Monochromatic R,G,B laser light source display system and method
First Claim
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1. An R,G,B pulsed laser light source with reduced speckle noise adapted for use with a display system, which light source generates R, G and B beams and comprises:
- a laser with a laser medium producing a pulsed laser output beam of selected pulse width and wavelength;
an R-channel receiving a first portion of the output beam and generating the R beam, with the R-channel including a resonant cavity with a first nonlinear crystal producing optical radiation having a first wavelength that is greater than the wavelength of the output beam and a spectral width that is greater than a spectral width of the output beam, and a second nonlinear crystal that combines the radiation of the first wavelength with the first portion of the output beam to generate the R beam by sum frequency mixing, said R-beam having a spectral width determined by the spectral width of the optical radiation of the first wavelength;
a G-channel receiving a second portion of the output beam and generating the G beam, with the G-channel including a resonant cavity with a third nonlinear crystal producing second harmonic optical radiation of the output beam, with the cavity of the G-channel further including an etalon that produces a plurality of longitudinal G-channel resonant cavity modes which define a spectral width of the G-channel; and
a B-channel receiving a third portion of the output beam and generating the B beam, with the B-channel including a fourth nonlinear crystal that frequency-doubles the third portion of the output beam, and a lasing cavity having a Ti;
S laser crystal pumped with the frequency-doubled output beam and producing a lasing wavelength that is twice the wavelength of the B-beam, said lasing wavelength being frequency-doubled by a fifth nonlinear crystal located in the lasing cavity and producing the B-beam;
with the spectral width of the R-channel and the G-channel reducing the speckle noise of the R,G,B pulsed laser light source.
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Abstract
A monochromatic red (R), green (G), blue (B) pulsed laser light source (FIG. 2) for use in a full color video/image display system particularly an LCD display system (FIG. 3), the light source generating R,G,B laser beams with minimum speckle noise, and having digital color space conversion incorporated within.
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Citations
28 Claims
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1. An R,G,B pulsed laser light source with reduced speckle noise adapted for use with a display system, which light source generates R, G and B beams and comprises:
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a laser with a laser medium producing a pulsed laser output beam of selected pulse width and wavelength;
an R-channel receiving a first portion of the output beam and generating the R beam, with the R-channel including a resonant cavity with a first nonlinear crystal producing optical radiation having a first wavelength that is greater than the wavelength of the output beam and a spectral width that is greater than a spectral width of the output beam, and a second nonlinear crystal that combines the radiation of the first wavelength with the first portion of the output beam to generate the R beam by sum frequency mixing, said R-beam having a spectral width determined by the spectral width of the optical radiation of the first wavelength;
a G-channel receiving a second portion of the output beam and generating the G beam, with the G-channel including a resonant cavity with a third nonlinear crystal producing second harmonic optical radiation of the output beam, with the cavity of the G-channel further including an etalon that produces a plurality of longitudinal G-channel resonant cavity modes which define a spectral width of the G-channel; and
a B-channel receiving a third portion of the output beam and generating the B beam, with the B-channel including a fourth nonlinear crystal that frequency-doubles the third portion of the output beam, and a lasing cavity having a Ti;
S laser crystal pumped with the frequency-doubled output beam and producing a lasing wavelength that is twice the wavelength of the B-beam, said lasing wavelength being frequency-doubled by a fifth nonlinear crystal located in the lasing cavity and producing the B-beam;
with the spectral width of the R-channel and the G-channel reducing the speckle noise of the R,G,B pulsed laser light source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16, 17, 18, 19, 20, 21)
a) a neodymium-yttrium vanadate laser medium with a pump end with an active mirror;
b) a diode laser bar with output wavelength of 807 nm;
c) an optical fiber means to deliver the diode laser bar output to the pump end of the laser medium;
d) a Q-switch means to pulse the laser beam from the laser medium; and
e) an output beam coupler to transmit a pulsed laser beam.
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8. The source of claim 1 wherein the laser comprises:
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a) a neodymium-yttrium vanadate laser medium;
b) a single or multiple diode laser bar with an output wavelength of 807 nm;
c) means to focus the diode laser bar output to one or both sides of the laser medium;
d) a Q-switch means to pulse the laser beam from the laser medium; and
e) an end mirror and an output beam coupler to resonate and transmit a pulsed laser beam.
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9. The source of claim 1 wherein the output laser beam wavelength is 1047 nm or 1064 nm.
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10. The source of claim 1, further including:
means to divide the output signal into the three separate portions of the output beams.
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11. The source of claim 1 which includes active modelock means to produce quasi-cw operation of the R,G,B laser light source.
