International Business Machines Corporation

Darell Smith Whitaker

Michael G Lisanke

Huizong Lu

Ali Reza Taheri

Lanphuong Thi Pena

Kenneth Wayne Watts

Alan David Dorundo

Akram Aref Bou-Ghannam

Samuel Sheung-Lok So

An interferometer is used to locate and examine defects in a test surface of a test specimen. Defects are first located as the test surface is driven past the objective of the interferometer at a constant speed, with a darkfield interferogram being examined as it flows across a row of CCD elements. During this process, the location of each defect is stored. Next, the test specimen is sequentially moved into the locations at which static measurements are made using an area array of CCD elements. During these measurements, the phase angle relationship of the interferometer is varied so that heights of surface segments may be calculated. If some to these segments are located more than a quarter wave length of the interferometer light source from the surface at which the darkfield is established, a process is used to perform height corrections for segments within transition boundaries.

Apparatus and method for storing interferometric images of scanned

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Darell Smith Whitaker