Optical position measuring device

Patent metadata

Field	Value
Publication number	US-9303979-B2
Application number	US-201414483257-A
Country	US
Kind code	B2
Filing date	Sep 11, 2014
Priority date	Sep 11, 2013
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

In an optical position measuring device for detecting the relative position of a measuring standard and at least one scanning head, which are movable relative to each other in at least one measuring direction, the effective measuring point of the scanning is spaced apart from the measuring standard at a defined distance in the particular direction that has an orientation that faces away from the scanning head.

First claim

What is claimed is:

1. An optical position measuring device for detecting a relative position of a measuring standard and at least one scanning head, which are movable relative to each other in at least one measuring direction, wherein an effective measuring point of the scanning head lies at a defined distance from the measuring standard in a direction that is oriented away from the scanning head;
wherein a bundle of rays is split into two partial bundles of rays for optical scanning of the measuring standard, and each of the two partial bundles of rays impinges upon a reflection grating of the measuring standard at least once and is diffracted by the reflection grating such that a bisecting line between the partial bundle of rays incident on and reflected by the reflection grating intersects an optical axis in a point that is located on a side of the measuring standard facing away from the scanning head and represents the effective measuring point.

2. The optical position measuring device according to claim 1 , wherein:
splitting of the bundle of rays into the two partial bundles of rays takes place at least prior to impingement of the reflection grating;
in a diffraction that takes place at the reflection grating, the partial bundles of rays are deflected away from the optical axis; and
a deflection back to the optical axis takes place via at least one deflection element, where the partial bundles of rays are recombined.

3. The optical position measuring device according to claim 1 , wherein the split-up partial bundles of rays extend in symmetry with respect to the optical axis between the splitting and the recombination.

4. The optical position measuring device according to claim 1 , wherein the measuring standard is arranged as a rear surface grating and includes a plate-shaped transparent substrate and a reflection grating, having a reflective side oriented in a direction of the substrate and in a direction of the scanning head.

5. The optical position measuring device according to claim 1 , wherein the measuring standard is arranged as a front surface grating and includes a reflection grating having a reflective side oriented in a direction of the scanning head.

6. The optical position measuring device according to claim 1 , wherein:
the measuring standard is movable relative to a first scanning head along a first measuring direction; and
the measuring standard is movable relative to a second scanning head along a second measuring direction, the second measuring direction having an orientation that is orthogonal to the first measuring direction.

7. The optical position measuring device according to claim 6 , wherein the measuring standard is movable relative to a third scanning head along the first or second measuring direction.

8. The optical position measuring device according to claim 6 , wherein the measuring standard is arranged as a cross grating.

9. The optical position measuring device according to claim 1 , wherein the scanning head includes a light source, a plurality of detector elements, and a scanning plate having a splitting grating and a combination grating on one side and a plurality of additional gratings on an opposite side, so that:
a bundle of rays emitted by the light source is split up into two partial bundles of rays via the splitting grating;
the partial bundles of rays then propagate in a direction of a grating on the opposite side of the scanning plate and are thereby deflected in a direction of the optical axis,
the partial bundles of rays then propagate further in a direction of the measuring standard, where a diffraction and back-reflection in the direction of the scanning head results;
the partial bundles of rays are each deflected via further gratings in the direction of the optical axis and propagate in a direction of the combination grating on the opposite side of the scanning plate, where the partial bundles of rays are interferentially superimposed;
superimposed partial bundles of rays propagate from the combination grating in a direction of the detector elements, via which phase-shifted scanning signals are detectable.

10. A system, comprising:
a measuring standard;
at least one scanning head, the measuring standard and scanning head being movable relative to each other in at least one measuring direction; and
an optical position measuring device adapted to detect a relative position of the measuring standard and the scanning head;
wherein an effective measuring point of the scanning head lies at a defined distance from the measuring standard in a direction that is oriented away from the scanning head; and
wherein a bundle of rays is split into two partial bundles of rays for optical scanning of the measuring standard, and each of the two partial bundles of rays impinges upon a reflection grating of the measuring standard at least once and is diffracted by the reflection grating such that a bisecting line between the partial bundle of rays incident on and reflected by the reflection grating intersects an optical axis in a point that is located on a side of the measuring standard facing away from the scanning head and represents the effective measuring point.

Assignees

• Heidenhain Gmbh Dr Johannes

Inventors

• Holzapfel Wolfgang

Classifications

• G01B11/14 Primary

  for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) · CPC title

• G01D5/38 Primary

  by diffraction gratings · CPC title