High resolution position encoder

摘要

The encoder has secondary coding cells (1) with diffractive holograms interfering successively with a light beam such as laser beam. The cells have the identical holograms diffracting an incident light into aligned diffraction hot spots. The holograms have a modulation to modulate a diffracted signal by orienting it at each instant perpendicular to a tangent at stripes (2, 2`, 2``) to be measured so that the collimated beam is displaced with respect to the cells. The cells have a relative position photodetector (5) oriented for corresponding to a path of the spots produced by the cells. An independent claim is also included for a method for high resolution encoding of a relative displacement of an element with respect to another element.