Optical arrangement for symmetrizing the radiation of two-dimensional arrays of laser diodes

• US 6,683,727 B1
• Filed: 08/24/2001
• Issued: 01/27/2004
• Est. Priority Date: 03/31/1999
• Status: Expired due to Fees

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Göring, Rolf, Schreiber, Peter, Possner, Torsten
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): THOMAS, BRANDI N
• Application Number:
  US09/926,076
• Time in Patent Office: 886 Days
• Field of Search: 359/639, 359/623, 359/626, 359/627, 359/710
• US Class Current: 359/639
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 27/09 Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005
• CPC Class Codes: G02B 27/0966 Cylindrical lenses cylindrical lenses per se G02B3/06
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

An optical arrangement for symmetrizing beams which includes a plurality of laser diodes arranged next to one another. The plurality of laser diodes emit beams which are asymmetrical relative to a first direction and a second direction, with the second direction being perpendicular to the first direction. A microcylinder lens optics is arranged in an inclined manner around an optical axis. The beams emitted by the laser diodes in the first direction are collimated and deflected at different angles and are separated thereby. A direction element is arranged downstream of the microcylinder lens optics. The direction element deflects a beam of each individual laser diode in the second direction, whereby each of these beams is deflected by a different angle in the second direction, in such a way that central points of the individual beams converge at a predetermined distance in the second direction. The direction element deflects a beam of the individual laser diode in the first direction in such a way that each of these beams converges at a predetermined distance in the first direction. A redirection element is arranged at a predetermined distance downstream of the direction element. The redirection element compensates for different angles of deflection of the beams which are transmitted through the direction element in a plane.

Claims

1. An optical arrangement for symmetrizing beams comprising:

a plurality of laser diodes arranged adjacent to one another;

the plurality of laser diodes emitting beams which are asymmetrical relative to a first direction and a second direction, the second direction being perpendicular to the first direction;

a microcylinder lens optics arranged in an inclined manner about an optical axis, whereby the beams emitted by the laser diodes in the first direction are collimated and deflected with different angles to be separated;

a direction element arranged downstream of the microcylinder lens optics, the direction element deflecting a beam of each individual laser diode in the second direction, whereby each of the beams is deflected at a different angle in the second direction, so that central points of the individual beams converge at a predetermined distance in the second direction, the direction element deflecting a beam of each individual laser diode in the first direction such that each of the beams converges at a predetermined distance in the first direction; and

a redirection element arranged at a predetermined distance downstream of the direction element,

wherein the redirection element compensates for different angles of deflection of the beams which are transmitted through the direction element in a plane.

2. The arrangement of claim 1, wherein the plurality of laser diodes are arranged at least one of one above the other and on a common plane.

3. The arrangement of claim 1, wherein the plurality of laser diodes are arranged in a fixed location.

4. The arrangement of claim 1, wherein the plurality of laser diodes are arranged to form a laser diode stack.

5. The arrangement of claim 1, wherein the optical axis corresponds to an assigned linear array of laser diodes.

6. The arrangement of claim 1, wherein the microcylinder lens optics comprises a plurality of microcylinder lenses.

7. The arrangement of claim 1, wherein the microcylinder lens optics has sufficient isoplanacy.

8. The arrangement of claim 1, wherein the redirection element compensates for different angles of deflection of the beams transmitted through the direction element in a plane defined by the second direction and the optical axis.

9. The arrangement of claim 1, wherein the first direction defines an “

y”

axis, wherein the second direction defines a “

x”

axis, and wherein the optical axis defines a “

z”

axis.

10. The arrangement of claim 9, wherein the redirection element compensates for different angles of deflection of the beams which are transmitted through the direction element in a plane defined by an x-z plane.

11. The arrangement of claim 1, further comprising at least one projection lens arranged between the direction element and the redirection element, whereby the at least one projection lens directs the beams deflected in the second direction to a common focal spot.

12. The arrangement of claim 11, further comprising at least one optical fiber arranged at the common focal spot.

13. The arrangement of claim 12, wherein the at least one optical fiber comprises one of a plurality of optical fibers and a fiber bundle.

14. The arrangement of claim 1, wherein the microcylinder lens optics comprises a plurality of microcylinder lenses, at least one of the plurality comprising one of a gradient optical microcylinder lens, a spherical microcylinder lens, a aspherical microcylinder lens, and a Fresnel lens.

