Interferential position measuring device

• US 5,428,445 A
• Filed: 05/18/1992
• Issued: 06/27/1995
• Est. Priority Date: 05/18/1991
• Status: Expired due to Term

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr. Johannes Heidenhain GmbH
• Inventors: Holzapfel, Wolfgang
• Primary Examiner(s): Housel, James C.
• Assistant Examiner(s): Le, Long V.
• Application Number:
  US07/884,793
• Time in Patent Office: 1,135 Days
• Field of Search: 356/354, 356/356, 356/400, 356/401, 250/237 G, 250/231.13, 250/231.14, 250/231.16
• US Class Current: 356/499
• CPC Class Codes: G01D 5/366 Particular pulse shapes
• CPC Class Codes: G01D 5/38 by diffraction gratings

Abstract

The invention relates to an interference device having a light source, detectors, and at least two diffraction elements with identical or only slightly different diffraction structures, wherein the parameters of the diffraction structures of the diffraction elements vary continuously as a function of location.

Claims

1. An interference device for generating signals, comprising:

a light source;

at least two diffraction elements with identical or different diffraction structures; and

detectors for detecting diffracted, mutually interfering fractional beams, wherein each of the diffraction structures of the diffraction elements has a scale period d=d(x) that varies continuously as a function of x, a direction of graduation of the diffraction element.

2. The interference device of claim 1, wherein said diffraction elements comprise diffraction gratings wherein each grating has a respective grating constant.

3. The interference device of claim 2, wherein said grating constants of the diffraction gratings are different and vary continuously as a function of x, the direction of graduation.

4. The interference device of claim 2, wherein said diffraction gratings comprise concentric circles, whose radial spacings are different and vary continuously as a function of a radial direction of graduation.

5. The interference device of claim 2, wherein the diffraction gratings have a field height that varies as a function of x, the direction of graduation of the diffraction element.

6. The interference device of claim 2, wherein the diffraction gratings have a field width that varies as a function of x, the direction of graduation of the diffraction element.

7. The interference device of claim 2, wherein the diffraction gratings have a field length that varies as a function of x, the direction of graduation of the diffraction element.

8. The interference device of claim 2, wherein the diffraction gratings transmit light from the source of light having a signal shape that varies as a function of x, the direction of graduation of the diffraction element.

9. The interference device of claim 2, wherein the diffraction gratings absorb light from said light source as a function of x, the direction of graduation of the diffraction element.

10. The interference device of claim 2, wherein the diffraction gratings have one or more fields each having a shape that varies as a function of x, the direction of graduation of the diffraction element.

11. The interference device of claim 2, wherein the diffraction gratings comprise chirped gratings.

12. The interference device of claim 1, comprising an additional, periodic grating scale graduation.

13. The interference device of claim 1, wherein said light source generates incoherent light.

14. The interference device of claim 13, wherein said light source is a light-emitting diode.

15. The interference device of claim 1, wherein said diffracting structures comprise a continuous succession of single diffracting elements, which are embodied in the form of circular disks.

16. The interference device of claim 1, wherein said diffraction elements comprise diffraction gratings having a superlattice.

17. The interference device of claim 16, wherein said superlattice comprises more than one grid field per local grid constant.

18. The interference device of claim 1, wherein said diffraction structure comprises a radial graduation.

19. The interference device of claim 12, wherein said diffraction structure comprises a radial graduation.

20. The device of claim 1, wherein said diffraction elements comprise phase gratings.

21. The device of claim 1, wherein said diffraction gratings comprise amplitude gratings.

22. The device of claim 2, wherein one of said diffraction gratings has one-half the grating constant of the corresponding diffraction grating.

23. The interference device of claim 1, wherein said detector is embodied as a structured diffraction element.

24. The interference device of claim 1, comprising a transmission grating and a reflection grating.

25. The interference device of claim 1, comprising two transmission gratings.

26. An interference device for generating signals, comprising:

a light source;

a single diffraction element having a diffraction structure to produce mutually interfering fractional beams, and wherein said diffraction structure has a scale period d=d(x) that varies continuously as a function of x, a direction of graduation of the diffraction element.

27. The interference device of claim 26, wherein said single diffraction element comprises a reflection grating.

28. The interference device of claim 27, comprising a projection lens, and a structured detector.

29. A zero sensor, comprising:

a light source;

at least two diffraction elements with identical or different diffraction structures; and

detectors for detecting diffracted, mutually interfering fractional beams, wherein each of the diffraction structures of the diffraction elements has a scale period d=d(x) that varies continuously as a function of x, a direction of graduation of the diffraction element.