Measurement accuracy of lateral-effect position-sensitive devices in presence of stray illumination noise

Photodetectors and position-sensitive detectors (PSDs) are widely used in environments where several other light sources also coexist. These randomly arising illumination noises may fall on the detector surface in different spatial distributions and produce unpredicted variations in the PSD output. In this paper, we first describe these stray noises with respect to the operation of PSDs. Then we study and model how the presence of the spurious sources modifies the measurement accuracy of these detectors. The experimental results obtained for the position measurement accuracy while using PSDs and signal beams along with the spurious sources are presented. The experimental data is compared with the results from the proposed mathematical model and it is seen that measured accuracy is within a fraction of a percent of the calculated one. The analysis of systematic errors encountered during data collection is also presented.