Contactless length and speed measurement of illuminated object - using transmission regions of 2 regions with associated photo receivers to determine relative shifts

摘要

Measuring appts. is for contactless length and/or speed measurement of an illuminated or luminous object with natural surface irregularities. It counteracts disturbing ambient conditions. The optical pattern caused by the surface irregularities is formed in the similarly limited transmission regions of two apertures. The light passing through each aperture is received by an associated photo receiver. The difference between the receiver output signals is processed to determine the relative shift or speed between object and device perpendicular to the optical axis. The transmission region of one aperture has stationary raster lines perpendicular to the direction of motion. An opening forms the transmission region of the other aperture.