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Method and apparatus for extracting order value of coherent gradient sensing interference fringe

A coherent gradient sensitive and interference fringe technology, which is applied in the field of fracture mechanics parameter measurement, can solve problems such as errors, thick interference fringes, and irregular shapes, and achieve the effects of improving accuracy, improving calculation accuracy, and reducing errors

Inactive Publication Date: 2006-07-12
TSINGHUA UNIV
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Problems solved by technology

[0003] The disadvantages of the above-mentioned prior art: similar to other photometric methods for processing fringe patterns, to obtain fracture mechanics parameters, the coherent gradient-sensitive interference fringe series must be extracted first, and to determine the coherent gradient-sensitive interference fringe series must be accurately extracted Stripe Centerline
from figure 1 It can be seen that the interference fringes are thick and irregular in shape. It is difficult to meet the accuracy requirements if the fringe centerline is extracted only by image processing, and it may even bring a large error, especially for low-order fringes

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  • Method and apparatus for extracting order value of coherent gradient sensing interference fringe
  • Method and apparatus for extracting order value of coherent gradient sensing interference fringe
  • Method and apparatus for extracting order value of coherent gradient sensing interference fringe

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[0027] The method for extracting the series of coherent gradient-sensitive interference fringes proposed by the present invention first expands a beam of laser light to obtain divergent light, then becomes parallel light through a convex lens, and is incident on the surface of the test piece; the parallel light beam emitted from the test piece is divided into Two rays, the distance between the first ray and ray is Δ 1 The first grating and the second grating produce coherent gradient-sensitive interference fringes, and the second light passes through with a distance of Δ 2 The third grating and the fourth grating generate coherent gradient-sensitive interference fringes; image the two interference fringe fields and take pictures of the interference fringe fields; The background light intensity of the interference fringe pattern is a 1 、a 2 Apply load to this test piece, take the coherent gradient sensitive interference fringe figure of loading test piece from two optical pat...

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Abstract

The invention relates to a method to extract the coherent gradient sensitive interference fringe level number in fracture mechanics. Wherein, splitting the parallel light beam into two paths to generate coherent gradient sensitive interference fringe respectively; subtracting the background light intensity in two figures of coherent gradient sensitive interference fringe, calculating the fringe level number ml of the first figure. Wherein, the opposite device comprises: a laser, a beam expander, a convex lens, a semi-reflecting semi-transparent mirror, four gratings, two groups convex lens and diaphragms, and two cameras and computers. This invention can improve the calculation accuracy obviously without knowing the opposite load of fringe image.

Description

technical field [0001] The invention relates to a method and a device for extracting coherent gradient-sensitive interference fringe series and belongs to the technical field of fracture mechanics parameter measurement. Background technique [0002] Coherent Gradient Sensing (hereinafter referred to as CGS) is a non-contact, full-field transverse double-grid shearing interferometry method with online spatial filtering effect. It uses two parallel gratings to reorganize the The beam is twisted to generate interference fringes, and the relationship between the in-plane stress gradient or out-of-plane displacement gradient and the fringe progression is established through the optical interference control equation. This method can be used to study the deformation information of transparent and non-transparent objects in the case of transmission and reflection, respectively, and its fringe distribution directly reflects the in-plane stress gradient field in the case of transmissi...

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Application Information

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IPC IPC(8): G01N21/88G01J3/45G01B11/16
Inventor 姚学锋许蔚刘栋梁
Owner TSINGHUA UNIV
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