Low noise optical position sensor

摘要

A novel optical position sensor is described that uses two component photodiodes electrically connected in parallel, with opposing polarities. A lens provides optical gain and restricts the acceptance angle of the detector. The response of the device to displacements of an optical spot is similar to that of a conventional bi-cell type position sensitive detector. However, the component photodiode design enables simpler electronic amplification with inherently less electrical noise than the bi-cell. Measurements by the sensor of the pointing noise of a focused helium-neon laser as a function of frequency demonstrate high sensitivity and suitability for optical probe beam deflection experiments.