, due to the modulation and demodulation method, a modulator with an additional high-voltage modulation power supply must be used when receiving echo signals, and a demodulator for processing intensity images must be used when generating three-dimensional information. The device makes the lidar measurement system complex to implement, and the volume and weight are still large, making it difficult to be light and small; third: the ranging error obtained in the above journal literature is 0.6m, which cannot meet the low-altitude detection that requires high distance accuracy occasion.

APD (Avalanche Photo Diode) is an N×N APD array detector integrated with multiple independent APD unit detectors, which has compact structure, small size and light weight. Compared with the APD unit detector, it can realize non-scanning laser detection and three-dimensional imaging with a single pulse; compared with the ICCD detector, the APD array detector can directly obtain three-dimensional information, the imaging speed is faster, and the system structure is simple.

Compared with the single-point laser ranging method, the area array laser ranging method needs to emit a single pulse laser to illuminate a larger target area. When performing long-distance detection, the single pulse laser is required to reach a very high peak power. High requirements are imposed, and the volume, weight and cost of the laser will increase.

Contents of the invention

The purpose of the present invention is to provide a low-altitude, light and small area array laser radar measurement system in order to solve the problems existing in the existing laser radar measurement system proposed above. The measuring system of the present invention does not need to scan, can image three-dimensionally with a single pulse, has fast imaging speed, high measurement accuracy and work efficiency, and has significantly reduced volume and weight, and is suitable for carrying on a low-altitude light and small remote sensing platform.

The low-altitude, light and small area array laser radar measurement system of the present invention is realized from the following four aspects. The recently developed APD area detector can detect N×N points in a rectangular area with a single pulse through direct detection without scanning device. The system has compact structure, fast imaging speed and high detection efficiency. Second: use a high-resolution timing chip to develop a multi-channel high-precision time interval measurement module, which can measure the time difference of N ² paths of laser round-trip flight in parallel each time, and calculate N×N target measurements in the detection area according to the laser ranging formula The distance information of the point, the test shows that the ranging error is less than 0.12m. Third: The laser radar measurement system of the present invention integrates the position and attitude measurement subsystem, the main control subsystem and the area array laser radar ranging subsystem, which reduces the volume of the measurement system and eliminates the need for pre-use assembly and maintenance. The parameters are re-checked to improve the use efficiency; Fourth: the present invention is based on low-altitude remote sensing applications, and can choose light and small pulse lasers with low peak power as light sources, further reducing the size and weight of the laser radar measurement system.

The low-altitude, light and small area array laser radar measurement system of the present invention includes a position and attitude measurement subsystem, a main control subsystem and an area array laser radar ranging subsystem.

The position and attitude measurement subsystem consists of a GPS (Global Positioning System) receiver and an attitude measurement module.

The main control subsystem consists of a microcontroller, timers and memory.

The area array lidar ranging subsystem consists of a pulse laser emission module, a collimator lens, a beam splitter, a total reflection mirror, a beam expander emission lens, a PIN high-speed photoelectric detection module, a receiving lens, an adjustable focal plane lens, a filter, and an APD array It consists of a detection module and a multi-channel high-precision time interval measurement module.

The GPS receiver is used to provide PPS (pulses per second) as the start signal of the measurement system and to obtain the latitude and longitude, elevation and UTC (Coordinated Universal Time) of the measurement system, that is, the time information of the coordinated universal time; the attitude measurement module is used It is used to obtain the heading angle, pitch angle and roll angle information of the measurement system.

As the control center of the measurement system, the microcontroller starts the work of the measurement system under the trigger of the PPS signal, controls the timing of the timer, reads the position information of the GPS receiver, controls the work of the attitude measurement module and reads its attitude information, triggers The pulsed laser emission module emits laser light, reads the time data of the multi-channel high-precision time interval measurement module and converts it into distance information, and stores these three kinds of information plus time synchronization tags in the memory; the memory is a lightweight large-capacity memory for Store the data collected by the measurement system; the timer starts counting when the microcontroller receives the PPS signal, records the time difference of the three moments of GPS receiver positioning, attitude measurement module attitude measurement, and pulse laser emission module emitting laser, and records the time difference As the three time synchronization tags, the data collected by them is unified to UTC time based on the UTC time provided by GPS, so as to achieve the purpose of synchronization.

