Experimental Investigation of Speckle Pattern by Laser Scribing for Digital Image Correlation

In this work, we propose an experimental investigation of speckle pattern creation techniques for strain measurements in a stainless steel plate using digital image correlation (DIC). DIC is a non-contact full-field measurement of deformations at the surface of objects. To obtain reliable and accurate measurements, the object surface must contain sufficient speckle pattern. To investigate and assess the quality of speckle patterns produced by novel laser scribing for DIC, two speckle patterns creation techniques were also compared, i.e., grinding, and spray painting with an airbrush. Laser-produced speckle patterns were generated by a programmable galvanometer scanner guiding the beam creating speckle pattern at high speed over the stainless steel plate. In this work, four appropriately scribed speckle patterns created with different laser scribing parameters were investigated. Experimental results reveal that the laser-produced speckle pattern has an accuracy of 19 nm in static error measurements with an uncertainty of 3 nm and an uncertainty of 99 nm in 5 mu m displacement measurements.