Optical system for use with apparatus for contouring surfaces with coherent light.

摘要

An optical system having a spherical mirror (34) is used to collect light from the surface of a turbine blade (14) or the like which is to be contoured. The spherical mirror (34) is located at an equal optical distance from both the test specimen and the linear diode array (36) so that it operates at a one-to-one magnification ratio. The linear diode array (36) is positioned behind the spherical mirror (34) and it receives light focused by the mirror and reflected by a beam splitter (32) through an opening (38) in the center of the mirror. None of the optical elements of the inspection system are located in the plane of movement of the test specimen so that even particularly long items such as a helicopter rotor blade can be contoured. Identical upper and lower optical systems allow both surfaces of the test specimen to be contoured simultaneously and each system is independently operable and oriented to prevent optical interference. An automatic gain control (40, 31, 42) is provided to adjust the optical modulator (22) so that the effective intensity of the spot presented to the diode array is maintained within predetermined limits.