High Definition Laser Ranging Radar System Hardware Design

Since Laser Radar(Ladar) was put forward in 1961, it has achieved considerable development. Linear frequency modulation continuous wave Ladar(LFMCW Ladar) is one of the most important branches, it is widely used in Environmental Remote Sensing,Atmospheric Monitoring and High Definition Ranging, etc.This thesis focus on the application of LFMCW Ladar in High Definition Ranging,especially in the generation and reception of wide band linear frequency modulation wave of laser. Based on Distributed Feedback(DFB) Semiconductor Laser, this thesis introduces the design of the generation module and receiving module of linear frequency modulation wave of laser. This technology is the foundation of 3D Ladar imaging and Synthetic Aperture Ladar. This thesis is consist of the following parts:1、The first part introduces the development of Ladar,the fundamental of ranging using linear frequency Modulation wave of Laser and the advantages and difficulties of frequency modulation in DFB laser compared to existing methods。2、The next chapter introduces the design of generating module of DFB laser with photoelectric feedback.1: Clock design of the generating system and processing system. 2: Design of pre-distorted driving voltage using FPGA+DAC. 3: Opticeletronic feedback loop circuit and the low-pass filter Design in the loop. 4: Design of reference frequency of phase detector using FPGA+DDS. 5: Design of voltage-to-current convertion circuit using OP-AMPs.3、The third chapter introduces the design of coherent and balanced laser receiver. The receivers have two types. The first type is used in the opticeletronic feedback loop and the second type is used in the module of receiving the reflected laser from the target. The two types of receivers are used in different conditions. Because the laser power and the bandwidth of beat frequency are different, so the components and circuit are different to achieve desired Signal-to-Noise ratio.4、The PCB design and layout is done to meet the requirements of low noise, mainly in the power&ground layers design and the adjustment of some key signal lines.5、A further analysis of the photoelectric feedback results obtained from the oscilloscope is done using MATLAB and the frequency-to-current curve of DFB laser has been found out. Then a design of pre-distorted triangular driving voltage using iteration is done. The choosing of the best feedback loop parameters based on the obtained experiments results is introduced too.