The pulse laser emission module needs to have the characteristics of high power, narrow pulse, and adjustable output frequency. As the emission light source of this measurement system, its working wavelength needs to match the filter and APD array detection module; it consists of a collimator lens and a beam expander emission lens The transmitting optical system, the receiving lens, the focal plane adjustable lens and the filter form the receiving optical system. The transmitting optical system and the receiving optical system adopt the transmission telescope method of light emitting/receiving parallel optical path structure; the transmitting optical system is used for collimating pulsed laser The laser beam emitted by the transmitting module is expanded and irradiated to the target. The divergence angle of the collimated laser is determined according to the requirement that the detection distance meets the required detection target area; The final laser is divided into two laser beams with a large splitting ratio; the PIN high-speed photoelectric detection module detects the smaller laser beam separated by the splitter, which is used as the mark of the laser emission time and the start signal of the multi-channel high-precision time interval measurement module; The receiving lens in the optical system is used to receive the laser light reflected back from the target and focus it on the focal plane adjustable lens, which needs to meet the requirements of the receiving field angle of the APD array detection module. The position and size of the focal plane of the laser ensure that the echo signal covers the entire photosensitive surface, and cooperate with the receiving lens to meet the requirements of optical power density and receiving field of view. The filter is used to filter out the laser light outside the working wavelength and suppress the interference of background light; APD The array detection module is an N×N (N≧8) array avalanche photoelectric detection module working in linear mode. After the echo signal passes through photoelectric detection and signal processing, it generates N ² stop signals, and its avalanche voltage is boosted by a low-voltage DC power supply. Provided, the bias voltage and comparator reference level are adjustable, and the output impedance meets the impedance matching with the multi-channel high-precision time interval measurement module; the multi-channel high-precision time interval measurement module is used to measure the N ^2- way time interval of the laser round-trip flight, Then calculate the distance information of N ² target measurement points representing a rectangular area according to the laser ranging formula. The number of channels of the multi-channel high-precision time interval measurement module is greater than or equal to the number of units of the APD array. In order to obtain high-precision distance information, each The channel needs to meet the high-precision timing requirements.

The working steps of the low-altitude light and small area array laser radar measurement system of the present invention are:

(1) When the microcontroller receives the PPS signal generated by the GPS receiver, the timer is triggered to start counting.

(2) The microcontroller reads the position information and UTC time information of the GPS receiver and saves them in the memory, then controls the attitude measurement module to work, reads the output attitude information and saves it to the memory with a time synchronization tag.

(3) The microcontroller controls the peripheral drive circuit to output TTL level, triggers the pulsed laser emitting module to emit laser, the emitted laser is collimated by the collimator lens and then passes through the beam splitter to generate two laser signals, and a small part of the reflected laser passes through the total reflection The mirror enters the PIN high-speed photoelectric detection module to generate the start signal and the laser emission time monitoring signal, and input the START terminal of the multi-channel high-precision time interval measurement module and the interrupt port of the microcontroller respectively, and most of the transmitted laser light is irradiated by the beam expanding emission lens The target, the laser reflected by the target is focused to the focal plane adjustable lens through the receiving lens, and then converged to the APD array detection module through the filter to generate N ² stop signals, which are respectively input to the N ² STOPs of the multi-channel high-precision time interval measurement module At the end, the N ² time data obtained by multi-channel high-precision timing are transmitted to the microcontroller through the serial port, and then converted into N ² distance values representing a rectangular area by the laser ranging formula, and then saved to the memory after adding a time synchronization label middle.

(4) Repeat steps (2) and (3) until the original 3D information of the entire imaging area is obtained.

(5) After the remote sensing platform lands on the ground, the data is post-processed to generate an accurate three-dimensional image.

