Device for optically rotating light beams in a beam array

• US 5,592,333 A
• Filed: 07/11/1996
• Issued: 01/07/1997
• Est. Priority Date: 07/29/1994
• Status: Expired due to Term

• Current Assignee: JDS Uniphase Corporation (Lumentum Holdings Inc.)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Lewis, John R.
• Primary Examiner(s): Epps, Georgia Y.
• Assistant Examiner(s): MACK, RICKY LEVERN
• Application Number:
  US08/678,150
• Time in Patent Office: 180 Days
• Field of Search: 385/123, 385/124, 385/125, 385/126, 385/127, 385/146, 385/147, 359/625, 359/628, 359/741, 359/619, 359/641, 372/6, 372/7, 372/8, 372/109
• US Class Current: 359/628
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• 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 27/095 Refractive optical elements
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 27/0966 Cylindrical lenses cylindrical lenses per se G02B3/06
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/425 Optical features semiconductor laser arrays H01S5/40; hybrid LED arrays H01L25/0753; monolithic LED arrays H01L27/153
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B

Abstract

An optical apparatus for converting an incoming array of light beams by interchanging the horizontal and vertical components of each beam, the apparatus having a series of grooves, one groove for each incoming beam, where each groove comprises two reflecting surfaces: a first reflecting surface operating to intercept the corresponding beam and reflect it to a second reflecting surface along a first path of travel, that is folded with respect to the incoming beam'"'"'s direction of propagation, while rotating one of the beam'"'"'s azimuths, and the second reflecting surface operating to intercept the beam reflected off the first surface and to direct it along a second path of travel, folded with respect to the first path of travel, while rotating the beam'"'"'s other azimuth.

Claims

1. An optical apparatus for optically rotating light beams in a beam array, said apparatus comprising:

a plurality of light sources, each said light source producing a light beam having divergence defined both in a first azimuthal direction orthogonal to the direction of propagation and in a second azimuthal direction orthogonal both to the direction of propagation and to the first azimuthal direction, said light beams oriented such that their respective first azimuthal directions are substantially parallel to one another; and

a substrate having a grooved surface, said grooved surface comprising a plurality of adjacent grooves having at least a one-to-one correspondence with the light beams to be rotated, each said groove being formed of first and second reflecting surfaces which intersect along a common vertex edge and form a dihedral angle (Φ

) between them, each said groove vertex edge being oriented at an aspect angle (ψ

) with respect to the direction of propagation of the corresponding light beam so that said first reflecting surface is positioned to intercept the corresponding light beam and to direct it as an inverted beam to said second reflecting surface along a first path of travel, that is folded with respect to the direction of propagation, while said second reflecting surface operates to intercept the inverted beam reflected off said first reflecting surface and to direct it as a rotated beam along a second path of travel, folded with respect to said first path of travel, said rotated beams acquiring an orientation such that their respective second azimuthal directions are substantially parallel to one another.

2. The optical apparatus of claim 1 wherein said first reflecting surface intersects along a common apex edge with the second said reflecting surface of an adjacent groove to form a reflecting pair defining a dihedral angle, (Φ

₂) between them.

3. The optical apparatus of claim 1 wherein all said first reflecting surfaces are parallel to one another and all said second reflecting surfaces are parallel to one another.

4. The optical apparatus of claim 1 wherein said reflecting surfaces are of essentially the same width.

5. The optical apparatus of claim 1 wherein said vertex edges are parallel to one another.

6. The optical apparatus of claim 1 wherein said dihedral angle (Φ

) is substantially 60°

.

7. The optical apparatus of claim 6 wherein said aspect angle (ψ

) is substantially 54.7°

.

8. The optical apparatus of claim 1 wherein said substrate comprises a monocrystalline substance.

9. The optical apparatus of claim 8 wherein said monocrystalline substance comprises silicon.

10. The optical apparatus of claim 9 wherein said dihedral angle (Φ

) is substantially 70.5°

.

11. The optical apparatus of claim 8 wherein said monocrystalline substance comprises gallium arsenide.

12. The optical apparatus of claim 1 wherein said reflecting surfaces comprise a coating to increase the reflection of the light beam by said reflecting surfaces.

