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Real-time phase shifting method for high signal-to-noise ratio speckle interferometry

A speckle interference and phase shift method technology, applied in the field of photoelectric detection, can solve the problem of speckle interference being difficult to achieve real-time, reducing effectiveness, etc., and achieve the effect of high signal-to-noise ratio and high real-time phase detection.

Active Publication Date: 2012-08-22
SHANGHAI UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Although the introduction of the phase-shift method greatly simplifies the quantitative analysis of speckle interference, and improves the measurement accuracy of the method and the signal-to-noise ratio of the obtained results, however, during the operation of the phase-shift method, at least It is necessary to extract more than three fringe images, coupled with the time limit of the mechanical movement of the phase shifter itself, it is difficult to achieve real-time performance of the speckle interference by introducing the phase shift method, which greatly reduces the effectiveness of the practical application of the method

Method used

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  • Real-time phase shifting method for high signal-to-noise ratio speckle interferometry
  • Real-time phase shifting method for high signal-to-noise ratio speckle interferometry

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Experimental program
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Effect test

Embodiment 1

[0043] Embodiment one : see figure 1 and figure 2 , which is a real-time phase-shifting method for speckle interference with high signal-to-noise ratio, the specific operation steps are as follows:

[0044] (1) At the initial moment, collect four speckle images for the measured object, and they are sequentially spaced by Phase shift amount, save the four speckle phase shift images;

[0045](2) During the measurement, the piezoelectric phase shifter is used to continuously interval at a given frequency The amount of phase shift, and real-time collection of the current speckle pattern of the measured object after prime;

[0046] (3) Perform arithmetic operations on the speckle pattern collected at the current moment, the three speckle patterns collected at the latest moment, and the four speckle phase shift images saved at the initial moment to calculate the speckle phase shift fringe pattern at the current moment;

[0047] (4) In order to improve the signal-to-noise ra...

Embodiment 2

[0050] Embodiment two : the present embodiment is basically the same as example one, and the special features are as follows:

[0051] (1) In step 1, at the initial moment, four speckle images are collected for the object to be measured, with intervals of The amount of phase shift, they are expressed as follows:

[0052]

[0053] in, are the spatial coordinates of the image, are the four speckle images collected at the initial moment, which in turn have phase shift, , represent background and amplitude, respectively, is the speckle phase at the initial instant, which is usually random speckle noise.

[0054] (2) During the measurement in step 2, the phase shifter sends is the cycle, and the interval is phase shift amount, and synchronously collect the speckle image of the measured object, the first collected at the current moment A speckle image, stored as:

[0055]

[0056] in, Indicates the phase change of the current moment relative to the init...

Embodiment 3

[0071] Embodiment 3: The shear electron speckle is used to measure the deformation of a disk fixed at the periphery under normal concentrated load at its center. According to the measurement method provided above, the detection process is:

[0072] 1) Put the fixed disk in the light path of shear speckle interference.

[0073] 2) Before starting to exert force on the disc, first use the camera to collect four pictures with intervals in turn The phase shift amount cuts the speckle phase shift map and saves it. image 3 Four sheared speckle phase shift images are saved.

[0074] 3) By applying a normal load at the center of the back of the disk, the disk is deformed, and the sheared speckle pattern after deformation is collected by a camera, Figure 4 is the acquired real-time sheared speckle image after deformation.

[0075] 4), the piezoelectric phase shifter always produces a gap Phase shift amount, real-time acquisition of the deformed speckle image ( figure 2 ). W...

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Abstract

The invention relates to a real-time phase shifting method for high signal-to-noise ratio speckle interferometry. The method utilizes a piezoelectric phase shifter to generate multistep phase shifting, a video camera simultaneously acquires a plurality of phase shifting speckle images, a phase shifting image of a speckle interference fringe is calculated through a special image acquisition serial design and a quick algorithm, comprises the phase information which represents the object deformation at the current moment, and can be demodulated through the phase. Through the special image acquisition serial design and the quick algorithm, the camera with the image acquisition speed of 20 frame / second is taken as an example, the method can complete from original image acquisition to the calculation and display of the phase shifting image within 100-150 millisecond, so the phase shifting calculation speed is greatly increased; and compared with the traditional speckle interferometry phase shifting method, the method can better suppress speckle noise, obviously improve the image contrast, and realize real-time phase extraction.

Description

Technical field [0001] The invention involves a real -time phase displacement method for dispersion interference, which is the field of photoelectric testing. Background technique [0002] Disposter interference measurement technology (ESPI) has become an important method for the metamorphic field measurement in the past two decades.Disposal interference is a new measurement method developed on the basis of holographic interference surgery and the number of displacement guidance developed. Because it has the characteristics of the audience, simple light roads, convenient adjustment, low environmental requirements, etc.Widely used in various interference measurements. [0003] The traditional scattered spots interference method usually gives measurement results by interferery stripes. Due to the influence of scattered noise, its signal -to -noise ratio is very poor.For example, determine the central line of stripes to set up work for stripes.The introduction of the phase movement ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/16
Inventor 张东升李凯
Owner SHANGHAI UNIV
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