Compared with the prior art, the present invention mainly has the following advantages:

1) The present invention uses a high-resolution timing chip to develop a multi-channel high-precision time interval measurement module, which can measure the round-trip flight time difference of N ² lasers in parallel each time, and can obtain distance information with an error of about 0.12m in the target detection area.

2) Compared with single-point scanning laser radar, the present invention realizes non-scanning laser detection, a single laser pulse can generate a three-dimensional image, the imaging efficiency is high, and the requirement for laser repetition frequency is low; compared with ICCD area array detection laser radar, the present invention It does not require modulation and demodulation, simplifies the system structure, and can quickly and directly obtain three-dimensional information, meeting the requirements of light and small remote sensing platforms.

3) The present invention integrates the position and attitude measurement subsystem, the main control subsystem and the area array lidar ranging subsystem into one, which can obtain the original three-dimensional information in real time on the remote sensing platform, and avoids the assembly of each subsystem during use and recheck the parameters.

4) The present invention is based on low-altitude remote sensing applications, and can choose light and small pulse lasers with low peak power as light sources, which further reduces the size and weight of the lidar measurement system. In addition, low-altitude operations are less affected by climate conditions. Airspace application is convenient and can be put into use more quickly.

Description of drawings

Fig. 1 is a working schematic diagram of the laser radar measurement system of the present invention mounted on an unmanned aerial vehicle.

Fig. 2 is a structural principle block diagram of the present invention.

Marks in the figure: 1 - position and attitude measurement subsystem; 101 - GPS receiver; 102 - attitude measurement module.

2-main control subsystem; 201-microcontroller; 202-timer; 203-memory.

3-area laser radar ranging subsystem; 301-pulse laser emission module; 302-collimator lens; 303-beam splitter; 304-full mirror; 305-beam expander emission lens; 307-receiving lens; 308-focal plane adjustable lens; 309-filter; 310-APD array detection module; 311-multi-channel high-precision time interval measurement module.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example:

As shown in the working schematic diagram in Figure 1, the laser radar measurement system of this embodiment is carried on a small unmanned aerial vehicle at a low altitude of 200m for three-dimensional data acquisition work, and a single laser pulse can detect a target area of 5m × 5m, and the generated three-dimensional image The distance error is less than 0.12m, and the pixel pitch is 0.625m.

As shown in Figure 2, the low-altitude light and small area array lidar measurement system includes position and attitude measurement subsystem 1, main control subsystem 2 and area array lidar ranging subsystem 3.

The position and attitude measurement subsystem 1 is composed of a GPS receiver 101 and an attitude measurement module 102 .

The main control subsystem 2 is composed of a microcontroller 201 , a timer 202 and a memory 203 .

The area array lidar ranging subsystem 3 consists of a pulsed laser emitting module 301, a collimating lens 302, a beam splitter 303, a total reflection mirror 304, a beam expanding emitting lens 305, a PIN high-speed photoelectric detection module 306, a receiving lens 307, and a focal plane adjustable It is composed of an adjustable lens 308, a filter 309, an APD array detection module 310 and a multi-channel high-precision time interval measurement module 311.

The collimating lens 302 and the beam expander transmitting lens 305 form the transmitting optical system, and the receiving lens 307, the focal plane adjustable lens 308 and the filter plate 309 form the receiving optical system, and the transmitting optical system and the receiving optical system adopt the light emitting/receiving parallel light path structure Transmissive telescope mode.

Described GPS receiver 101 is used for providing PPS signal, UTC time information and the position information of this measurement system, adopts the differential GPS receiver of Canadian NovAtel company OEMV-2 model, the horizontal position accuracy is 0.45m, and the update frequency can reach 50HZ, communicate with microcontroller 201 through RS232 serial interface.

The attitude measurement module 102 is used to obtain the attitude information of the measurement system, and adopts an inertial measurement unit (IMU) (Inertial measurement unit), which is an inertial measurement unit, and the data update frequency can reach 100HZ. The errors of the three attitude angles are less than 0.08°, and the RS232 serial interface is used to communicate with the microcontroller 201 .

