Deformation and slope synchronous measurement device and method based on digital speckle interferometry

Abstract

The invention discloses a deformation and slope synchronous measurement device and method based on digital speckle interferometry. Light from a laser is divided into a first beam of light and a second beam of light by a beam splitter prism. The first beam of light is reflected onto an imaging target surface of a monochrome CCD camera by another beam splitter prism, thereby forming a reference optical path. The second beam of light is reflected to a surface of a measured object via a plane mirror, thereby forming a laser speckle field. The monochrome CCD camera receives the laser speckle field at the same time from two directions which are symmetric to an optical axis, so that two object optical paths are formed. By switching the on / off state of the reference optical path and the object optical path, a digital speckle interference optical path and a shear digital speckle interference optical path for synchronous measurement are formed, a speckle interference fringe phase and a shear speckle interference fringe phase are extracted, and the surface deformation and slope of the measured object are measured. The invention realizes synchronous and independent measurement of deformation and slope information of the measured object, without repeated loading and later separation. The phase shift technology is adopted, thereby improving the measurement accuracy. The dual speckle interference optical paths with adjustable measurement sensitivity and object-light sharing are constructed, so the whole structure of the system is simple and compact.

Description

technical field [0001] The invention relates to the technical field of optical measurement, in particular to a digital speckle interferometry method. Background technique [0002] Digital speckle interferometry and shearing digital speckle interferometry are two full-field, non-contact, high-precision, high-sensitivity optical measurement techniques based on laser speckle interferometry. The former is widely used in deformation measurement, vibration analysis, shape testing and defect detection on the surface of objects, while the latter can directly measure the slope of object deformation and is mainly used in the field of industrial non-destructive testing. Integrating digital speckle interferometry and shearing digital speckle interferometry to carry out simultaneous measurement research on object deformation and slope information is more convenient for solving the problem of non-destructive testing of internal defects in objects with relatively large deformation and rela...

AI Technical Summary

Problems solved by technology

[0003] At present, the simultaneous measurement methods of object deformation and slope based on digital speckle interferometry are mainly divided into three categories: the first category is multi-aperture shearing digital speckle interferometry, which needs to make special multi-aperture templates for different test objects. The system is relatively complex, and the obtained deformation and slope information are coupled with each other and are not independent; the second type is Michelson shearing digital speckle interferometry technology, the carrier frequency deformation information and slope information obtained by this technology are coupled with each other and are not independent , it is necessary to set a suitable frequency window in the frequency domain for post-separation

Although this technique is suitable for dynamic measurement of deformation and its slope information, the measurement accuracy is not high; the third category is the combination of digital speckle interferometry and shearing digital speckle interferometry, although this technology can independently obtain deformation and its slope information, but cannot achieve simultaneous measurement of deformation and its slope information

[0004] In summary, none of the existing technologies can realize the simultaneous, independent and high-precision measurement of deformation and its slope information, which seriously hinders the development and application of digital speckle interferometry technology.

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