Movement quantity detector

Abstract

Abstract PURPOSE:To reduce the size and weight of a detector and facilitate its adjustment, and to increase the reliability of the detector by uniting a diffraction grating and a reflecting mirror. CONSTITUTION:A diffraction and reflection type scale is used which is constituted by providing the equal-pitch diffraction grating 2 on a glass substrate 1 and forming a vapor-deposited mirror 3 on its reverse surface. Coherent light from a light source 4 is split by a polarization beam splitter 5 into two polarized light components. One transmitted light beam (b) is incident on the scale at a point A through the mirror 6 and the other light beam (a) reflected by the splitter 5 is also incident at the point A. Then those light beams are diffracted twice according to input to and output from the grating 2 and projected as diffracted light (c) in one direction. This light (c) is split by a beam splitter 10 into two light beams, which are transmitted through polarizing plates 7a and 7b while shifted in polarization direction by 45 deg. to become signals having a 90 deg. phase difference. Those are detected by photoelectric elements 9a and 9b and made into pulses by a normal method, and they are counted by a counter to find the movement quantity. The signals of the elements 9a and 9b are compared with each other to detect the moving direction of the scale.

Inventors

• 👤 Takao Inaba
• 👤 高男 稲葉

Bibliographic Details