A Laser Heterodyne Interferometry System for Angle Measurement Without Nonlinear Error

Abstract

The invention discloses a nonlinear-error-free laser heterodyne interferometer system for angle measurement, wherein the nonlinear-error-free laser heterodyne interferometer system comprises a single-frequency laser source, an acousto-optical frequency shift unit, an optical interference device, a planar mirror which moves along with the movement of a measured member, and a phase detecting device, wherein the single-frequency laser source and the acousto-optical frequency shift unit can operate for generating an incident light beam which has no frequency aliasing and has certain frequency difference and is spatially separated. Under the function of the optical interference device, the incident light beam is reflected twice by the planar mirror. Finally the reflected incident light beam is input to the phase detecting device. The yaw angle of the measured member is determined by means of change amount of the phase difference. Between generation of a measuring light beam with certain frequency difference from the acousto-optical frequency shift unit and interference, the transmission paths are separated and are spatially independent. The nonlinear-error-free laser heterodyne interferometer system prevents a periodical nonlinear error which is caused by polarized light with two frequencies in the interference optical path, thereby effectively improving measurement accuracy. The nonlinear-error-free laser heterodyne interferometer system can be widely used for geometric quantity precise measurement in the fields of numerical control machine tools, military industry, spaceflight, etc.

Description

technical field [0001] The invention relates to the field of optical technology detection, in particular to a laser heterodyne interference system for angle measurement without nonlinear error. Background technique [0002] Precision measurement of geometric quantities plays an important role in high-tech fields such as military industry, aerospace, and CNC machine tools. Especially, the measurement technology of yaw angle and pitch angle of moving guide rails has attracted more and more attention. The heterodyne laser interferometer has simple structure, strong anti-interference ability, convenient detection, and high measurement resolution can be achieved through phase comparison. It has unique advantages and wide applications in nanometer measurement. [0003] Theoretically, when the laser interferometer is working, two orthogonal linearly polarized lights with a certain frequency difference emitted by the laser source are split by the polarization beam splitter, and the ...

AI Technical Summary

Problems solved by technology

[0005] Due to this periodic nonlinear error, it is difficult to further improve the measurement accuracy of angle measurement based on heterodyne interferometry.

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