Eastman-Kodak Company

Stanley Gross

Michael Alan Marcus

David C Wideman

Jiann-Rong Lee

Harry Wayne Harris

A method for determining a thickness of a moving material having at least two optical interfaces. A length of material is transported along a transport path through a measurement region, and is maintained at a substantially constant velocity and a predetermined flatness. A beam of light is directed toward the moving length disposed within the measurement region, and a portion of the light reflected from the optical interfaces of the moving length is collected and directed toward an interferometer apparatus. The interferometer apparatus generates an interference signal representative of the collected light and analyzes a plurality of the interference signals to determine a thickness profile of the material in the first direction.

Method for measuring material thickness profiles

The present invention relates to an apparatus and method for measuring physical properties of an object, such as thickness, group index of refraction, and distance to a surface. The apparatus includes a non-coherent light interferometer (53) and a coherent light interferometer (55) in association so as to share a variable optical path delay element (54). Thickness measurements can be made, for example, of solids, liquids, liquids moving along a horizontal plane, or liquids flowing down a plane. Thickness measurements of multiple layers can be made.

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Rochester, NY, United States of America

Stanley Gross