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Nonlinear error correction method of laser interferometer, device and interferometer applying method and device

A technology of nonlinear error and laser interferometer, applied in the field of laser interferometer

Inactive Publication Date: 2012-05-23
NAT INST OF METROLOGY CHINA
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Problems solved by technology

However, Heydemann et al. only considered the correction of the fundamental wave of the interference signal. In fact, in the interference signal, high-order harmonic components are generated due to the imperfection of optical components; Low harmonic components due to normal reflection

Method used

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  • Nonlinear error correction method of laser interferometer, device and interferometer applying method and device
  • Nonlinear error correction method of laser interferometer, device and interferometer applying method and device
  • Nonlinear error correction method of laser interferometer, device and interferometer applying method and device

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specific Embodiment approach

[0040] First establish the correction equation. Since in the direction of displacement, the two interference signals can be regarded as a function of equal period change, it can be expressed as a finite Fourier series:

[0041] u 1 = f 1 ( θ ) = a 10 + Σ m = 0 M / 4 [ a 1 ...

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Abstract

The invention discloses a nonlinear error correction method of a single frequency laser interferometer, a device and an interferometer applying the method and the device, and the method carries out nonlinear error correction on the interferometer by utilizing the harmonic separation correction method and comprises the following steps: step 1: establishing a correction equation for obtaining a phase angle of interference signals from two lines of the interference signals of the interferometer according to the correction equation; step 2: correcting fundamental wave components in the interference signals, and obtaining the initial phase angle; step 3: correcting harmonic components in the interference signals, and obtaining the corrected value of the phase angle; and step 4: obtaining the precise phase angle after compensation modification according to the initial phase angle and the corrected value of the phase angle, accordingly obtaining the displacement of a measuring mirror of the interferometer, and further realizing the nonlinear error correction of the interferometer. The method can eliminate various harmonic components causing nonlinear errors in the interference signals, and optimize the nonlinear error correction of the single frequency laser interferometer.

Description

technical field [0001] The invention relates to the technical field of laser measurement, in particular to a single-frequency laser interferometer nonlinear error correction method and device and a laser interferometer using the device. Background technique [0002] With the development of nanotechnology, microelectronics technology and MEMS, the precision requirements for size and displacement measurement are getting higher and higher. For example, Teague of the National Institute of Standards and Technology (NIST) believes that in the integrated circuit industry, when the line width will reach below 50nm in 2014, the national metrology institute should be able to guarantee the measurement accuracy of 0.4nm. The laser interferometer uses the wavelength of light waves as the basic scale, and its measurement results can be directly traced to the meter-defined wavelength reference. It is the most widely used reference measuring instrument in length measurement. The error sour...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B9/02
Inventor 高思田施玉书卢明臻杜华
Owner NAT INST OF METROLOGY CHINA
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