Resolution improvement of one-dimensional comb-type PSD by subdivision

Implementation of a 4 by 1 comb-type Position sensitive detector (PSD) array for position sensing applications is presented. Unlike conventional application, we utilize the method of subdivision to increase the resolution of PSD beyond the feature of photosensitive area, which is presented periodically. To obtain output signal of comb-type PSD, classic grating subdivision circuit is used. Resolution of 6.25μm of comb-type PSD is achieved using optical grating array of a 50μm in pitch and signal power of 3mW. The resolution is limited by the spacing of comb-type PSD and the mismatch of position of PSD array and optical grating array.