Compact fiber-optic electronic laser speckle pattern shearography

摘要

Material defects and damage are detected and evaluated by stressing the material while looking for flaw-induced anomalies. In one embodiment, a thermal stressing unit is used to provide a slight temperature difference between a localized region and surrounding areas, with the change in temperature being used to reveal the defects and damage using a fringe pattern generated through the interference between two coherent laser beams. A sensor head and a head-mounted display (HMD), interfaced to a computer, power supply, and control electronics are used to measure the derivative of out-of-plane displacement with respect to an image shearing direction so as to generate a display of the fringe pattern, preferably in three dimensions through a displacement or depth map.