Study On Synchronous Multi-beam Detecting System Based On PSD Using Phase Method And Virtual Instrument Technology

Position Sensitive Detector(PSD) is a kind of semiconductor device that usually be used to detect the position coordinates information of light spot, which has the advantages of fast response speed, high resolution, strong anti-interference ability and so on. As we all know, position sensitive detector has many kinds of carriers that take location information, such as amplitude and phase. However, amplitude method is easily influenced by background light in application, which restricts its application scope. In contrast, the phase method is less affected by the background light, with high detection precision, needing simple signal processing circuit,which leads to broad and bright application in the field of position detection. But the study on the phase method is not ingrained, especially the signal acquisition and processing is not perfect enough, so that, a great deal of work needs to be done before being put into practice. This paper, on the basis of analysing and discussing the existing technology, puts forward and designs a Synchronous multi-beam detection system based on Position-Sensitive Detector Phase Method and Virtual instrument.At the beginning of this paper, the development and the research status at home and abroad of PSD is introduced, and the necessity of study for system based on phase method is demonstrated. After introducing the lateral photoelectric effect of PSD and two theoretical models emphatically, the principle of phase measurement is deduced. Then, three methods for measurement of phase difference are proposed and analysed comparatively. on this basis, the author has designed a LED array, the spot focusing system, signal processing circuit and virtual acquisition system, followed by system integrating and adjusting. Soon afterwards, calibrating experiments and detecting experiments are carried out based on one-dimensional PSD and two-dimensional PSD, which verify the correct of theoretical derivation. Finally, the factors which affect the detection are discussed, with system errors being classified and analysed.The final experimental results show that there is obvious linearity between phase difference of the two electrodes and light position when incident light is sinusoidal modulated. The resolving power and error increases with modulation frequency, but linearity is contrary. Thus, the research work in this paper presents a novel and reliable solution for multi-beam position detection, which offers reference resources for further research.