Optical position measuring arrangement

US7872762B2 · kind B2 · utility

Assignee

• DR. JOHANNES HEIDENHAIN GMBH · DE

Inventors

• Michael Hermann · Tacherting, DE
• Karsten Sändig · Palling, DE

Key dates

• Filing date: Jan 23, 2009
• Grant date: Jan 18, 2011
• Expiry date: Jul 24, 2029

Classification

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

Abstract

An arrangement for generating phase-shifted incremental signals characterizing relative positions of two objects moving with respect to each other along a measuring direction. The measuring arrangement includes a light source emitting bundles of beams, a measurement grating, a plurality of optional gratings and a scanning unit. The scanning unit includes a grating in a scanning plane, wherein the grating includes a plurality of blocks arranged periodically along the measuring direction with a grating periodicity equaling a fringe pattern periodicity, and each block includes n grating sections arranged along the measuring direction, each of the n grating sections having a periodic grating structure, deflecting the bundles of beams propagated through each of the n grating sections in several different spatial directions. The scanning unit further includes a plurality of detector elements arranged downstream of the grating, wherein the detector elements are arranged in the spatial directions in the detector plane, and wherein the detector plane is located where the bundles of beams coming from the grating are spatially separated. The fringe pattern is formed in the scanning plane by t…