Patent ID: 7357529

Claim:
In combination with an objective lens assembly disposed coaxially of the optical axis of an inspection device for projecting thereto an image of the illuminated surface of a workpiece spaced beneath and in registry with said assembly, a variable incidence oblique illuminator, comprising a housing secured to and surrounding said assembly, illuminating means in said housing for directing an expanding cone of illumination toward said workpiece coaxially of said optical axis, a focusing element positioned between said housing and said workpiece in the path of said cone coaxially thereof, and operative to redirect and focus said cone of illumination onto the surface of said workpiece at a predetermined angle of incidence relative to said optical axis, and means mounting said focusing element for limited movement longitudinally of said axis between said housing and said workpiece, said element being operative to decrease said angle of incidence upon approaching said housing, and to increase said angle of incidence upon approaching said workpiece.