US 11,946,782 B2
Optical position-measuring device for suppressing disturbing higher diffraction orders
Thomas Kaelberer, Schrobenhausen (DE)
Assigned to DR. JOHANNES HEIDENHAIN GMBH, Traunreut (DE)
Filed by DR. JOHANNES HEIDENHAIN GmbH, Traunreut (DE)
Filed on Oct. 5, 2022, as Appl. No. 17/960,148.
Claims priority of application No. 10 2021 211 814.3 (DE), filed on Oct. 20, 2021.
Prior Publication US 2023/0120787 A1, Apr. 20, 2023
Int. Cl. G01D 5/347 (2006.01)
CPC G01D 5/34715 (2013.01) 20 Claims
OG exemplary drawing
 
1. An optical position-measuring device for determining a relative position of at least two scales, the optical position-measuring device comprising:
a light source configured to emit an illumination beam along a scanning beam path; and
the at least two scales, which are movable relative to each other along at least two measurement directions and disposed in different planes in crossed relation to each other, the at least two scales each having at least one measuring graduation having grating regions which are arranged periodically along at least one of the measurement directions and have different optical properties, each of the at least two scales having a direction of longitudinal extent oriented parallel to a first or a second one of the measurement directions; and
a detector configured to generate one or more position-dependent scanning signals with respect to relative movement of the scales along the first or second measurement direction,
wherein the scanning beam path is configured such that:
at the first scale, the illumination beam is split into at least two sub-beams,
the at least two sub-beams subsequently impinge on the second scale and are reflected back toward the first scale, and
the reflected-back sub-beams strike the first scale again, where the reflected-back sub-beams are recombined, so that at least one resulting signal beam subsequently propagates toward the detector,
wherein the at least one measuring graduation of at least one of the scales is configured as a two-dimensional cross grating which has a filtering effect that suppresses disturbing higher diffraction orders at the cross grating, and
wherein the cross grating has first and second areal measuring graduation regions which are arranged in a checkerboard-like pattern and have different optical properties and which are arranged periodically with a first regional periodicity along a direction of longitudinal extent of the cross grating and periodically with a second regional periodicity along a direction of transverse extent of the cross grating that is oriented orthogonally to the direction of longitudinal extent, the first and second areal measuring graduation regions having superimposed thereon a one-dimensional or two-dimensional periodic line grating.