Optical system for rapid inspection of via location
AssigneeInternational Business Machines Corporation
InventorsMark R. King, William H. Vonderhaar
Life of this patent
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Abstract
An inspection system in which the surface of a substrate is continuously scanned by a linear CCD. The surface is illuminated in a narrowly focused strip from a broad-band light source that is selectively wavelength filtered to optimize image contrast to the optical characteristics of the surface under inspection. A channel integrator in the light source optical system provides illumination homogeneity at the surface of the substrate.
Claims10
An optical system for illuminating a narrow rectangular area of a surface of a part to image features of said part on a linear CCD array as said part moves relative to the narrow rectangular area and said linear CCD array, said optical system comprising in combination in an optical path:
- a broad band, non-coherent light source;
- a fiber optic bundle having an entrance pupil and an exit pupil;
- means to direct light from said broad band, non-coherent light source to said entrance pupil of said fiber optic bundle;
- means to direct light from said exit pupil of said fiber bundle to a filter having a selectable filter element that provides enhanced contrast between a via image and said surface;
- a channel integrator for providing illumination homogenization, said channel integrator having an entrance face and an exit face;
- means to image said exit pupil of said fiber bundle, passing through said selectable filter, onto the entrance face of said channel integrator;
- means including a beam splitter to image the exit face of said channel integrator onto said surface, and;
- means including said beam splitter to image light reflected from said surface on said linear CCD array.
A method for illuminating a narrow rectangular area of a surface of a part to image features of said part on a linear CCD array as said part moves relative to the narrow rectangular area and said linear CCD array, said method comprising the steps of:
- directing light from a broad band, non-coherent light source to an entrance pupil of a fiber optic bundle;
- directing light from an exit pupil of said fiber bundle to a filter having a selectable filter element that provides enhanced contrast between a via image and said surface;
- imaging an exit pupil of said fiber bundle, passing through said selectable filter element onto an entrance face of a channel integrator;
- imaging an exit face of said channel integrator onto said surface, and;
- imaging light reflected from said surface on said linear CCD array.
Dependencies are inferred from the claim text.