Cognex Corporation

Fariborz Rostami

David J Michael

E John McGarry

John F Filhaber

Todd O Dampier

Gilbert Chiang

Feng Qian

Bill Lepior

David J Wilson

James Harald Clark

Edwin C Mangalindan

This invention provides a system and method for detecting and imaging specular surface defects on a specular surface that employs a knife-edge technique in which the camera aperture or an external device is set to form a physical knife-edge structure within the optical path that effectively blocks reflected rays from an illuminated specular surface of a predetermined degree of slope values and allows rays deflected at differing slopes to reach the vision system camera sensor. The light reflected from the flat part of the surface is mostly blocked by the knife-edge. Light reflecting from the sloped parts of the defects is mostly reflected into the entrance aperture. The illumination beam is angled with respect to the optical axis of the camera to provide the appropriate degree of incident angle with respect to the surface under inspection. The surface can be stationary or in relative motion with respect to the camera.

System and method for detecting defects on a specular surface with a vision system

A system and method for counting objects or parts on a continuously moving conveyor, or other elongated surface, provides a camera and associated machine vision system that acquire/capture and analyze multiple, successive fields of view taken within an area of interest defined by the system. Each of the fields of view includes flanking right and left overlap zones with respect to adjacent fields of view. The overlap zones are defined to be at least as wide as the maximum width of a part being counted. The captured fields of view are stored within the system and analyzed in succession based upon a set of rules. These rules determine whether or not a particular part within the subject field of view is to be counted. More specifically, the rules are applied within the overlap zones for each field of view to determine whether or not to count the part. Certain refinements to basic rules are employed to establish uncertainty regions within the overlapping zones to account for possible errors in tracking objects between fields of view.

System and method for counting parts in multiple fields of view using machine vision

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.

Low-profile image formation apparatus

The invention can be used to find the orientation of a semiconductor wafer without wafer handling, i.e., in a non-contact manner. The invention uses knowledge of the position of a semiconductor wafer, and the position of an orientation feature of the wafer, to find the orientation of the wafer. According to the invention, a curved band image is formed that includes an image of an orientation feature. The curved band image is then transformed into a straight band image. The longitudinal position of the orientation feature is then determined in the coordinate system of the straight band image, which longitudinal position is then converted into an angular displacement in the coordinate system of the curved band image to provide the orientation of the wafer.

System for finding the orientation of a wafer

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Menlo Park, CA, United States of America

Fariborz Rostami