A two-degree-of-freedom homodyne grating interferometer displacement measurement system

Abstract

A two-degree-of-freedom homodyne grating interferometer displacement measurement system comprises a grating interferometer, a measuring grating, a preprocessing unit and a signal processing unit. The grating interferometer comprises a laser tube, a lateral displacement beam splitter prism, a polarization beam splitter prism, a quarter wave plate, a referencing grating, a refraction component and a four-channel homodyne structure. The system achieves displacement measurement based on grating diffraction, optical Doppler and homodyne signal processing. The grating interferometer outputs optical signals to the preprocessing unit, and the optical signals are converted into electric signals and transmitted to the signal processing unit. When the grating interferometer and the measuring grating do two-degree-of-freedom linear relative motion, the system can output two pieces of linear displacement. According to the two-degree-of-freedom homodyne grating interferometer displacement measurement system, a secondary diffraction principle is adopted to achieve four optical subdivisions, the sub-nanometer and even higher resolution ratio can be achieved, and the two pieces of the linear displacement can be measured. Homodyne signal processing is adopted, the influences brought by the DC component change and the amplitude change can be eliminated, and the two-degree-of-freedom homodyne grating interferometer displacement measurement system has the advantages of being insensitive to environment, high in measurement precision and the like.

Description

technical field

[0001] The invention relates to a grating measurement system, in particular to a two-degree-of-freedom homodyne grating interferometer measurement system. Background technique

[0002] In nanometer precision positioning and displacement monitoring, laser interferometry is the most widely used non-contact precision measurement technology. Heterodyne and homodyne laser interferometry are usually used. Heterodyne interferometry has the advantages of fast response, large measurement range, and strong anti-interference ability. However, due to the influence of factors such as light source, optical device adjustment error, processing error, and environment in the interferometer, the orthogonally polarized measurement light and reference light cannot be completely separated, resulting in the existence of nonlinear errors, even exceeding 10nm in large cases. And with the continuous improvement of motion indicators such as measurement accuracy, measurement distance, ...

Examples

Embodiment Construction

[0015] The structure, principle and specific implementation of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0016] Please refer to figure 1 , figure 1 It is a schematic diagram of the displacement measurement system of the first homodyne grating interferometer of the present invention. Such as figure 1 As shown, the two-degree-of-freedom homodyne grating interferometer displacement measurement system includes a grating interferometer 1, a measurement grating 2, a first preprocessing unit 3a, a second preprocessing unit 3b, and a signal processing unit 4, and the measurement grating 2 is a one-dimensional Reflective grating.

[0017] Please refer to figure 2 , figure 2 It is a schematic diagram of the internal structure of the first grating interferometer of the present invention. The grating interferometer 1 includes a laser tube 11, a first lateral displacement beamsplitter prism 12, a second lateral di...

technical field

[0001] The invention relates to a grating measurement system, in particular to a two-degree-of-freedom homodyne grating interferometer measurement system. Background technique

[0002] In nanometer precision positioning and displacement monitoring, laser interferometry is the most widely used non-contact precision measurement technology. Heterodyne and homodyne laser interferometry are usually used. Heterodyne interferometry has the advantages of fast response, large measurement range, and strong anti-interference ability. However, due to the influence of factors such as light source, optical device adjustment error, processing error, and environment in the interferometer, the orthogonally polarized measurement light and reference light cannot be completely separated, resulting in the existence of nonlinear errors, even exceeding 10nm in large cases. And with the continuous improvement of motion indicators such as measurement accuracy, measurement distance, ...

Examples

Embodiment Construction

[0015] The structure, principle and specific implementation of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0016] Please refer to figure 1 , figure 1 It is a schematic diagram of the displacement measurement system of the first homodyne grating interferometer of the present invention. Such as figure 1 As shown, the two-degree-of-freedom homodyne grating interferometer displacement measurement system includes a grating interferometer 1, a measurement grating 2, a first preprocessing unit 3a, a second preprocessing unit 3b, and a signal processing unit 4, and the measurement grating 2 is a one-dimensional Reflective grating.

[0017] Please refer to figure 2 , figure 2 It is a schematic diagram of the internal structure of the first grating interferometer of the present invention. The grating interferometer 1 includes a laser tube 11, a first lateral displacement beamsplitter prism 12, a second lateral di...

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