Contact sensing probe for a measuring apparatus

摘要

A coordinate measuring machine probe of the type including an arrangement for detecting contact with a surface, in which a light source and a plurality of photocells are arranged to generate an electrical signal upon probe pivoting motion by detection changes in light intensity sensed by the photodetectors. A summing circuit measures the total incident illumination of the photocells and controls the light source to maintain the total illumination of the photocells to be constant.