The microcontroller 201 is a 32-bit ARM-core microcontroller. As the control center of the measurement system, the STM32 high-performance low-power consumption product of STMicroelectronics is adopted. The clock frequency is up to 120MHZ, and 2 USB (Universal Serial BUS) is the universal serial bus, with up to 15 communication interfaces, up to 17 16-bit and 32-bit timers, with a built-in flash memory capacity of up to 1MHZ and easy expansion of storage capacity.

Described timer 202 starts timing after microcontroller receives the PPS signal of GPS receiver 101, records the working time difference of GPS receiver 101, attitude measurement module 102, pulsed laser emission module 301 as the time synchronization label of the three, The data collected by the three are unified to the UTC time to achieve the purpose of synchronization, and the 32-bit timer provided by the microcontroller 201 is used.

The memory 203 is a portable large-capacity memory for storing the data collected by the measurement system. SD card (Secure Digital Memory Card) is used, which is a secure digital card, which weighs only 1.5g, has a capacity of 32GB, and an access speed of up to 30MB/s.

The pulsed laser emitting module 301, as the emitting light source of the measurement system, adopts a pulsed microchip laser module with an output center wavelength of 905 nm, a pulse width of 8 ns, a peak power of 29 kw, and an adjustable repetition rate.

The transmissive emitting optical system composed of the collimating lens 302 and the beam expanding emitting lens 305 is used to collimate the laser beam emitted by the pulsed laser emitting module and irradiate the target after beam expansion, and the laser divergence angle after collimation is 35 mrad , in order to improve the emission efficiency, the collimating lens 302 needs to be coated with a 905nm anti-reflection coating.

The beam splitter 303 splits the collimated laser light into two laser beams with a ratio of reflected light and transmitted light of 1:999.

The total reflection mirror 304 makes the smaller laser beam split by the beam splitter 303 incident to the PIN high-speed photoelectric detection module 306 .

The PIN high-speed photoelectric detection module 306 is used to detect the laser incident by the total reflection mirror 304, and the electric pulse signal generated is used as the mark of the laser emission time and the start signal of the multi-channel high-precision time interval measurement module 311. The GT106 high-speed PIN photodiode of Ke 44 Institute detects the incident laser light, and then the required electrical pulse signal is generated by the transimpedance amplifier circuit and the high-speed comparator circuit.

The receiving lens 307 is an aspheric lens with a diameter of 120mm and a focal length of 100mm, which is used to receive the laser light reflected from the target and focus it on the focal plane adjustable lens 308. In order to improve the receiving efficiency, the receiving lens 307 is coated with a 905nm antireflection film .

The focal plane adjustable lens 308 is used to adjust the position and size of the laser focal plane converged by the receiving lens 307 to ensure that the echo signal covers the entire photosensitive surface and meet the requirements of optical power density and receiving field angle. The focal plane adjustable lens 308 is coated with a 905nm anti-reflection film.

The filter 309 is a 905nm filter with a bandwidth of ±10nm and a transmittance greater than 85%, which is used to filter out laser light other than the working wavelength and suppress the interference of background light.

The APD array detection module 310 is an avalanche photoelectric detection module of an N×N array working in a linear mode, which receives echo signals in the field of view, conducts photoelectric detection through an 8×8 APD array, and consists of 64 independent high-speed Transimpedance operational amplifier and comparator two-stage circuit process to generate 64 stop signals to realize photoelectric detection of one surface. Using the 8×8 APD array of first sensor company, the responsivity at 905nm is 60A/W, its avalanche voltage is 200V, the high voltage bias voltage is boosted by 5V power supply, and the bias voltage and comparator reference level are adjustable , 50 ohm output impedance.

The multi-channel high-precision time interval measurement module 311 has an input impedance of 50 ohms, and is used to measure the multi-path time difference of the round-trip flight of the laser, and then obtain the distance information of the target measurement point representing a rectangular area. The 8-channel TDC-GPX chip with a timing resolution of 81 picoseconds from the German ACAM company is adopted. Under the control of the ARM core micro-control unit or FPGA (Field-Programmable Gate Array), the field-programmable gate array is controlled by chip selection, and 8 chips are used. The TDC-GPX chip is developed and can measure the time interval between the 64 stop signals output by the APD array detection module 310 and the start signal in parallel. This module communicates with the microcontroller 201 through a USB interface.

