Compact fiber-optic electronic laser speckle pattern shearography
AssigneeCybernet Systems Corporation
InventorXiaolu Chen
Life of this patent
Estimating the term…
Abstract
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.
Claims8
A system for detecting defects and damage in an object, comprising:
- a thermal stressing unit operative to provide a slight temperature differential between a localized region and a surrounding area of the object;
- two coherent laser beams directed toward the object, enabling the objects to interfere with one another within the localized region;
- electronic shearography optics having a field of view which includes the localized region, the optics being operative to measure the derivative of out-of-plane displacement with respect to an image shearing direction so as to generate a fringe pattern characteristic of flaw-induced anomalies;
- and
- a display device, operatively coupled to the electronic shearography optics, upon which to view the fringe pattern.
A method of detecting defects and damage in an object, comprising the steps of:
- thermally stressing a localized region of the object;
- directing two coherent laser beams directed toward the object while it is thermally stressed, such that the beams interfere with one another within the localized region;
- viewing the localized region through electronic shearography optics to measure the derivative of out-of-plane displacement with respect to an image shearing direction so as to generate a fringe pattern characteristic of flaw-induced anomalies;
- and
- viewing the fringe pattern on a display device.
Dependencies are inferred from the claim text.