Real-time correction method of grating interferometer alignment error

Abstract

The invention discloses a real-time correction method of a grating interferometer alignment error. A grating interferometer displacement measurement optical path, a pose deflection detection optical path, a photoelectric detection module, and an interferometer signal processing and error compensation module are comprised. The grating interferometer displacement measurement optical path is mainly composed of a laser light source, a grating, a non-polarizing beam splitter, a polarizing beam splitter and a quarter-wave plate. The pose deflection detection optical path is mainly composed of a semi-transparent and semi-reflective mirror and a focusing lens. The interferometer signal processing and error compensation module processes grating interferometer signal displacement demodulation and grating measurement error compensation. According to the invention, the symmetrical optical path and a four-quadrant detector are used to measure the deflection about the x, y, and z axes of an optical reading head with respect to the grating ruler's space pose; the real-time correction of the displacement measurement is realized through the error compensation model; finally the measurement accuracy of a grating interferometer is improved; and the method has the advantages of simple measurement and small error.

Description

technical field [0001] The invention relates to the technical field of precision measurement, in particular to a method for real-time correction of an alignment error of a grating interferometer. Background technique [0002] Grating interferometer is an effective method and technology in precision measurement technology. Compared with traditional single-frequency and dual-frequency laser interferometers, the displacement measurement benchmark of the grating interferometer is the grating pitch, and the measurement benchmark of the laser interferometer is the laser wavelength, the grating interferometer can use semiconductor laser diode as the laser light source, and the requirements for the laser light source are lower than those of the laser interferometer, which reduces the cost of the light source. Air turbulence, humidity, temperature) affect the measurement accuracy. [0003] In the grating interferometer measurement system, the alignment error between the optical read...

AI Technical Summary

Problems solved by technology

In actual use, due to installation alignment errors and guide rail straightness errors, the x-axis, y-axis and z-axis deflection errors of the optical readhead relative to the grating ruler cause the displacement measurement value calculated by the readhead based on the interference signal to correspond to the grating ruler. Displacement values ​​are inconsistent, which has a great impact on the accuracy of measurement results

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