Research On Synchronous Position Detection System Of Multi-beam Based On DSP And Position Sensitive Detector

Position sensitive detector, used to detect the position of the incident light, is asemiconductor device based on the transverse photoelectric effect. The methods ofdetecting light position based on the PSD have amplitude method and phase method,amplitude method is vulnerable to the influence of the background light, so the appliedfield of the PSD is restricted, phase method is hard to the influence of the backgroundlight and can detect the position of multiple lights, signal processing circuit of phasemethod is simple, phase method can overcome many faults. Almost there is no people tostudy the phase method, at present there is no mature signal processing circuit. Based onthe above content, this paper puts forward the multi-beam position detection system ofthe PSD phase method based on DSP.Based on Lucovusky equation and RC transmission line model, the principle ofposition detection of PSD phase method is deduced. In order to accurately measure thephase of the PSD output signal, all phase FFT (apFFT) data processing is proposed, andthe principle of apFFT has been demonstrated. Then the overall program of themulti-beam position detection system of the PSD phase method is proposed; based onthe program, software part and hardware part of the detection system are designed. Theexperimental platform of detection system is set up, the detection experiments of theOne-dimensional PSD and two-dimensional PSD are done. Last the experimental errorsare analyzed in detail, and the measures to reduce the error are proposed.Experiments show that the phase difference of the PSD output current signal hassignificant linear relationship with the position of the light, this is consistent with theresult of the theoretical derivation. Within the range allowed by the modulationfrequency, PSD conversion sensitivity is increasing with the increase of the frequencyof the modulated signal, but the linearity of the phase-position curve will decline; Theposition detection error is increasing with the increase of the distance between the pointof light and the center of PSD. At the same time, if the frequency of the modulatedsignal increases, the position detection error also increases.In this paper, the multi-beam position detection system of the PSD phase methodbased on DSP can detect the position of multiple points of light, the present study workprovides a effective solution for multi-beam position detection.