Study On Position Sensitive Detector

Position sensitive detector (PSD) is a device utilizing the lateral photoelectric effect that produced by the non-uniform illumination of a rectifying semiconductor junction, and it can be used to detect the "center of mass" of the light incident on the surface of the device continuously. Moreover, PSD has the advantages of high resolution, fast response, simple circuitry, and the detection of intensity and position stimulatingly. These characteristics make it especially suit for the precise measurement of position, distance, displace, angle and other relevant physical variable. In this dissertation, the basic theory, construction design, fabrication, signal processing and the applications of PSD are systematic studied in order to improve the linearity.Several analytic results of one dimensional (1D) PSD under different boundary and conditions are derived based on the Lucovusky equation. The linear requirement and the response characteristic of PSD are further analyzed, as well as the main performances of PSD and the factors that dominantly affect their performance are also presented. All these studied works are the theoretical basis for designing and fabricating PSD with high performance.A comb-type 1D PSD is designed for the sake of high linearity, and its operational principle and characteristics are theoretically analyzed for the first time. As a result, a lmm*8mm comb-type 1D PSD with excellent performance, particular in the linearity is fabricated. Our experimental results show that the rms non-linearity and the typical position error are 0.1% of full length and?Sum, respectively. These results have achieved the leading level in China.According to the analysis of the non-linearity of tetra-lateral two dimensional (2D) PSD, an effective correctional method is propounded to improve the linearity. Furthermore, a signal processor suit for tetra-lateral PSD with any size based on the method above is developed. The experimental results show that after use this signal processor, the position non-linearity(rms) is less than 0.15% in the 60% range of a 13mmxl3mm active area, and the position error(rms) also reduce from?1010urn to ?0um. In the meanwhile, it has demonstrated that we have obtained the best position non-linearity results of PSD in world at the present time. The relationship between the output current and position of the modified tetra-lateral 2D PSD with orthogonal electrodes and the bordered 2D PSD with a low resistance square border on the sensitive surface are calculated, and the non-linearity distribution of two kinds PSD is also discussed. A 8mmx8mm pincushion 2D PSD is well designed for fabrication based on the Gear theorem.The finite-element method (FEM) is firstly used to study the relationship between the construction and the linearity of PSD. Based on the physical model of PSD that we have proposed, the output currents-position relationship of the bordered PSD, pincushion PSD, tetra-lateral PSD and 1D PSD are calculated. The simulated results of FEM show a good agreement with our experimental results above, and we also gain some important structural parameters for our practical application. This study offers a promise tool to simulate the PSD with more complicated construction.The noise of PSD and amplifier in practical detection are analyzed and calculated, respectively. A signal processor based on microchip with the characteristics of high precise and real time displaying is developed for 1D and 2D PSD. The signal processor is also applicable for PSD with different area and different construction.Finally, the application of PSD in level measuring is investigated, and a novel photoelectric digital level has the advantages of simple structure and high precise based on PSD is designed, which can complete both the measurement of obliquity and orientation. This novel photoelectric digital level has applied for a patent.