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Browse Prior Art Database

Adjustable Radius Spherical Reference for Surface Measuring Interferometer

IP.com Disclosure Number: IPCOM000088932D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Luecke, FS: AUTHOR [+2]

Abstract

Carriage 10, which carries a converging lens 12 and mirror 14 for light from laser 16, by being adjustably moveable in directions A provides an adjustable radius, spherical wave front for accurately measuring the radius on a surface 18a of a fixed subject 18.

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Adjustable Radius Spherical Reference for Surface Measuring Interferometer

Carriage 10, which carries a converging lens 12 and mirror 14 for light from laser 16, by being adjustably moveable in directions A provides an adjustable radius, spherical wave front for accurately measuring the radius on a surface 18a of a fixed subject 18.

An expanded collimated beam of light from laser 16 enters lens 12 and emerges as a converging beam, which is divided by beam splitter mirror 20 which is fixed in position. Part of the beam is reflected by beam splitter 20, and impinges on the subject surface 18a and is reflected. The remainder of the beam from lens 12 strikes mirror 14, located at the focal point of lens 12, and is reflected. The two reflected beams recombine at beam splitter 20 and proceed to the microscope B or other optical observation system. The combination of the two beams creates an interference pattern which contains information about the surface contour of the subject surface 18a.

By moving carriage 10 and thereby moving lens 12 and mirror 14 in directions A, the radius of the spherical wave fronts reflected from mirror 14 and thus reflected from splitter 20 can be adjusted to best match the radius of subject surface 18a. This produces an interference pattern with the minimum number of fringes. The average radius of subject surface 18a is then measured as the difference in distances of the subject 18 and mirror 14 from the center point of beam splitter 20. Th...