Shearogaphy is an interferometric system that uses an expanded beam of laser light that is reflected off the specimen. This is accomplished by fringe patterns caused by differential surface deformation and the coherence of laser light when projected onto a test object.

There are two main steps in Shearography measurement.

1.	Coherent Laser light illuminates the object in which the light reflected from the object is sheared.
2.	A thermal, tensile, vibratory or pressure load is applied to the test specimen to cause it to deform. When the object is deformed, the speckle pattern is slightly modified. Comparing the two speckle patterns (stressed and unstressed) produces a fringe pattern which depicts the relative displacement of two neighboring points.

Typical discontinuities which are detectable include: Delaminations, disbonds, impact damage, voids and subsurface defects.