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Surface shape detection method for optical free curved surface with large offset

A detection method and technology of deviation, which are applied in the direction of using optical devices, measuring devices, instruments, etc., can solve the problem of inability to realize the detection of optical free-form surfaces with large deviations, and avoid complex three-dimensional topography, simple system structure, and easy operation. Effect

Inactive Publication Date: 2019-01-04
XIAN TECHNOLOGICAL UNIV
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Problems solved by technology

[0009] In order to overcome the problem that the existing technology cannot realize the detection of large deviation optical free-form surface, the present invention proposes a large deviation optical free-form surface detection method

Method used

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  • Surface shape detection method for optical free curved surface with large offset
  • Surface shape detection method for optical free curved surface with large offset
  • Surface shape detection method for optical free curved surface with large offset

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Embodiment

[0036] A method for measuring the shape of an optical free-form surface with a large deviation, comprising the following specific steps in sequence:

[0037] Step 1, follow figure 1 Schematic diagram of the detection device structure to build an experimental system, based on the time phase expansion method to obtain its continuous phase distribution data. The specific process is as follows:

[0038] First, the computer controls to generate a series of coded stripes with different frequencies, which are displayed on the LCD screen and irradiated onto the reference plane, and recorded by the CCD camera. The tth (t=(0,1,2,...s)) stripe pattern can be expressed as follows:

[0039] g 0 (x,y;t)=a(x,y;t)+b(x,y;t)cos[2π(f 0 +△fx)t] (12)

[0040] Among them, a is the background light intensity; b is the amplitude modulation; △f and f 0 +△f represent the specific frequency and time carrier frequency of the observed fringe pattern, respectively.

[0041] Step 2. Demodulate the ob...

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Abstract

The invention provides a surface shape detection method for an optical free curved surface with a large offset. The method comprises that under control of a computer, a series of coding strips in different frequencies are generated and irradiates the detected free curved surface, an imaging system obtains deformed stripe images after reflection by the detected free curved surface, the obtained deformed stripes are demodulated, and 3D surface shape measurement for the optical free curved surface with the large offset is realized. A Fourier transform technology is combined with a time phase expansion technology in the method. The phase is extracted from a time-domain stripe signal detected by each pixel point according to the Fourier transform technology, and wrapping phase data is obtained.The phase is expanded in the time axis independent from other pixels of each pixel, and the expanded phase is obtained. Boundaries and areas with low signal to noise ratio do not have adverse influence on sound data points, and there is no phase accumulated error. The problem of pi / 2 limit during phase unwrapping is overcome, and the method is suitable for the 3D surface shape measurement for theoptical free curved surface with the large offset.

Description

Technical field: [0001] The invention belongs to the technical field of detecting the surface shape of optical elements, and in particular relates to a method for detecting the surface shape of an optical free-form surface with a large deviation. Background technique: [0002] Compared with traditional spherical and aspheric optical elements, free-form optical elements are more and more used in various optical and optoelectronic systems because of their more design freedom and better optical performance. However, due to the complexity and variability of the optical free-form surface, the traditional spherical and aspheric detection methods cannot meet its detection requirements. Therefore, the measurement of free-form surfaces, especially the measurement of optical free-form surfaces with large deviations, has always been a hot research issue in the field of optical technology, and has not been well resolved so far. [0003] At present, many research institutions at home an...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/25
CPCG01B11/25
Inventor 刘丙才韩路田爱玲王红军朱学亮岳鑫王小娟
Owner XIAN TECHNOLOGICAL UNIV
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