High-resolution light spot localization with photodiode arrays

Abstract

We describe two analog electronic techniques to determine the position of a light spot on a linear photodiode array by detecting its intensity peak or its centroid. The position was detected with an accuracy of 1 and 3.5 μm by the two methods, respectively, using a 16-μm center-to-center array. As an example, the displacement of a mirror was measured with a sensitivity of 0.05 μm.