15. The arrangement of claim 1, wherein the microcylinder lens optics comprises a plurality of microcylinder lenses, each the plurality comprising at least one of a gradient optical microcylinder lens, a spherical microcylinder lens, a aspherical microcylinder lens, and a Fresnel lens.

16. The arrangement of claim 1, wherein the direction element comprises at least one of a doublet lens, a biconvex lens, a planoconvex lens.

17. The arrangement of claim 16, wherein the direction element comprises spherical surfaces.

18. The arrangement of claim 16, wherein the direction element comprises aspherical surfaces.

19. The arrangement of claim 1, further comprising an optical element arranged adjacnt the direction element.

20. The arrangement of claim 19, wherein the optical element evenly deflects the beams in the second direction.

21. The arrangement of claim 19, wherein the optical element comprise at least one of blazed gratings, a prism stack, and a mirror stack.

22. The arrangement of claim 19, wherein the optical element is sectioned and deflects the beams in the second direction.

23. The arrangement of claim 1, wherein the redirection element comprises at least one of an array of blazed gratings, a prism stack, and a mirror stack.

24. The arrangement of claim 1, further comprising an deflecting element arranged between the direction element and the redirection element.

25. The arrangement of claim 24, wherein the deflecting element is arranged adjacent the redirection element, whereby the deflecting element deflects beams in the first direction such that they are emitted from the redirection element parallel to the optical axis.

26. The arrangement of claim 24, wherein the deflecting element comprises at least one of an array of blazed gratings, a prism stack, and a mirror stack.

27. The arrangement of claim 24, wherein the deflecting element comprises a diffraction element.

28. The arrangement of claim 1, wherein the redirection element comprises a diffraction element.

29. The arrangement of claim 1, further comprising a lens located between the direction element and the redirection element, whereby the lens causes a collimation of individual beams in the second direction.

30. The arrangement of claim 29, wherein the lens is located adjacent the redirection element and comprises at least one of a doublet lens, a biconvex lens, and a planoconvex lens.

31. The arrangement of claim 30, wherein the direction element comprises spherical surfaces.

32. The arrangement of claim 30, wherein the direction element comprises aspherical surfaces.

33. The arrangement of claim 1, further comprising a focusing lens arranged downstream of the redirection element, whereby the focusing lens focuses the beams into at least one focus spot.

34. The arrangement of claim 33, wherein the focusing lens comprises at least one of an achromate lens, an achromate and a meniscus lens, a planoconvex lens, a planoconvex lens, a meniscus lens, and a biconvex lens.

35. The arrangement of claim 34, wherein the focusing lens comprises a spherical profile form.

36. The arrangement of claim 34, wherein the focusing lens comprises an aspherical profile form.

37. An optical arrangement for symmetrizing beams comprising:

a plurality of laser diodes emitting beams and arranged to form an array;

a plurality of microcylinder lenses adjacent the array;

a direction element arranged downstream of the plurality of microcylinder lenses;

the direction element deflecting some beams in a first direction, whereby each of the beams is deflected by a different angle in the first direction, such that central points of individual beams converge at a predetermined distance in the first direction;

the direction element deflecting some beams in a second direction such that each of the beams converges at a predetermined distance in the second direction; and

a redirection element arranged at a distance downstream the direction element,

wherein the redirection element compensates for different angles of deflection of the beams transmitted through the direction element.

38. An optical arrangement for symmetrizing beams comprising:

a plurality of laser diodes emitting beams and arranged to form an array;

a plurality of microcylinder lenses adjacent the array;

a direction element arranged downstream of the microcylinder lenses;

the direction element deflecting some beams in a first direction, whereby each of the beams is deflected by a different angle in the first direction, such that central points of individual beams converge at a predetermined distance in the first direction;

the direction element deflecting some beams in a second direction such that each of the beams converges at a predetermined distance in the second direction;

a redirection element arranged at a distance downstream of the direction element;

at least one lens arranged adjacent the redirection element; and

at least one optical fiber arranged downstream the redirection element and the at least one lens,

wherein at least some of the beams exiting the redirection element are directed to a common focal spot on the at least one optical fiber.