Photoelectric position measuring device

US6445456B2 · kind B2 · utility

Assignee

• DR. JOHANNES HEIDENHAIN GMBH · DE

Inventors

• Peter Speckbacher · Kirchweidach, DE
• Michael Allgauer · Traunreut, DE
• Georg Flatscher · Schneizlreuth, DE
• Anton Sailer · Traunstein, DE
• Walburga Kern · Traunreut, DE

Key dates

• Filing date: Dec 16, 1997
• Grant date: Sep 3, 2002
• Expiry date: Dec 16, 2017

Classification

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

Abstract

In a position measuring device, a scale is embodied as a phase grating on which several partial beams impinge and are diffracted and caused to interfere with each other in the scanning unit. The entry angle (&agr;) of the partial beams corresponds to the Littrow angle, so that the diffracted partial beams of ±1st diffraction order are diffracted at the same angle &bgr;=&agr;. The diffraction efficiency of the scale is particularly great if the flanks of the bars of the scales are at an angle of approximately 70° with respect to the measuring direction, i.e., if the bars and gaps are embodied to be trapezoidal in cross section.