Single-monochrome-CCD phase shift dual-wavelength interferometry method based on specific phase shift amount

A dual-wavelength interference and phase-shifting interference technology, which is applied in the field of single-black-and-white CCD phase-shifting dual-wavelength interferometry, can solve problems such as difficult guarantees, errors, and separation of single-wavelength interferograms, so as to reduce measurement and calculation time and improve the measurement system. simple effect

Inactive Publication Date: 2014-12-24
SOUTH CHINA NORMAL UNIVERSITY
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Problems solved by technology

However, there are two problems in this method. One is to use light sources close to the wavelengths of red, green, and blue. When the wavelengths of the light sources deviate from the three primary colors, or the wavelengths of the two light sources

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  • Single-monochrome-CCD phase shift dual-wavelength interferometry method based on specific phase shift amount
  • Single-monochrome-CCD phase shift dual-wavelength interferometry method based on specific phase shift amount
  • Single-monochrome-CCD phase shift dual-wavelength interferometry method based on specific phase shift amount

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Embodiment 1

[0094] In embodiment one, using figure 1 The measurement optical system and the figure 2 The flow of steps shown is carried out for experimental measurements. In the implementation, the spherical wave formed by the imaging objective lens IL is used as the objective light, and the imaging objective lens IL is a microscopic objective lens with a magnification of 25 times and a numerical aperture NA=0.40. Two laser beams with wavelengths of 532nm and 632.8nm are used in the measurement, and p=1 in formulas (2), (3) and (4). In the implementation, a two-step phase-shift algorithm is used to calculate the single-wavelength wrapping phase, so five simultaneous phase-shifted dual-wavelength interference fringe patterns are collected. Figure 3 is the collected five simultaneous phase-shifted dual-wavelength interference fringe patterns with specific phase shifts. From left to right, their phase shifts for the 532nm wavelength laser are δ 1,i =0, 2π, 2.38π, 4π, 4.76π, and the phase...

Embodiment 2

[0097] In order to further demonstrate the practicability of the method of the present invention, the second embodiment simulates an experiment in which the method of the present invention is used for three-dimensional shape measurement of a spiral phase plate. Figure 7 It is the height distribution of the spiral phase plate to be measured in this simulation experiment, and the height difference of the height jump part is 534nm.

[0098] Figure 8a to Figure 8e is the simulated dual-wavelength simultaneous phase-shift interference fringe pattern with five specific phase shifts containing the helical phase plate modulation information, where Figure 8a The phase shifts at both wavelengths of 532nm and 633nm are 0, Figure 8b and Figure 8d Indicates that at a wavelength of 532nm relative to Figure 8a The phase shifts are 2π and 4π, respectively. Figure 8c and Figure 8e Indicates that at a wavelength of 633nm relative to Figure 8a The phase shifts are 2π and 4π, respe...

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Abstract

The invention discloses a single-monochrome-CCD phase shift dual-wavelength interferometry method based on a specific phase shift amount. The method includes the steps that first, a common-path coaxial dual-wavelength interference system is constructed, the laser with the wavelength of lambda1 and the laser with the wavelength of lambda2 are made to enter the interference system, and the lasers with the two wavelengths are adjusted to form interference patterns along a totally same path; second, a single monochrome CCD is adjusted to collect parameters of the dual-wavelength interference patterns; third, the dual-wavelength phase shift interference patterns generated by the two wavelengths at the same time are collected by the single monochrome CCD; fourth, two single-wavelength phase shift interference signal patterns with the background eliminated are separated from the collected dual-wavelength phase shift interference patterns; fifth, normalization processing is performed on the two separated single-wavelength phase shift interference signal patterns; sixth, single-wavelength wrapped phase graphs at the wavelength of lambda1 and the wavelength of lambda2 are calculated; seventh, synthetic wavelength phases with the wavelength of lambda1 and the wavelength of lambda2 are calculated, and thus three-dimensional morphology information of the surface of an object to be measured is obtained. The method is simple and easy to perform.

Description

technical field [0001] The invention relates to the fields of optical interferometry and digital holographic measurement, in particular to a single-black-and-white CCD phase-shift dual-wavelength interferometry method based on a specific phase shift. Background technique [0002] Dual-wavelength interferometry is an optical interferometry technique in which two light sources of different wavelengths are used to record the interferogram of the same object, and after measuring the wrapping phase of the object at two single wavelengths, combined with the dual-wavelength phase The unwrapping technology obtains the synthetic wavelength and phase information, so as to truly reflect the three-dimensional shape of the object. Dual-wavelength interferometry technology makes up for the shortcomings of single-wavelength interferometry that cannot obtain correct results when the phase jump between adjacent points is greater than half the measurement wavelength, and expands the range of ...

Claims

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Application Information

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IPC IPC(8): G01B9/02
Inventor 吕晓旭张望平钟丽云王翰林费蕾寰
Owner SOUTH CHINA NORMAL UNIVERSITY
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