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US 3,943,278 AGranted
Surface deformation gauging system by moire interferometry
AssigneeStanford Research Institute
InventorStevens David Ramsey, Jr.
Life of this patent
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AssigneeStanford Research Institute
InventorStevens David Ramsey, Jr.
Estimating the term…
A technique for comparing master parts with replicas to determine differences in shapes or sizes, is disclosed, which uses interferometric techniques as disclosed. A television camera is used to scan the pattern established by illuminating the subject with a set of optical fringes. An objective lens images these on a transmission line grating. A television camera scans the transmission grating. The spatial frequencies of the subject fringes and of the grating are especially selected so that the camera can not resolve either of them but can resolve their difference. As a result, the output signals of the camera represent a contour map of the object placed on a low frequency spatial carrier, but yet, the measurement sensitivity is still determined by the spatial frequency of the subject fringes.
In a system for comparing interference patterns of two objects by comparing the interference pattern signals representative of a first object derived from a television camera used for viewing said object, with the interference pattern signals representative of a second object derived from said television camera when viewing said second object the improvement comprising
Apparatus for measuring small dimensional changes in an object by interferometry comprising
Dependencies are inferred from the claim text.