Semi-Transparent Silicon Strip Sensors for the Precision Alignment of Tracking Detectors

Novel semi-transparent optical position sensors (`ALMY sensors') have been developedfor the alignment monitoring systems of modern large-area tracking detectors. More than 10 sensors can be aligned along one laser beam.The thin-film amorphous silicon strip sensors provide up to 90%transmittance for red laser light combined with minimum beam distortion and a typical position resolution of 1 micrometer over a sensitive area of several square centimeters.