Research On Laser Positioning Technology Based On Quadrant Detector

The laser positioning technology is a set of optical,mechanical and electrical integration spot displacement measurement technology,with its advantages of high accuracy,high repeatability,no contact and no damage has been widely used in the fields of laser radar,laser communication,biomedical and other fields of particle manipulation.In this project,we use the receiver of the four quadrant detector(Four-quadrant detector,QD)in the laser positioning system with high frame rate and high resolution,and study the laser location technology based on quadrant detector.The main contents are as follows:1,we studied the basic principle of quadrant detector,photovoltaic effect,quadrant detector principle and quadrant detector laser positioning system,and gave the block diagram of quadrant detector laser positioning system,which laid a good foundation for further research.2.The hardware circuit of the laser positioning system of the quadrant detector is designed.The design of signal amplifying and collecting circuit and FPGA data processing circuit are introduced in detail.The signal amplification and acquisition circuit is used to transform the photocurrent signal sent from the four quadrant detector to the voltage signal.The amplified analog voltage signal is converted to digital signal and sent to the FPGA data processing circuit for further processing.The FPGA data processing circuit is used to process the digital signals after AD conversion,complete the digital correlation demodulation and the spot position calculation,and send the calculated location information to PC.3.The laser positioning algorithm based on the quadrant detector,including the uniform distribution approximation method and the Gauss distribution approximation method,is introduced.The approximate expression of the algorithm is given.With the location away from the detector,the positioning accuracy of laser gradually decreases.In order to improve the accuracy of laser location,a linear interpolation algorithm is proposed.The maximum error within the full detection range is less than 0.2um in the range of 750 um square.Then the hardware circuit of the last chapter is designed,including the AD collection program design and the database storage program design.4.The influence of spot size,dark area and background light on the positioning accuracy of quadrant detector is analyzed.A laser positioning experimental platform is set up to test the resolution and location accuracy of laser positioning.