The working steps of this measurement system are:

(1) When the microcontroller receives the PPS signal generated by the GPS receiver 101, the timer 202 is triggered to start timing.

(2) The microcontroller 201 reads the position information and UTC time information of the GPS receiver 101 and saves them in the memory 203, then controls the attitude measurement module 102 to work, reads the attitude information output by it and saves it to the memory with a time synchronization tag 203.

(3) Microcontroller 201 controls the peripheral drive circuit to output TTL level trigger pulse. Laser emitting module 301 emits laser light. The emitted laser light is collimated by collimator lens 302 and then passes through beam splitter 303 to generate two laser signals. A small part of the reflected laser light Enter the PIN high-speed photoelectric detection module 306 through the total reflection mirror 304 to generate the start signal and the laser emission time monitoring signal and input the START end of the multi-channel high-precision time interval measurement module 311 and the interrupt port of the microcontroller 201 respectively, most of the transmitted laser light The target is irradiated after the beam is expanded by the beam expanding transmitting lens 305, and the laser light reflected by the target is focused to the focal plane adjustable lens 308 by the receiving lens 307, and then converged to the APD array detection module 310 through the filter 309 to generate 64 stop signals respectively input to multiple The 64 STOP terminals of the channel high-precision time interval measurement module 311, the 64 channels of time data obtained by the multi-channel high-precision timing are transmitted to the microcontroller 201 through the serial port, and then converted into the 5m×5m square target area by the laser ranging formula. The 64 distance values are stored in the memory 203 after being added with a time synchronization tag.

(4) Repeat steps (2) and (3) until the original three-dimensional information of the imaging area required by the task is obtained.

(5) After the drone lands on the ground, the data is post-processed to generate an accurate three-dimensional image. the

The above disclosure is only an embodiment of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, without departing from the principle of the present invention, the deformations made should be regarded as belonging to the present invention protected range.

Claims (1)

1. a small low-altitude light area array lidar measurement system, is characterized in that small low-altitude light area array lidar measurement system comprises position and attitude measurement subsystem (1), main control subsystem (2) and face battle array laser radar range subsystem (3);

Position and attitude measurement subsystem (1) is made up of global positioning system and GPS (101) and attitude measurement module (102);

Main control subsystem (2) is made up of microcontroller (201), timer (202) and memory (203);

Face battle array laser radar range subsystem (3) by pulse laser emission module (301), collimation lens (302), light splitting piece (303), total reflective mirror (304), expand diversing lens (305), PIN high speed optoelectronic detecting module (306), receiver lens (307), focal plane adjustable lens (308), filter plate (309), avalanche photodiode array and APD array detection module (310) and multi-channel high-accuracy time interval measurement module (311) forms;

GPS (101) is for providing PPS and pps pulse per second signal as the enabling signal of this measuring system and obtaining the longitude and latitude of this measuring system, elevation and UTC Universal Time Coordinated and UTC temporal information; Attitude measurement module (102) is for obtaining the course angle of this measuring system, the angle of pitch and angle of roll information;

Microcontroller (201) is as the control centre of this measuring system, the work of this measuring system is started under the triggering of PPS signal, control timer (202) timing, read the positional information of GPS (101), control attitude measurement module (102) work and read its attitude information, trigger impulse laser emitting module (301) Emission Lasers, read multi-channel high-accuracy time interval measurement module (311) time data and be converted into range information again, and these three kinds of information are added that time synchronized label is kept at memory (203); Memory (203) is legerity type mass storage, for storing the data that this measuring system gathers; Timer (202) receives PPS signal at microcontroller (201) and namely starts timing, appearance, the time difference in these three moment of pulse laser emission module (301) Emission Lasers are surveyed in record GPS (101) location, attitude measurement module (102), and using the time difference as three's time synchronized label, the UTC time provided with GPS (101) be benchmark data unification that they are gathered on the UTC time, thus reach synchronous object;

