Optical position measuring device has strips of conductive material as screen against interference from electrical fields

摘要

A scale (1) is illuminated by a light source (4) and reflects the light beam back to a detector (6). The incident beam (7) passes through a window (9) and the reflected beam (7.1) through a second window (13) constructed in an electrically conductive layer (15). Strips of conductive material (20,21) are formed across these windows to act as a screen against interference from electrical fields.