Design Of Non-scanning Lidar Optical System Based On APD Array

In order to realize the detection of ground targets in the range of 10m×10m and1 km,the existing 3D active imaging lidar is analyzed in this thesis.According to the working mode,active imaging radar is divided into scanning type and non-scanning type.Scanning radar is the most commonly used laser radar.Since the research in the last century,the related technology has been very mature,but its large size,heavy weight,and imaging rate Low and other shortcomings,can no longer meet the current needs.Airborne 3D imaging lidar is used in real-time imaging and identification of ground targets.It requires high imaging rate and miniaturization of the system.In response to the above requirements,this thesis plans to use a non-scanning lidar imaging system.Since the non-scanning lidar system has no scanning device,the volume is small,and the imaging error caused by the scanning device is avoided,and the target object can be imaged without distortion.Because it adopts the imaging method of detecting the entire target with one launch,that is,"flash" imaging,it brings infinite possibilities for real-time imaging of lidar.However,this detection method can obtain one image in a single detection,so while achieving a wide field of view,because the laser power and detector detection capabilities are limited,the optical system cannot effectively use the laser energy,and due to the influence of atmospheric transmission and target characteristics,the echo signal is very weak,so the detection distance of the non-scanning method is usually relatively short.In order to make full use of light energy,this subject uses a combination of Galileo telescope and microlens array to construct a lattice illumination system in the transmitting optical system to illuminate the target in an array;at the same time,the application of the microlens array in imaging is used in the receiving optical system,and it is combined with the array detector to improve the detection capability of the detector.The main task of this topic is to improve the utilization rate of light energy by the radar system through the design of the optical system,thereby improving the detection distance of the lidar.1.In order to detect the object at a distance of 1 km and within the range of10m×10m,in view of the requirements of miniaturization and high imaging rate of lidar,this thesis decided to use APD array as the detector to receive the weak signal.Through the analysis of the detection target,the components used in the system are selected.At the same time,according to the characteristics of the illumination system and the characteristics of the detection system,the non-scanning laser radar ranging system is modeled,and the index requirements of the optical system are put forward.2.Design of non-scanning lidar optical system.First of all,in the emission optical system,in order to make full use of light energy and improve the uniformity of light intensity distribution to achieve array illumination,this topic introduces a microlens array,and uses the spectroscopic properties of the microlens array to divide the light beam into corresponding sub-beams to form a lattice spot.In the receiving optical system,in order to match the APD array detector,the echo beam incident on the pixel area should be focused on a smaller photosensitive surface as much as possible.The focusing characteristics of the microlens array are used to improve the filling factor of the detector,thereby further improving the utilization rate of light energy.3.Simulation of a non-scanning lidar optical system.The simulation results show that using the microlens array can effectively improve the utilization rate of the light energy emitted by the laser.At the same time,considering the light energy loss and other issues,the optical path was improved.It was proved by simulation that the optical energy loss of the laser was greatly reduced,the utilization rate of light energy was improved,and the feasibility of the application of the microlens array in lattice illumination and array detectors was verified..According to the non-scanning lidar distance equation,the system can achieve detection at a distance of 1km.Based on the above analysis of the application of microlens array to non-scanning lidar,this optical system has the possibility of realizing array illumination,which is of great significance in improving the utilization rate of light energy,and lays the foundation for the next exploration of non-scanning imaging lidar system.