Shearography from a moving platform

摘要

A shearography system that operates while moving at significant speeds over a surface is disclosed. Two lasers are utilized and the distance between the two lasers is adjusted based on the altitude of the aircraft on which the shearography equipment is located, the speed of the aircraft, the distance between two lasers in the shearography equipment lasers, and the time difference between the laser pulses from each of the two lasers. The adjustment of the distance between the two lasers causes the angles of incidence and reflection to be the same for two sequential images and permits the moving shearography to work.

主权项

1. Apparatus for performing shearography from a platform that is moving at a known velocity above and over a surface, at a known distance above the surface, and the timing between pairs of coherent laser light pulses directed toward the surface from the moving platform is known, the apparatus comprising:
(a) first laser means for generating a first of the pairs of pulses of coherent light onto the surface; (b) an optical receiver positioned a known distance from the first laser means for receiving the coherent light from the first laser means that is reflected from the surface; (c) second laser means for generating a second of the pairs of pulses of coherent light onto the surface, the second laser means being spaced a known distance from the first laser means, and the second laser means being movable to change the distance between the first laser means and the second laser means, and the optical receiver receives the coherent light from the second laser means that is reflected from the surface; and (d) means for changing the distance between the first laser means and the second laser means dependent on the velocity of the moving platform, the distance of the moving platform above the surface, and the timing between the first of each pair of pulses of coherent light and the second of each pair of pulses of coherent light, the changed distance between the first laser means and the second laser means permitting the shearography to be performed.