PATTERNED RETARDER AND OPTICAL ENGINE FOR LASER PROJECTION APPARATUS

• US 20140036943A1
• Filed: 03/15/2013
• Published: 02/06/2014
• Est. Priority Date: 07/31/2012
• Status: Active Grant

• Current Assignee: Barco NV
• Original Assignee: Barco NV
• Inventors: Vermeirsch, Koenraad, Janssens, Peter
• Granted Patent: US 9,466,941 B2
• Time in Patent Office: Days
• US Class Current: 372/27
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G02B 27/281 used for attenuating light intensity, e.g. comprising rotatable polarising elements
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 27/288 Filters employing polarising elements, e.g. Lyot or Solc filters G02B5/3016 takes precedence
• CPC Class Codes: H01S 3/10061 Polarization control
• CPC Class Codes: H01S 5/0085 for modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4093 Red, green and blue [RGB] generated directly by laser action or by a combination of laser action with nonlinear frequency conversion
• CPC Class Codes: H04N 13/324 Colour aspects
• CPC Class Codes: H04N 13/337 using polarisation multiplexing
• CPC Class Codes: H04N 13/363 using image projection screens volumetric display H04N13/388
• CPC Class Codes: H04N 9/3158 for controlling the spectrum
• CPC Class Codes: H04N 9/3161 using laser light sources using laser beams scanning the display screen H04N9/3129
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

A patterned retarder is described that may be used with a laser source array to obtain a combined beam suitable for three-dimensional laser image projection using orthogonal polarization states and/or orthogonal color spaces.

Claims

1. An apparatus for producing a laser beam, said apparatus comprising:

a patterned retarder comprising a plurality N of pattern elements; and

a plurality N of laser sources, each configured to produce a corresponding laser beam,

wherein each of the plurality N of laser sources is arranged to direct the corresponding laser beam to radiate onto an entrance side of a corresponding one of the pattern elements and to exit from an exit side of the pattern element,

wherein the plurality N of pattern elements includes a plurality of first pattern elements and a plurality of second pattern elements, and

wherein, for each of the plurality of first pattern elements, variation of an arc angle between representation points on a Poincaré

sphere of (A) a polarization state of the corresponding laser beam at the entrance side and (B) a polarization state of the corresponding laser beam at the exit side is within ten percent of a value P1, and

wherein, for each of the plurality of second pattern elements, variation of an arc angle between representation points on the Poincaré

sphere of (A) a polarization state of the corresponding laser beam at the entrance side and (B) a polarization state of the corresponding laser beam at the exit side is within ten percent of a value P2, and

wherein a difference between the value P1 and the value P2 is pi radians.

2. The apparatus according to claim 1, wherein, for at least one among the plurality of first pattern elements, the polarization state of a laser beam exiting the pattern element is linear with an orientation perpendicular to an orientation of linear polarized light of a laser beam exiting at least one among the plurality of second pattern elements of the patterned retarder.

3. The apparatus according to claim 1, wherein, for at least one among the plurality of first pattern elements, the polarization state of a laser beam exiting the pattern element is circular with opposite handedness to circular polarized light of a laser beam exiting at least one among the plurality of second pattern elements of the patterned retarder.

4. The apparatus according to claim 1, wherein a cross-section of each of the plurality N of laser beams is at least twice as long along a first direction than along a second direction that is orthogonal to the first direction.

5. The apparatus according to claim 1, wherein a surface plane of the pattern retarder is perpendicular to a first propagation direction, and

wherein a propagation direction of each of the plurality N of laser beams is parallel to the first propagation direction.

6. The apparatus according to claim 1, wherein a difference between a first wavelength λ

1 and a second wavelength λ

2 is at least 0.5 nanometers and not greater than five nanometers, and

wherein the plurality of N laser sources includes a first plurality of laser sources configured to produce beams having the first wavelength and a second plurality of laser sources configured to produce beams having the second wavelength.

7. The apparatus according to claim 6, wherein the first plurality of laser sources includes a source arranged to direct a beam onto one among the plurality of first pattern elements and a source arranged to direct a beam onto one among the plurality of second pattern elements, and

wherein the second plurality of laser sources includes a source arranged to direct a beam onto one among the plurality of first pattern elements and a source arranged to direct a beam onto one among the plurality of second pattern elements.

8. The apparatus according to claim 1, wherein each of said plurality of first pattern elements comprises a nanolaminate.