13. The optical apparatus of claim 2 wherein said substrate comprises an optically-transparent material having an index of refraction n₂ >

n₁, where n₁ is the index of refraction of the ambient medium, such that internal reflections occur within said material at said reflecting surfaces.

14. The optical apparatus of claim 13 wherein all said first reflecting surfaces are parallel to one another and all said second reflecting surfaces are parallel to one another.

15. The optical apparatus of claim 13 wherein said reflecting surfaces are of essentially the same width.

16. The optical apparatus of claim 13 wherein said apex edges are parallel to one another.

17. The optical apparatus of claim 13 wherein said dihedral angle (Φ

₂) is substantially 60°

.

18. The optical apparatus of claim 17 wherein said aspect angle (ψ

) is substantially 54.7°

.

19. The optical apparatus of claim 13 wherein said material is comprised of glass transparent to infrared wavelengths.

20. The optical apparatus of claim 13 further comprising means for collimating said light beams in at least one azimuthal direction.

21. An optical apparatus for optically rotating light beams in a beam array, said apparatus comprising:

a plurality of light sources, each said light source producing a light beam having divergence defined both in a first azimuthal direction orthogonal to the direction of propagation and in a second azimuthal direction orthogonal both to the direction of propagation and to the first azimuthal direction, said light beams oriented such that their respective first azimuthal directions are substantially parallel to one another; and

a plurality of flat plates, each said plate having a sloping surface extending from a surface of said plate to an edge of said plate, said plurality of plates being stacked in a linear array such that alternating pairs of said plates are positioned with corresponding sloping surfaces in opposed relationship to one another, each said opposed sloping surface pair forming a concave reflecting pair defining a dihedral angle of (Φ

) said dihedral angle having a vertex edge common to both said sloping surfaces in said reflecting pair, each said reflecting pair further having a one-to-one correspondence with the optical beams to be rotated, each said reflecting pair vertex edge being oriented at an aspect angle (ψ

) with respect to the direction of propagation of the corresponding light beam so that one of said sloping surfaces in said reflecting pair is positioned to intercept the corresponding light beam and to direct it as an inverted beam to the other of the said sloping surfaces in the reflecting pair along a first path of travel, that is folded with respect to the direction of propagation, while said other of the sloping surfaces operates to intercept the inverted beam reflected off said one of said sloping surfaces and to direct it as a rotated beam along a second path of travel, said rotated beams acquiring an orientation such that their respective second azimuthal directions are substantially parallel to one another.

22. The optical apparatus of claim 21 wherein said dihedral angle (Φ

) is substantially 60°

.

23. An optical coupler for converting an incoming array of light beams into a single beam of optical radiation, comprising:

first means for collimating each light beam along a first azimuth, to decrease the growth of the light beam in a first azimuth as the beam passes through said first means for collimating and remains decreased in said first azimuth as the beam continues to propagate through said optical coupler;

an optical beam rotator for transforming the array of light beams, said beam rotator comprising;

a substrate having a grooved surface, said grooved surface comprising a plurality of adjacent grooves having a one-to-one correspondence with the light beams to be transformed,

each said groove being formed of first and second reflecting surfaces which intersect along a common vertex edge and form a dihedral angle (Φ

) between them, the said vertex edge of each said groove being oriented at an aspect angle (ψ

) with respect to the initial direction of propagation of the corresponding light beam so that said first reflecting surface is positioned to intercept the incoming beam and to direct it to said second reflecting surface along a first path of travel, that is folded with respect to the incoming beam direction of propagation, while rotating one of the beam'"'"'s azimuths, while said second reflecting surface operates to intercept the beam reflected off said first surface and to direct it along a second path of travel, folded with respect to said first path of travel, while rotating the light beam'"'"'s other azimuth, whereby the horizontal and vertical components of the initial orientation of the light beam are interchanged;

second means for collimating each light beam along a second azimuth, to decrease the growth of the light beam in said second azimuth as the beam passes through said second means for collimating and remains decreased in said second azimuth as the beam continues to propagate through said optical coupler, said second azimuth being orthogonal both to the direction of propagation of the light beam and to said first azimuth; and

means for converging the array of light beams so that the array strikes a predetermined target area.

