High precision interferometer apparatus employing a grating beamsplitter

US7414730B2 · kind B2 · utility

Assignee

• The Board of Trustees of the Leland Stanford Junior University · US

Inventors

• Ke Sun · Mercer Island, US
• Graham S. Allen · Livermore, US
• Robert L. Byer · Stanford, US

Key dates

• Filing date: May 5, 2006
• Grant date: Aug 19, 2008
• Expiry date: Jan 26, 2027

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B2290/30
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Measurement of a distance change between a reference surface and a target is provided. A substrate has a first surface facing the target and including a grating. The grating and target combine to form an optical interferometer responsive to changes in distance between the grating and the target. A second surface of the substrate coincides with the reference surface and faces away from the target. Thickness information pertaining to the substrate is combined with results from the optical interferometer to provide a measurement of distance change between reference surface and target. The substrate is preferably a rigid material having picometer level dimensional stability.