9. The apparatus according to claim 1, wherein said plurality of first pattern elements is arranged relative to said plurality of second pattern elements in one among a striped pattern and a checkerboard pattern.

18. The apparatus according to claim 1, wherein, for each of the plurality of first pattern elements, said variation of the arc angle is within five percent of the value P1, and

wherein, for each of the plurality of second pattern elements, said variation of the arc angle is within five percent of the value P2.

19. The apparatus according to claim 1, wherein, for each of the plurality of first pattern elements, said variation of the arc angle is within one percent of the value P1, and

wherein, for each of the plurality of second pattern elements, said variation of the arc angle is within one percent of the value P2.

10. An apparatus for producing a laser beam, said apparatus comprising:

a first plurality of patterned retarders, each retarder corresponding to a different one of a plurality of primary colors;

a first plurality of laser source arrays, each array corresponding to a different one of the first plurality of patterned retarders and arranged to radiate a plurality of laser beams that are directed onto the corresponding retarder; and

first color combining optics arranged to receive a combined beam from each of the first plurality of patterned retarders and to combine the received beams to produce a first multi-primary beam,

wherein, for each of said first plurality of patterned retarders, an effect of the retarder on a polarization state of an incident beam is dependent on the location of the retarder upon which the beam is incident.

11. The apparatus according to claim 10, wherein said apparatus comprises:

a second plurality of patterned retarders, each retarder corresponding to a different one of the plurality of primary colors; and

a second plurality of laser source arrays, each array corresponding to a different one of the second plurality of patterned retarders and arranged to radiate a plurality of laser beams that are directed onto the corresponding retarder;

second color combining optics arranged to receive a combined beam from each of the second plurality of patterned retarders and to combine the received beams to produce a second multi-primary beam; and

third color combining optics arranged to combine the first and second multi-primary beams to produce a combined multi-primary beam,

wherein, for each of said second plurality of patterned retarders, an effect of the retarder on a polarization state of an incident beam is dependent on the location of the retarder upon which the beam is incident.

12. The apparatus according to claim 11, wherein during a left-eye time period, the first and second pluralities of laser source arrays are controlled such that each of the first and second multi-primary beams contain only beams having a first polarization state, and

wherein during a right-eye time period, the first and second pluralities of laser source arrays are controlled such that each of the first and second multi-primary beams contain only beams having a second polarization state orthogonal to the first polarization state.

20. The apparatus according to claim 10, wherein said first plurality of patterned retarders includes a first patterned retarder comprising a plurality N of pattern elements, and

wherein, for each of the plurality N of pattern elements, the laser source array corresponding to said first patterned retarder is arranged to direct a corresponding one of a plurality N of the plurality of laser beams to radiate onto an entrance side of the pattern element and to exit from an exit side of the pattern element,

wherein the plurality N of pattern elements includes a plurality of first pattern elements and a plurality of second pattern elements, and

wherein, for each of the plurality of first pattern elements, variation of an arc angle between representation points on a Poincaré

sphere of (A) a polarization state of the corresponding laser beam at the entrance side and (B) a polarization state of the corresponding laser beam at the exit side is within ten percent of a value P1, and

wherein, for each of the plurality of second pattern elements, variation of an arc angle between representation points on the Poincaré

sphere of (A) a polarization state of the corresponding laser beam at the entrance side and (B) a polarization state of the corresponding laser beam at the exit side is within ten percent of a value P2, and

wherein a difference between the value P1 and the value P2 is pi radians.

13. A method of producing a laser beam from a plurality N of component laser beams, said method comprising:

directing the plurality N of component laser beams onto corresponding regions of a patterned retarder that has a plurality N of pattern elements,

wherein an effect of the retarder on a polarization state of an incident beam is dependent on the location of the retarder upon which the beam is incident.

14. The method according to claim 13, wherein the plurality N of pattern elements includes:

a plurality of first pattern elements, each configured to have a first effect on the polarization state of the corresponding incident beam, and

a plurality of second pattern elements, each configured to have a second effect on the polarization state of the corresponding incident beam that is different than the first effect.

15. The method according to claim 14, where the difference between the first and second effects is a change of the polarization state to its orthogonal state.

16. The method according to claim 15, wherein said directing includes, for each among the plurality N of component laser beams, directing the beam onto at least one of the plurality of first pattern elements and at least one of the plurality of second pattern elements at the same time.

17. The method according to claim 14, wherein said directing includes, for each among the plurality N of component laser beams, directing the beam onto at least one of the plurality of first pattern elements and at least one of the plurality of second pattern elements at the same time.