Grating angle magnification enhanced angular sensor and scanner

US7599074B2 · kind B2 · utility

Assignee

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

Inventors

• Ke Sun · Mercer Island, US
• Robert L. Byer · Stanford, US

Key dates

• Filing date: Jun 19, 2007
• Grant date: Oct 6, 2009
• Expiry date: Jun 6, 2028

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B11/26
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An angular magnification effect of diffraction is exploited to provide improved sensing and scanning. This effect is most pronounced for a normal or near-normal incidence angle in combination with a grazing diffraction angle, so such configurations are preferred. Angular sensitivity can be further enhanced because the width of the diffracted beam can be substantially less than the width of the incident beam. Normal incidence configurations with two symmetric diffracted beams are preferred, since rotation and vertical displacement can be readily distinguished. Increased sensitivity to vertical displacement can be provided by incorporating an interferometer into the measurement system. Quad cell detectors can be employed to provide sensitivity to rotation about the grating surface normal. A 2-D grating can be employed to provide sensitivity to angular displacements in two different planes (e.g., pitch and yaw). Combined systems can provide sensitivity to vertical displacement and to all three angular degrees of freedom.