Design And Implementation Of The Short And Medium Range High-precision Laser Phase Ranging System

Laser ranging technology has the advantages of high precision,high resolution,good anti-interference,good directionality.It is widely used in industrial automation,traffic control,environmental monitoring and reconnaissance.for great convenience.However,the sampling frequency of the existing laser ranging instruments in China is relatively high,and the degree of integration and digitization of the circuit processing part is relatively low,so it is difficult to ensure the high-precision measurement of the target.In view of the above problems,starting from the principle of laser ranging and its key technologies,this essay adopts the phase method to calculate the measured distance,and designs and implements a set of laser ranging system with short and medium range,high precision and high integration.First,this essay studies the key technologies in phase-based laser ranging,and uses the difference-frequency phase detection technology to solve the difficult problem of high-frequency signals and improve the resolution of phase measurement.In terms of data processing,the principles of the cross-correlation detection method and the spectral analysis method with high phase estimation accuracy are analyzed,and the errors generated by the three phase estimation methods are simulated and analyzed when the signal-to-noise ratio is the same.All-Phase Fast Fourier Transform(ap FFT)is used as the phase estimation method of the system.Secondly,focus on lasers and photodetectors of the core devices in the laser ranging system,and analyze their main working principles,characteristics,key performance parameters,and give the selection of laser diodes and photodetectors in this system.Then design the software and hardware circuit after completing the overall scheme design of the system.The design of hardware circuits mainly includes the laser drive,photoelectric receiver,Avalanche Photo Diode(APD)bias voltage,voltage conversion,clock generation,and master control.The signal source of the system adopts the phase locked loop(PLL)synthesis technology to output the main oscillator signal and the local oscillator signal with a frequency difference of 5KHz,which are respectively used for laser modulation and APD electrical heterodyne mixing.The software mainly includes the main program,clock generator parameter configuration,A/D conversion and other program design,to carry out function control of the system and calculation of measurement results.Finally,build the system experimental test platform,complete the hardware test of each circuit module and the whole system,and prove that the key output signals of the system meet the design requirements.By changing the distance between the system and the measurement target to test the ranging ability of the system.The test results prove that the system can measure the accuracy of millimeters in short distance measurement.In addition,the whole system is highly integrated for the length of the circuit board is 4.2cm,the width is 2.4cm,and the overall weight is 109.85 g.It has the characteristics of small size,light weight and high integration.