A Photometric-Based Method for Measuring Surface Deformation

Abstract

The invention provides a photometry based surface deformation measuring method, and belongs to the technical field of analysis and measurement. According to the method, a measured surface is fixed viaa clamp, and an initial measured surface serves as a measuring reference surface x-y; a camera is fixed towards the measured surface with the axis vertical to the reference surface; and the measuredsurface is irradiated by uniform parallel light at the depression angle of 5 to 45 degree. Under irradiation of the parallel light, a functional relation between the light intensity and gradient is obtained via calibration; reflection light intensity distribution of the measured surface before and after deformation is shot by the camera; and a displacement variation of the measured surface is calculated. The method is higher in sensitivity and sampling resolution, and can be applied to warpage measurement of a thin plate material, bearing deformation monitoring of a pressure container wall, stress concentration analysis of a bearing beam, and the like; and when a high-speed camera is used, the method can be used to measure deformation dynamically and can be applied to the fields includingdeformation process analysis and vibration analysis.

Description

technical field [0001] The invention relates to the technical field of analysis and measurement, in particular to a method for measuring surface deformation based on photometry. Background technique [0002] In recent years, non-contact measurement technology based on machine vision has been widely developed and applied. In the field of measuring object deformation, the more mature method is the machine vision speckle measurement method: the two-dimensional shape information in the speckle image is used to calculate the displacement of the speckle image before and after deformation; with the help of multi-eye vision technology, based on the principle of geometric optics, further The displacement and deformation in the direction perpendicular to the imaging plane are obtained. [0003] The speckle method has the following disadvantages: [0004] 1) Low spatial resolution of sampling - based on the principle of geometric optics, the spatial density distribution of speckle sa...

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Problems solved by technology

[0004] 1) Low spatial resolution of sampling - due to the principle of geometric optics, the spatial density distribution of speckle sampling points is limited by the speckle size and pixel resolution, so it must be down-sampled and cannot reach the pixel level;

[0005] 2) The measurement sensitivity is low - to solve the speckle spatial displacement, it is necessary to produce discernible speckle image changes, so small deformations cannot be measured;

[0006] 3) The imaging scheme is complicated and the operation is complicated - it is necessary to use multi-eye vision technology to measure the displacement and deformation perpendicular to the direction of the measured surface, and the pre-calibration and equipment operation are more complicated;

[0007] 4) Restrictions on use - limited by the complexity of the equipment, most of them are used in laboratory measurements, and it is difficult to popularize and apply them in the field of industrial testing;

[0009] 1) The cost of equipment is high - including expensive optical instruments such as interferometers;

[0010] 2) Restrictions on use - high vibration cleanliness, only used in laboratories

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