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Anti-disturbance time-frequency domain wave-front detection method

A wavefront detection, time-frequency domain technology, applied in the field of optical measurement, can solve problems such as poor anti-interference ability, and achieve the effects of good anti-disturbance, light weight and simple system

Inactive Publication Date: 2012-01-25
BEIJING INSTITUTE OF TECHNOLOGYGY
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0015] The present invention proposes an anti-disturbance time-frequency domain wavefront detection method in order to understand the problem of poor anti-interference ability of decision-step phase-shifting interferometry and single-point spectrum processing method

Method used

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  • Anti-disturbance time-frequency domain wave-front detection method

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Experimental program
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Effect test

Embodiment

[0057] 1) Collect a series of interferograms

[0058] The resolution of the simulated interferogram is 128*128, and the average light intensity of the interference field I 0 =120, contrast ratio V=5 / 6, phase shift rate f 0 =20Hz, the environmental vibration is the cosine of frequency 2Hz, amplitude 0.85λ, light intensity fluctuation σ=1 caused by random noise. Sampling frequency f s =100Hz, the number of frames to collect the interferogram is 100 frames, that is, the sampling time is 1s.

[0059] with f s =100Hz sampling frequency to collect a series of interferograms and store them in the computer.

[0060] At this time, the time-series light intensity sequence obtained on any pixel point (x, y) at the same position in each interferogram is expressed by the following formula:

[0061]

[0062] At the same time, a 128*128 blank matrix A(128, 128) is established to store the calculated value of the initial phase of each pixel obtained in step 6).

[0063] 2) The light ...

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Abstract

The invention relates to an anti-disturbance time-frequency domain wave-front detection method, belongs to the field of optical measurement. The method comprises the following steps of: first, acquiring a sequence of interference patterns, and after subtracting a mean value of the sequence from a light intensity sequence of pixels at any same position in each interference pattern, performing fastFourier transform and performing broadband filtering frequency shift; then, performing the fast Fourier transform on an obtained frequency spectrum sequence; next, solving a logarithm of a result, and obtaining a phase statistical sequence of a time sequence after extracting and unwrapping an imaginary part of the result; later on, performing linear fitting on the obtained phase statistical sequence, and storing the first value of the sequence obtained after fitting in a matrix, and taking the first value as a computation value of an initial phase of a pixel; and finally, repeating the operations, after storing all computation values of the initial phases of other pixels in the matrix, and reestablishing the distribution of wave-front initial phase through airspace unwrapping. The method of the invention is simple and convenient, easy to implement, and free from the influence of environmental vibration, and has a very good anti-disturbance effect.

Description

technical field [0001] The invention relates to an anti-disturbance time-frequency domain wavefront detection method, which belongs to the field of optical measurement. Background technique [0002] Phase-shifting interferometry technology has been more and more used in the surface measurement of optical components and the measurement of system wave aberration. The principle is to introduce an orderly phase shift between the two coherent optical paths of the interferometer by certain means. During this process, the computer samples the interferogram, digitizes the light intensity and stores it in the memory, and then according to a certain mathematical model. The change in light intensity calculates the corresponding phase distribution. The light intensity distribution of the interference field formed by two coherent beams during the phase shifting process can be expressed as: [0003] [0004] Wherein (x, y) is the coordinate of any pixel in the image coordinate system...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01J9/02G01B11/24
Inventor 朱秋东郝群王明
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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