Cognex Corporation

Bill Lepior

E John McGarry

Gilbert Chiang

Fariborz Rostami

An apparatus is provided for forming an image of the periphery of an object with a camera having optics disposed at a working distance that is significantly less than the focal length of the optics, without introducing image distortion. The invention provides an image formation apparatus having a reduced effective profile height by exploiting a folded optical path to provide reduced working distance between a camera and an object of interest, such as a semiconductor wafer, as compared with direct viewing of the object. In a preferred embodiment, the invention includes two reflecting substrates, a first reflecting substrate and a second reflecting substrate. The distance between the first and second reflecting substrates determines the number of times the light rays that form the image will bounce therebetween, and consequently, the number of images of an object periphery that will appear in the field of view (FOV) of the camera. The invention provides an image formation system that can operate within the small or narrow enclosures of some existing wafer fabrication equipment. The invention also provides reduced camera vibration.

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Castro Valley, CA, United States of America

Bill Lepior