The Research Of Light-spot Spatial Position Measurement Technology Based On PSD

Position measurement is widely used in military, industry,scientific research andother fields.The spatial position of the light-spot detection is very important in thefield of non-contact measurement. To change the shortcomings of light-spot detectionmethods now, a light-spot position measuring system based on double PSD isdesigned combined with the demand of actual measurement and the characteristic ofmeasured object in this paper.PSD is widely used in photoelectric measurementsbecause of its high response speed, simple signal processing circuit and lowrequirements of the optical system.This method is based on binocular vision,the burstpoint image in the two-dimensional PSD,the PSD capture high-speed flash signalusing its fast response characteristic, and the image point position is outputed in theform of current.the light-spot position is got by subsequent signal processing circuitand control circuit.This paper mainly includes the following aspects:1. The system overall program is designed to achieve the design features andtechnical specifications. The binocular vision measurement method isdetermined according to the demand of actual measurement.2. Photoelectric detection unit and the signal processing unit is designed toachieve spatial light spot position signal detection. the two dimensional PSDis selected as a photoelectric detector and the characteristics of the PSD isanalyzed, The parameters of the optical system is calculated and the selectionof lens is completed.According to the PSD output signal characteristics,thesignal preprocessing circuit is designed to convert the weak current signal tovoltage signal3. The system control unit and the data acquisition and processing unit aredesigned to achieve control of the entire acquisition process. ARM andCPLD-based digital control circuit is designed, Host computer and lowercomputer software programming is completed, A method for extractingeffective signal and accurate calculation for it was proposed by subtractingbackground and dark current signal. 4. Numerous outdoor experiments were did,quite satisfactory experimentalresults are obtained.The mechanical structure of the system is designed andthe experimental apparatus is built, in different outdoor background, severaltests were performed to verify the correctness of this method of subtractingbackground, at different distances, several tests were performed to verify therepeatability of measurement result. The experiments show that the linearityand accuracy of data is significantly improved by subtracting background,linearity error of the measurement at different distance can reach the range of1.2%.