Optical position-measuring device having reference mark graduation structures with chirp fields

US5977539A · kind A · utility

Assignee

• DR. JOHANNES HEIDENHAIN GMBH · DE

Inventors

• Wolfgang Holzapfel · Obing, DE
• Erwin Spanner · Traunstein, DE

Key dates

• Filing date: Nov 20, 1997
• Grant date: Nov 2, 1999
• Expiry date: Nov 20, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G01D5/38
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A position-measuring device for the determination of the relative position of two objects movable with respect to one another includes at least two graduation carriers connected to the movable objects on each of which, formed as chirp fields, are disposed reference mark graduation structures that serve to generate a defined signal at a known absolute position. From the scanning chirp field assigned to the scanning graduation carrier, the incident beams of a light source disposed on the illumination side and separable into at least two individual beams of differing orders of diffraction that strike at spatially separated scale chirp fields.