Three-axis high optical subdivision grating ruler

Abstract

A three-axis high optical subdivision grating ruler comprises a dual-frequency polarization parallel light and reference light generation module, a non-polarization beam splitter prism, a combined grating, a two-dimensional subdivision prism assembly, a two-dimensional grating, a heterodyne photoelectric conversion unit module, a light source driver and a signal detection and processor. The device is characterized in that the dual-frequency polarization parallel light and reference light generation module generates three beams of dual-frequency polarization parallel light, the three beams of dual-frequency polarization parallel light pass through the non-polarization beam splitter prism and the combined grating, then enter the two-dimensional subdivision prism assembly, are subjected to back-and-forth near Littrow angle diffraction-reflection between the two-dimensional grating and the two-dimensional subdivision prism assembly, are finally subjected to auto-collimation retroreflection, and are respectively subjected to beam combination through the combined grating; and the two-dimensional grating is reflected by the non-polarization beam splitter prism, is received by the heterodyne photoelectric conversion unit module, and is further driven by the light source and detected and processed by the signal detection and processor, so that displacement and angle measurement of optical subdivision of 8 times or more of X / Y / theta z three axes of relative movement of the two-dimensional grating are obtained.

Description

technical field [0001] The invention belongs to the field of precision optical measuring instruments, in particular to a three-axis high optical subdivision grating ruler for three-degree-of-freedom displacement and angle measurement. Background technique [0002] Dual-frequency heterodyne laser interferometers are widely used in displacement and angle measurement in precision motion tables, precision optical machinery, and precision measuring instruments, but they are easily affected by the environment such as temperature, humidity, and air pressure. The single-frequency laser interferometer developed in recent years also has corresponding problems. Grating scales are also called optical encoders. Among them, the grating scales based on high-density diffraction gratings have higher precision and resolution than those based on low-density ordinary geometric gratings, and can reach sub-nanometer levels. The well-designed high-density diffraction grating has the unique advant...

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Problems solved by technology

[0009] Chinese patent CN104613865 B proposes a prism-based high optical subdivision grating scale, which can achieve more than 8 times of optical subdivision, but it is difficult to expand to two axes and above for one axis

Cunbai Lin et al., Two-dimensional diagonal-based heterodyne grating interferometer with enhanced signal-to-noise ratio and optical subdivision, Optical Engineering, 57(6), 064102), its structure is huge, the grid line density is not high enough, and it is difficult to realize three-axis

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