Apparatus and method for optically measuring a surface

Patent 5311286 Issued on May 10, 1994. Estimated Expiration Date:

April 1, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3627427

Surface deformation gauging system by moire interferometry
Patent #: 3943278
Issued on: 03/09/1976
Inventor: Ramsey, Jr.

Measurement of surface roughness
Patent #: 4145140
Issued on: 03/20/1979
Inventor: Fujii

Extended-range moire contouring
Patent #: 4794550
Issued on: 12/27/1988
Inventor: Greivenkamp, Jr.

Apparatus and method for projection moire mapping Patent #: 4981360
Issued on: 01/01/1991
Inventor: Schwarz

Inventor

Pike, John N.

Assignee

Materials Technologies Corporation

Application

No. 861605 filed on 04/01/1992

US Classes:

356/605, Moire250/237G, Gratings (moire fringes)356/445OF LIGHT REFLECTION (E.G., GLASS)

Examiners

Primary: Rosenberger, Richard A.
Assistant: Pham, Hoa Q.

Attorney, Agent or Firm

McCormick, Paulding & Huber

Foreign Patent References

0206908 JP 12/12/1983
0243841 JP 10/12/1988

International Class

G01B 011/30

Abstract

An apparatus and method measures the roughness or some other surface dimension by transmitting a beam of light through a grating member at an angle of incidence relative to the grating member. The grating member has a plurality of parallel opaque bars and adjacent transparent bars. The beam of light forms a multiple line shadow pattern on the surface below the grating member formed by the shadows of the opaque bars of the grating member. A camera records the multiple line shadow pattern, and the recorded pattern is superimposed on a plurality of parallel, equally spaced scan lines oriented perpendicular to the shadow lines. The distances between the points at which adjacent shadow lines cross each respective scan line are measured to determine the roughness or some other surface dimension.

Other References

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