High Positional Resolution Pin-Cushion Position Sensitive Detector by Deliberately Introducing Barrel Distortion

High positional resolution position sensitive detector (PSD) is strongly desired in high-precision position and angle measurement systems. However, a method that can enhance the positional resolution of most types of PSDs is promising but not reported. In this work, the barrel distortion is introduced deliberately in a two dimensional (2-D) pin-cushion PSD to enhance its positional resolution, through changing the sheet resistance ratio of photosensitive area and border resistor. This method has the effect of improving the positional resolution of PSD in the entire photosensitive area. PSDs with free of distortion and barrel distortion are fabricated and tested to verify that the resolution of PSD with barrel distortion is higher than PSD with free of distortion. Multi-layer feed-forward (MLF) neural network is used to correct position errors and improve the linearity of PSD with barrel distortion to about 0.02% of nonlinearity. Consequently, a high resolution and high linearity PSD is proposed and demonstrated using the method of barrel distortion, and corrected by MLF neural work. It’s worth noting that this method can be used to improve the positional resolution of most types of PSDs, without increasing the structure complexity, manufacturing cost and pressure on the back-end signal processing circuit.