Research On Fabrication&Calibration Of High-precision Image Lidar

LiDAR is a laser ranging technology that can obtain environmental spatial information.It is an important part of autonomous driving technology and intelligent navigation technology.As the requirements for intelligent systems become higher,the high precision of lidar has become a research hotspot.The development of LiDAR is limited by the low resolution of detectors.The highest resolution of solid-state FLASH lidar is only 64×64 in my country.The APD array detector is used as the receiving end of the lidar.It has the ability of single photon detection,with high sensitivity,high distance resolution,high imaging speed.However,it has imaging deficiencies in terms of nonlinearity and non-uniformity.This project aims to improve the above issues in the following aspects:(1)Aiming at the low resolution of laser radar,a hybrid laser radar system based on MEMS and FLASH is built.The MEMS is the transmitter.The laser emits laser light in time division to form a 4×4 spatial lattice.The 64×64 GMAPD is the receiver,and 256×256 resolution achieved by stitching 16 fields of view.Complete the logic design of MEMS drive and system synchronization.A hybrid solid-state lidar with a band of 1550nm and a resolution of 256×256 has been realized.(2)For the nonlinearity of the Geiger shortwave infrared APD array detector,calibration is performed.The photon counting response of the GMAPD array is nonlinear with linearly increasing number of incident photons.Establish a singlephoton detector radiation response calibration model,obtain the nonlinear response through calibration experiments,and obtain the correction formula through inversion,and finally realize the large dynamic measurement of 1.2×10-2～1.2W/(m2Sr)target radiance,and the response linearity from 83.3%to 91.8%.(3)Aiming at the non-uniformity of the Geiger short-wave infrared APD array detector,the compensation is performed.For an array APD detector composed of multiple detection units,When light of the same intensity is incident,the output photon count value of each pixel detector is different.A calibration model based on the diffuse reflector is established,and the least squares method is used to correct it.the bad points were calibrated based on a single pixel and the threshold method based on the area array,and the mean value convolution method was assigned to it.The mean value convolution method is used to assign values to them.Non-uniformity decreased from 10.87%to 5.84%.In summary,imaging lidar has been systematically improved in terms of spatial dimension,response rate,and consistency.