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12. The source of claim 1, further including a laser power amplifier means to amplify the power of the output beam.
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13. The source of claim 1, wherein the first nonlinear crystal comprises a potassium titanyl arsenate (KTA) and the second nonlinear crystal is selected from the group consisting of KTA or lithium triborate (LBO).
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16. The system of claim 13, further comprising:
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a first optical means to receive and shape the R,G,B beams;
a spatial light modulator means to receive the R,G,B beams from the optical means, and to modulate the R,G,B beams to produce a full color video image;
electronic means to operate the spatial light modulator means; and
a second optical means to relay, combine, and project a full color video image on a screen.
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17. The system of claim 16 wherein the spatial light modulator means comprises three transmissive or reflective LCD panels, one for each R,G,B beam.
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18. The system of claim 16 wherein the first optical means includes expander, collimator and micro-array lens means to receive the R,G,B beams and to increase the R,G,B light transmission efficiency and minimize diffraction.
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19. The system of claim 16 wherein the spatial light modulator means comprise three transmissive LCD panels, one for each R,G,B beam, and which system includes:
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a) a first optical means which comprises a beam expander, collimator and micro-array lens means to expand, to collimate, and to increase transmission efficiency of the R,G,B beams from the light source and incident on the LCD panels;
b) a second optical means which comprises an optical means to re-collimate the R,G,B beams on the opposite side of the LCD panels; and
c) projection means to project the re-collimated R,G,B beams onto a screen.
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20. The system of claim 16 wherein the electronic means includes digital color space conversion means to translate electronic input video chromatic signals into electronic signals within R,G,B laser color space.
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21. The system of claim 16 wherein the output laser beam wavelength is 1047 nm, 1064 nm or 1342 nm.
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14. A color image video display system comprising:
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an R,G,B pulsed laser light source with reduced speckle noise, which light source generates R, G and B beams and includes a laser with a laser medium producing a pulsed laser output beam of selected pulse width and wavelength;
an R-channel receiving a first portion of the output beam and generating the R beam, with the R-channel including a resonant cavity with a first nonlinear crystal producing optical radiation having a first wavelength that is greater than the wavelength of the output beam and a spectral width that is greater than a spectral width of the output beam, and a second nonlinear crystal that combines the radiation of the first wavelength with the first portion of the output beam to generate the R beam by sum frequency mixing, said R-beam having a spectral width determined by the spectral width of the optical radiation of the first wavelength;
a G-channel receiving a second portion of the output beam and generating the G beam, with the G-channel including a resonant cavity with a third nonlinear crystal producing second harmonic optical radiation of the output beam, with the cavity of the G-channel further including an etalon that produces a plurality of longitudinal G-channel resonant cavity modes which define a spectral width of the G-channel; and
a B-channel receiving a third portion of the output beam and generating the B beam, with the B-channel including a fourth nonlinear crystal that frequency-doubles the third portion of the output beam, and a lasing cavity having a Ti;
S laser crystal pumped with the frequency-doubled output beam and producing a lasing wavelength that is twice the wavelength of the B-beam, said lasing wavelength being frequency-doubled by a fifth nonlinear crystal located in the lasing cavity and producing the B-beam.- View Dependent Claims (15)
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22. A method of producing a pulsed laser R, G, B light source of reduced speckle noise useful in a full color display system, which method comprises:
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a) providing a pulsed laser output beam;
b) generating by crystal-based, non-linear frequency conversion, a G beam with spatial incoherency, by multi-longitudinal mode operation produced by an etalon located in a G-channel cavity, from the output beam;
c) generating, by optically pumping a Ti;
S laser crystal with frequency-doubled output beam radiation to produce an intermediate lasing wavelength and crystal-based, intra-cavity non-linear frequency conversion of the intermediate lasing wavelength, a B beam from the output beam;
d) generating from the output beam, by crystal-based, non-linear frequency conversion, an intermediate beam having a spectral width substantially greater than a spectral width of the output beam and a wavelength longer than the wavelength of the output beam, and subsequent crystal-based, non-linear sum frequency mixing of the intermediate beam with the output beam an R beam with a spectral width determined by the spectral width of the intermediate beam; and
e) mixing the generated R,G and B beams to provide a full color beam with reduced speckle noise. - View Dependent Claims (23, 24, 25, 26, 27, 28)
a) amplifying the pulsed laser output beam by a power amplifier means having a neodymium-yttrium vanadate laser medium; and
b) side-pumping the neodymium-yttrium vanadate laser medium with a single or multiple diode laser bar.
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28. The method of claim 22 which includes generating the output laser beam at a wavelength of 1047 nm or 1064 nm.
Specification