Grating sensor displacement measuring system based on phase modulation

Abstract

The invention discloses a grating sensor displacement measuring system based on phase modulation. The system comprises a grating sensing optical path unit and a signal processing unit. The grafting sensing optical path unit comprises a collimation light source, an MEMS scanning mirror, a main grafting and an indicating grafting. The signal processing unit comprises a photoelectric conversion device and phase-locked loop phase. The MEMS galvanometer structure is used for carrying out phase modulation on relative displacement signals of the indicating grating relative to the main grating, and precise measurement of displacement can be achieved through a single detector. By demodulating the signals by a phase-locked loop at the position of a specific harmonic frequency spectrum, measuring signals are migrated out of low frequency bands, the influences of direct current drifting and other low-frequency changes are overcome, the influences of high-frequency-band noise can be effectively reduced during signal processing, orthogonal errors caused by traditional grating sensor two-path or four-path signals are avoided, the influences of direct current drifting and amplitude fluctuation on the measuring result are reduced, and the measuring precision of the measuring system during low-speed and high-speed displacement measurement is improved.

Description

technical field

[0001] The invention relates to the field of precision displacement measurement systems, in particular to a grating sensor displacement measurement system based on phase modulation. Background technique

[0002] The grating displacement measurement sensor realizes displacement measurement according to the Moiré fringe principle, and has significant technical advantages in measurement range, measurement accuracy, response speed, etc., and is widely used in processing machine tools, measuring instruments, semiconductor processing equipment and other fields. The grating sensor uses the grating period as the basic measurement unit for displacement measurement. With the advancement of photolithography technology, the grating period is getting smaller and smaller, thus providing a more precise scale for higher precision measurement. With the increase of grating rule density, the reading of grating signal is more easily disturbed by alignment, vibration and other fa...

Images