Pulse laser emission module (301) is as the transmitting illuminant of this measuring system, and its operation wavelength needs to mate with filter plate and APD array detection module (310), collimation lens (302) and expand diversing lens (305) composition optical transmitting system, receiver lens (307), focal plane adjustable lens (308) and filter plate (309) composition receiving optics, optical transmitting system and receiving optics adopt the transmission-type telescope mode of light transmitting/receiving parallel optical structure, optical transmitting system is used for the laser beam launched of collimated pulsed laser transmitter module (301) and is irradiated to target after expanding, and the requirement that the laser beam divergence size after collimation meets once required detection of a target area according to detection range is determined, light splitting piece (303) and total reflective mirror (304) form the two bundle laser of spectroscope for being divided into splitting ratio very large laser after collimation, the compare little mono-road laser that PIN high speed optoelectronic detecting module (306) detection light splitting piece (303) separates, as the mark in Laser emission moment and the commencing signal of multi-channel high-accuracy time interval measurement module (311), the laser that receiver lens (307) in receiving optics reflects for receiving target also focuses on focal plane adjustable lens (308), the requirement at APD array detection module (310) field of view of receiver angle need be met, wherein position and the size of focal plane adjustable lens (308) for regulating receiver lens (307) to assemble rear laser focal plane, ensure that echo-signal covers whole photosurface, receiver lens (307) is coordinated to meet optical power density and the requirement of field of view of receiver angle, filter plate (309) is for the laser outside filtering operation wavelength, the interference of Background suppression light, APD array detection module (310) is for being operated in N × N array avalanche optoelectronic detecting module of linear model, and N≤8, echo-signal is by producing N after photodetection and signal transacting ²road stop signal, its avalanche voltage is provided by boosting by low-voltage dc power supply, bias voltage and comparator reference level adjustable, output impedance and multi-channel high-accuracy time interval measurement module (311) meet impedance matching, multi-channel high-accuracy time interval measurement module (311) is for measuring the N of laser shuttle flight ²the road time interval, then the N going out to represent a rectangular area according to laser ranging formulae discovery ²individual target measurement point range information, multi-channel high-accuracy time interval measurement module (311) port number is more than or equal to the unit number of APD array, and for obtaining high-precision range information, each passage need meet high-precision timing requirement,

The job step of small low-altitude light area array lidar measurement system is:

(1) after microcontroller (201) receives the PPS signal that GPS (101) produces, triggered timer (202) starts timing;

(2) microcontroller (201) read GPS (101) positional information and UTC temporal information be kept in memory (203), then control attitude measurement module (102) work, read its attitude information exported and add that time synchronized label is saved in memory (203);

(3) microcontroller (201) controls peripheral drive circuit and exports Transistor-Transistor Logic level, trigger impulse laser emitting module (301) Emission Lasers, the laser sent produces two-way laser signal by light splitting piece (303) after collimation lens (302) collimation, the fraction laser of reflection enters PIN high speed optoelectronic detecting module (306) by total reflective mirror (304) and produces commencing signal and Laser emission moment supervisory signal, and input the START end of multi-channel high-accuracy time interval measurement module (311) and the middle fracture of microcontroller (201) respectively, most of laser of transmission irradiates target through expanding diversing lens (305), the laser that target reflects focuses on focal plane adjustable lens (308) through receiver lens (307), then converge to APD array detection module (310) by filter plate (309) and produce N ²road stop signal, inputs the N of multi-channel high-accuracy time interval measurement module (311) respectively ²individual STOP end, the N that duplex high precision timing obtains ²road time data to microcontroller (201), then is converted into the N representing a rectangular area by Serial Port Transmission by laser ranging formula ²individual distance value, is saved in memory (203) after adding time synchronized label,

(4) step (2) and step (3) work is repeated, until obtain the initial three-dimensional information of whole imaging region;

(5) treat that remote sensing platform landing ground is through Data Post, generates accurate 3-D view.