Robert R Parks

US Patent:

58974245, Apr 27, 1999

Filed:

Jul 10, 1995

Appl. No.:

8/500404

Inventors:

Christopher James Evans - Gaithersburg MD
Robert Edson Parks - Tucson AZ

Assignee:

The United States of America as represented by the Secretary of Commerce - Washington DC

International Classification:

B24B 1100

US Classification:

451 41

Abstract:

A polishing lap which is resistant to attack from corrosive and reactive ishing media and which has a surface which is sufficiently resilient to provide good finishes without hindering dimensional controlling and accuracy of the texturing comprises: a lap substrate wherein the surface of the lap substrate has an overall shape and a localized texture; and a replaceable lap film applied to the lap substrate surface and which is deformed to correspond to the localized texture of the lap substrate surface. The polishing lap can be easily reconditioned if contaminated or easily modified for use with different abrasives and polishing media.

US Patent:

57399069, Apr 14, 1998

Filed:

Jun 7, 1996

Appl. No.:

8/663021

Inventors:

Christopher James Evans - Gaithersburg MD
Robert Edson Parks - Tucson AZ

Assignee:

The United States of America as represented by the Secretary of Commerce - Washington DC

International Classification:

G01B 902

US Classification:

356357

Abstract:

An interferometric apparatus and method are provided for determining a ceal thickness and thickness variations of silicon wafers and other window-like optics. The method includes the steps of (1) emitting a beam of electromagnetic radiation having a diverging wavefront, at an object which is transparent to the radiation, (2) splitting the beam into a reference beam and a test beam, (3) positioning the object in a first position in the test beam to irradiate a central portion of the object, (4) directing the test beam through the central portion, (5) causing the reference beam to interfere with the test beam which has passed through the central portion to form a first interferometric fringe pattern, (6) changing the length of the test beam which has passed through the object until the first interferometric pattern is changed into a desired second interferometric fringe pattern, (7) determining a central thickness of the object in accordance with an amount by which the length of the test beam was changed, (8) moving the object in said test beam to a location in the test beam to irradiate a second portion of the object which is larger than the central portion, (9) causing the reference beam to interfere with the test beam which has passed through the second portion to form a third interferometric fringe pattern, and (10) determining variations relative to the central thickness in accordance with the third interferometric fringe pattern. The method can also be used for measuring thickness variations by taking into account a bow in the object. An interferometer is also provided for carrying out the method.