Interferential position-measuring device and method for operating an interferential position-measuring device

Patent metadata

Field	Value
Publication number	US-9664502-B2
Application number	US-201514729136-A
Country	US
Kind code	B2
Filing date	Jun 3, 2015
Priority date	Jun 5, 2014
Publication date	May 30, 2017
Grant date	May 30, 2017

Abstract

An interferential position-measuring device determines a position of an object which is disposed to be movable along a measurement direction. A light source is configured to emit a beam which is split into two sub-beams. One of the sub-beams impinges on an optical functional element on the object. The sub-beams are subsequently superimposed and interfered at a superposition location and a resulting signal beam propagates toward an evaluation unit configured to generate a position-dependent measurement signal from the resulting signal beam. A switching element is disposed in the signal path downstream of the superposition location and upstream of a signal-digitizing device. The switching element is configured to define a specific sampling point in time.

First claim

What is claimed is:

1. An interferential position-measuring device for determining a position of an object which is disposed to be movable along at least one measurement direction, the device comprising:
a light source configured to emit a beam which is split into at least two sub-beams, at least one of the sub-beams impinging on one or more optical functional elements on the object, the sub-beams subsequently being superimposed and interfered at a superposition location and at least one resulting signal beam propagating toward an evaluation unit configured to generate at least one position-dependent measurement signal from the at least one resulting signal beam; and
at least one switching element disposed in the signal path downstream of the superposition location and upstream of a signal-digitizing device, the at least one switching element being configured to define a specific point in time at which sampling occurs.

2. The interferential position-measuring device as recited in claim 1 , wherein the at least one switching element has a plurality of channels, each of the channels being associated with a respective one of the at least one resulting signal beam.

3. The interferential position-measuring device as recited in claim 1 , wherein the at least one switching element is disposed between the superposition location and a plurality of downstream optoelectronic detector elements and is configured to optically modulate the signal beams.

4. The interferential position-measuring device as recited in claim 3 , wherein the at least one switching element includes an optical modulator whose transmission characteristic is switchable in a temporally defined manner.

5. The interferential position-measuring device as recited in claim 3 , wherein the at least one switching element includes an optical semiconductor amplifier whose amplification characteristic is switchable in a temporally defined manner.

6. The interferential position-measuring device as recited in claim 1 , wherein the at least one switching element is disposed downstream of a plurality of optoelectronic detector elements and is configured as an electrical switching element that electrically modulates the at least one position-dependent measurement signal generated from the at least one resulting signal beam before the at least one position-dependent measurement is fed to subsequent signal-processing elements.

7. The interferential position-measuring device as recited in claim 1 , wherein the optical functional element takes the form of a measuring standard having a periodic measuring graduation which is impinged upon by at least two split sub-beams.

8. The interferential position-measuring device as recited in claim 1 , wherein the one or more optical functional elements include a reflector mirror which is disposed at a measuring arm and impinged upon by a first one of the sub-beams, while a second one of the sub-beams impinges on a further reflector mirror stationarily disposed at a reference arm.

9. The interferential position-measuring device as recited in claim 1 , wherein the light source is configured to operate in a continuous mode.

10. The interferential position-measuring device as recited in claim 1 , wherein the specific point in time at which the sampling occurs is defined solely by a point in time of switching of the at least one switching element.

11. The interferential position-measuring device as recited in claim 1 , wherein the specific point in time at which the sampling occurs is defined independent of an input frequency of the light source.

12. A method for operating an interferential position-measuring device for determining a position of an object which is disposed to be movable along at least one measurement direction, the method comprising:
emitting, by a light source, a beam which is split into at least two sub-beams, at least one of the sub-beams impinging on one or more optical functional elements on the object, the sub-beams subsequently being superimposed and interfered at a superposition location and at least one resulting signal beam propagating toward an evaluation unit configured to generate at least one position-dependent measurement signal from the at least one resulting signal beam; and
defining, by at least one switching element disposed in the signal path downstream of the superimposition location and upstream of a signal-digitizing device, a specific point in time at which sampling occurs.

13. The method as recited in claim 12 , wherein the at least one resulting signal beam is optically modulated by the at least one switching element which is disposed between the superposition location and a plurality of optoelectronic detector elements disposed downstream from the superposition location.

14. The method as recited in claim 12 , wherein the at least one position-dependent measurement signal generated from the at least one resulting signal beam is electrically modulated by the at least one switching element, which is disposed downstream of a plurality of optoelectronic detector elements, before the at least one position-dependent measurement signal is fed to subsequent signal-processing elements.

15. The method as recited in claim 12 , wherein the light source is operated in a continuous mode.

16. The method as recited in claim 12 , wherein the at least one switching element is switched on and off in a temporally defined manner by means of a clock signal.

17. The method as recited in claim 12 , wherein the at least one switching element includes a first switching element disposed between the superposition location and a plurality of optoelectronic detector elements and a second switching element disposed downstream of a plurality of optoelectronic detector elements disposed downstream from the superposition location, the at least one resulting signal beam being optically modulated by the first switching element, and the at least one position-dependent measurement signal generated from the at least one resulting signal beam being electrically modulated by the second switching element before the at least one position-dependent measurement signal is fed to subsequent signal-processing elements.

18. The method as recited in claim 12 , wherein the specific point in time at which the sampling occurs is defined solely by a switching point in time of the at least one switching element.

19. The method as recited in claim 12 , wherein the specific point in time at which the sampling occurs is defined independent of an input frequency of the light source.

Assignees

• Heidenhain Gmbh Dr Johannes

Inventors

• Meissner Markus
• Drescher Joerg
• Holzapfel Wolfgang

Classifications

• G01B9/02055

  Reduction or prevention of errors; Testing; Calibration · CPC title

• G01D5/36

  Forming the light into pulses · CPC title

• G01B9/02049

  characterised by particular mechanical design details · CPC title

• G01D5/35306

  using an interferometer arrangement · CPC title

• G01B9/02083 Primary

  characterised by particular signal processing and presentation · CPC title