Plasma position detector using a segmented photodiode

Abstract

A one‐dimensional position sensing device is described which produces an electrical signal proportional to the position of maximum light intensity imaged upon its light detecting element. The device uses a segmented photodiode but the position resolution is significantly better than the segment width, which is the resolution that would be obtained using a purely digital circuit. The device is also quite fast with a delay plus rise time of about 50 nsec.