Patent ID: 6856389

Claim:
A portable reflex comparator for testing the quality of a retroreflector part comprising: a housing with first and second end walls, side walls, and a handle for carrying the housing; a light source located at one end of the housing; a light modulating device spaced apart from the light source; a focal plane offset from the light modulating device; a collimating lens positioned parallel to the focal plane, wherein the collimating lens is operable to receive a diverging beam of light from the focal plane, direct said beam of light substantially normal to the surface of a reflex part, receive the light beam back from the reflex part and converge the light beam to the local plane; a signal detector for detecting a reference signal; a lock-in amplifier disposed in optical communication with said signal detector for filtering out noise; and a meter operable in electrical communication with said amplifier and operable to output a signal indicative of the part being tested.