Method and apparatus for reducing heterodyne interference nonlinear error first harmonic component

Abstract

The invention relates to a method of reducing the heterodyne interference non-linear error first harmonic component and its equipment, the existing kinds of system and the method are all very complex. The invention includes: the light beams which contains two frequencies, two polarization directions and sends out by the double frequency laser; this light beam divides into two bunches of light after the spectroscope, the reflected light forms the reference signal after the analyzer by the photo detector receive; the transmitted light enters the polarization spectroscope to divide into two bunches of light which includes the reflected light of polarization direction vertical paper surface and parallel paper surface transmitted light, the reflected light reflects to the polarization spectroscope after the reference pyramid prism, the transmitted light after survey pyramid prism installed on the swivel table also reflects the polarization spectroscope; above two bunches of light converge in the polarization spectroscope place, and formed the survey signal by the reflector reflection after the analyzer by the photo detector; swivel table axial revolves the survey pyramid prism along the survey pyramid prism heading, swivel table anti-clockwise or clockwise axial revolves 97 degree. The invention uses to increase the heterodyne interference measuring accuracy.

Description

technical field [0001] The invention belongs to the technical field of precision measurement, in particular to a method and a device for reducing the first harmonic component of heterodyne interference nonlinear error. Background technique [0002] Laser heterodyne interferometer is widely used in ultra-precision detection and nanometer measurement due to its advantages of fast measurement speed, high measurement accuracy, strong anti-interference ability, good repeatability, and strong traceability. With the development of microelectronics, micromachines and ultra-precision machining, the requirements for displacement measurement accuracy have reached the nanometer level. However, due to the existence of nonlinear errors of laser heterodyne interferometers, the further improvement of its measurement accuracy is seriously restricted. Some methods of reducing and compensating the nonlinear error of heterodyne interference require complex electronic systems or optical systems....

AI Technical Summary

Problems solved by technology

At present, there are many methods to measure and compensate the nonlinear error of heterodyne interferometer, such as a dual-phase detection method proposed by Hou and Wilkening, which can eliminate the nonlinear error of the first harmonic; The mobile system directly measures the size of the first harmonic and the second harmonic nonlinear error and compensates; TaeBong Eom and TaeYoungChoi use a lock-in amplifier to integrate the phase signals of the reference signal and the measurement signal and perform elliptic fitting to compensate for the nonlinear error. Linearity error, the above methods can compensate nonlinear error without external reference interferometer, but require complex electronic system or optical system

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