A Synthetic Wavelength Phase Extraction Method Based on Circular Carrier Frequency Moire Fringe Theory
A technology of synthetic wavelength and phase extraction, which is applied in the field of optical measurement, can solve the problem of difficult separation of aspheric fringe components, and achieve the effects of reducing processing difficulty, expanding detection range, and improving accuracy
Inactive Publication Date: 2019-02-05
NANJING UNIV OF SCI & TECH
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[0005] The purpose of the present invention is to provide a synthetic wavelength phase extraction method based on the theory of circular carrier frequency moiré fringes, and at the same time solve the problem that the single wavelength detection aspheric fringes are too dense and the components are difficult to separate when directly processing circular carrier frequency moiré fringes
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Embodiment 1
[0046] The first step: use a 100mm aperture dual-wavelength Fizeau interferometer to test the aspheric surface, and the working wavelength of the interferometer is λ 1 =632.8nm and λ 2 =532nm, adjust the axial position of the test mirror to obtain the circular carrier frequency Moire fringe pattern after the superposition of two wavelength interference fringes;
[0047] Step 2: Control the output voltage of the interferometer phase shifter to achieve the synthesis wavelength λ eq =3.339μm π / 2 adopts the phase shifting step amount to shift the phase, and uses the CCD set to obtain a group of 4 frames of double-wavelength circular carrier frequency Moire fringe interferograms with the phase shifting step amount of π / 2, and the dual-wavelength circular The carrier frequency Moire fringe interferogram is as follows: figure 2 shown;
[0048] Step 3: Use the average method to remove the DC component of the acquired dual-wavelength circular carrier frequency Moire fringe interfer...
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The invention discloses a synthetic wavelength phase extracting method based on a circular carrier frequency Moire fringe theory. On the condition that an aspheric surface is tested by means of a double-wavelength interference testing device based on the Moire fringe theory, a circular carrier frequency Moire fringe graph after overlapping of two wavelength interference fringes can be obtained, and a method for directly extracting the synthetic wavelength phase from a circular carrier frequency Moire fringe graph is presented. Through performing phase shifting through using pi / 2 of the synthetic wavelength as a phase shifting stepping amount, DC component eliminating is performed on a circular carrier frequency Moire fringe phase shifting interferogram, and then squaring is performed. Furthermore secondary polar coordinate transformation is performed for obtaining a linear carrier frequency Moire fringe graph. According to a carrier frequency overlapping reconstruction theory, extraction of a low-frequency synthetic wavelength component in a frequency spectrum domain is realized, and finally a synthetic wavelength phase is extracted. The synthetic wavelength phase extracting method settles a problem of incapability of recovering the phase on the condition of overhigh fringe density in single-wavelength detection.
Description
technical field [0001] The invention belongs to the technical field of optical measurement, in particular to a synthetic wavelength phase extraction method based on circular carrier frequency Moiré fringe theory. Background technique [0002] Phase-shifting interference detection has the advantages of high precision, non-contact and high degree of automation, so it has a wide range of applications in the testing of optical element surface shape, optical system performance and optical material characteristics. Traditional phase-shifting interferometric detection uses a single-wavelength laser light source, and its test range is limited by its operating wavelength. Therefore, when detecting a large gradient surface such as an aspheric surface, the interference fringes will be too dense, making it impossible to demodulate the phase. [0003] In order to solve the above problems, the following methods are usually adopted: first, improving the resolution of the detector can make ...
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IPC IPC(8): G01B11/25
Inventor 高志山成金龙王凯亮王伟王帅袁群窦建泰朱丹
Owner NANJING UNIV OF SCI & TECH