WIDEBAND OPTICAL POSITION SENSOR WITH NORMALIZATION

A novel electro-optical sensor for the wideband and normalized translation of the two-dimensional position of a light beam transverse to its traveling direction into electrical position signals. Incident on the sensor is the light beam 122 which is divided with a beamsplitter 121 into a transmitted beam 123 and a reflected beam 124 which both have similar transverse motion behavior as the incident beam. From each of these divided beams the position is determined one-dimensionally with an one-dimensional optical position sensor, 125, 126. The one-dimensional position determination is done by dissecting each divided beam into two beams using a partitioning element. The outputted dissected beams have a power distribution that depends on the position of the divided beam relative to the partitioning element. Each beam is optically coupled to a photo detector which translates its power into an electric current. In each circuit 127, 128, the two photo detectors are reverse biased and electrically connected in series. The node connecting them is a current type position output. The sum current through the two photo detectors is determined using two current mirrors. The first mirrors the current through one photo detector, the second mirrors the output current of the first current mirror plus the current through the second photo detector and outputs a current type sum signal. Each position signal is normalized with respect to its sum signal using an analog-to-digital converter, 129, 130, with the sum signal coupled to the reference input and the position signal coupled to the regular signal input.