Laser-Light Speckle Formation for Deflection-Shape Identification Using Digital Image Correlation

date: 03.05.2021

category: Sporočila za javnost


The application of a speckle pattern to the surface of a structure is usually required for Digital Image Correlation (DIC)-based displacement identification. A speckle pattern generally requires the modification (e.g., painting) of the structure's surface. 

A laser-light speckle pattern is formed by laser-light interference because of the surface roughness and the laser illumination, leaving the surface of the object untouched. The interference phenomena caused by the light reflecting from the rough surface creates bright spots that move with the observed structure. The size of the speckles depends on the surface roughness, the experimental setup and the optical system. Due to physical reasons, the possible measured surface area has been relatively small (ca. 10mm x 10m); however, the researchers form the Faculty of Mechanical Engineering introduced a new method which significantly increases the measurement area (ca. 25cm x 25cm). The proposed method is researched using three experimental cases: two rigid-body motion measurements and a full-field operating-deflection-shape measurement. 

The experiments show that motion can be identified even when the amplitudes of the oscillation are as low as 0.1 µm (on a scale of 1/1000 of a pixel).

The published paper is accessible at:

slavič eng


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