24. The optical convertor of claim 23 wherein said dihedral angle (Φ

) is substantially 60°

.

25. The optical convertor of claim 23 wherein said substrate comprises a monocrystalline substrate.

26. The optical convertor of claim 25 wherein said monocrystalline substrate comprises silicon.

27. The optical convertor of claim 26 wherein said dihedral angle (Φ

) is substantially 70.5°

.

28. The optical convertor of claim 25 wherein said monocrystalline substance comprises gallium arsenide.

29. An optical coupler for converting an incoming array of optical beams into a single beam of optical radiation, comprising:

a monolithic optical beam rotator for transforming the array of optical beams, said optical beam rotator comprising an optically-transparent material having an index of refraction n₂ >

n₁, where n₁ is the index of refraction of the ambient medium,

said optical beam rotator having a cylindrical surface, for collimating each incoming optical beam along a first azimuth, to decrease the growth of the optical beam in said first azimuth as the beam passes through said cylindrical surface, and remains decreased in said first azimuth as the beam emerges from said optical beam rotator and continues to propagate through said optical coupler,

said optical beam rotator further having a grooved surface, said grooved surface comprising a plurality of adjacent grooves, each said groove being formed of first and second reflecting surfaces, said first reflecting surface intersecting along a common apex edge with the second said reflecting surface of an adjacent groove to form a concave reflecting pair defining a dihedral angle (Φ

₂) between them, each said reflecting pair having a one-to-one correspondence with the optical beams to be transformed,

the said apex edge of each said reflecting pair being oriented at an aspect angle (ψ

) with respect to the initial direction of propagation of the corresponding optical beam so that said first reflecting surface is positioned to intercept the incoming beam and to direct it to said second reflecting surface along a first path of travel, that is folded with respect to the incoming beam direction of propagation, while rotating one of the beam'"'"'s azimuths, while said second reflecting surface operates to intercept the beam reflected off said first surface and to direct it along a second path of travel, folded with respect to said first path of travel, while rotating the optical beam'"'"'s other azimuth, whereby the horizontal and vertical components of the initial orientation of the optical beam are interchanged;

means for collimating each optical beam along a second azimuth, to decrease the growth of the optical beam in said second azimuth as the beam passes through said means for collimating and remains decreased in said second azimuth as the beam continues to propagate through said optical coupler, said second azimuth being orthogonal both to the direction of propagation of the optical beam and to said first azimuth; and

means for converging the array of optical beams so that the array strikes a predetermined target area.

30. The optical coupler of claim 29 wherein said dihedral angle (Φ

₂) is substantially 60°

.

31. An optical coupler for converting an incoming array of optical beams into a single beam of optical radiation, comprising:

first means for collimating each optical beam along a first azimuth, to decrease the growth of the optical beam in said first azimuth as the optical beam passes through said first means for collimating and remains decreased in said first azimuth as the optical beam continues to propagate through said optical coupler;

an optical beam rotator comprising;

a plurality of flat plates, each said plate having a sloping surface extending from a surface of said plate to an edge of said plate, said plurality of plates being stacked in a linear array such that alternating pairs of said plates are positioned with corresponding sloping surfaces in opposed relationship to one another, each said opposed sloping surface pair forming a concave reflecting pair defining a dihedral angle (Φ

) said dihedral angle having a vertex edge common to both said sloping surfaces in said reflecting pair, each said reflecting pair further having at least a one-to-one correspondence with the optical beams to be rotated,

said vertex edge of each said reflecting pair being oriented at an aspect angle (ψ

) with respect to the incoming direction of propagation of the corresponding optical beam so that one of the said sloping surfaces in said reflecting pair is positioned to intercept the incoming optical beam and to direct it as an inverted beam to the other of the said sloping surfaces in the reflecting pair along a first path of travel, that is folded with respect to the incoming direction of propagation, while said other of the sloping surfaces operates to intercept the inverted beam reflected off said one of said sloping surfaces and to direct it as a rotated beam along a second path of travel, folded with respect to said first path of travel; and

means for converging the rotated beams to strike a predetermined target area.

32. The optical coupler of claim 31 wherein said dihedral angle (Φ

) is substantially 60°

.