Double-pulse digital speckle transient measuring device and method

Abstract

The invention discloses a double-pulse digital speckle transient measuring device and method, belonging to the field of digital speckle interference measurement. The measuring device comprises a double-pulse laser, an optical system, a synchronous controller, an image acquisition system and a transient speckle data processor and is characterized in that the double-pulse laser and a double-exposure camera are used as a light source and a photoelectric receiving system respectively, the accurate timing of the synchronous controller controls the synchronous work of the laser and the camera, and the transient speckle data processor is used to realize the measurement of the transient vibration shape of the structure surface within the adjustable time interval. The measuring device has the advantages of non contract, high resolution, overall simultaneous measurement and accurate acquisition of the transient vibration shape of the object. In addition, the measuring device has indispensable application value in the dynamic characteristic analysis and transient measurement of the complicated structure, micro structure and thin-wall structure in the military hardware.

Description

technical field [0001] The invention relates to a digital speckle interferometry technology, in particular to a transient speckle measurement technology based on a double-pulse laser, and belongs to the field of digital speckle interferometry. Background technique [0002] Digital speckle interferometry is an optical measurement method for quantitative analysis of full-field displacement and strain. Its basic principle is to obtain mechanical information such as displacement and strain fields by comparing the changes in surface speckle patterns before and after deformation of the specimen. [0003] At present, the research on digital speckle measurement mainly focuses on the steady state, that is, static, quasi-static and out-of-plane steady-state vibration in the usual sense. The steady-state method deals with the average effect of the interference image, and cannot obtain a certain instantaneous vibration. morphology, and vibration phase information cannot be obtained. Fo...

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Problems solved by technology

[0003] At present, the research on digital speckle measurement mainly focuses on the steady state, that is, static, quasi-static and out-of-plane steady-state vibration in the usual sense. The steady-state method deals with the average effect of the interference image, and cannot obtain a certain instantaneous vibration. morphology, and vibration phase information cannot be obtained

For the digital speckle interferometry system, traditionally, a continuous laser is used as the light source and a speckle system with a low image acquisition speed. The time interval between collecting two separate speckle images is at least 20ms, which is only suitable for measuring objects that change relatively slowly. and with little external interference

In terms of transient speckle measurement, Peng Xiang et al. introduced a pulse-based The digital speckle interferometry technology of the ND:YAG laser system has designed and realized the synchronous control of the object, the pulsed laser trigger and the CCD image acquisition, but the pulse interval is only (650-800) μs, and there is a certain gap in the measurement of the tiny instantaneous shape.

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