Abstract: A thorium-free low absorption coating for infrared CO.sub.2 laser optics comprises an interior BaF.sub.2 layer formed on a substrate and an exterior layer formed over the interior layer to a predetermined thickness sufficient to substantially prevent water adsorption by the interior layer. Generally, the predetermined thickness is greater than about 11000 .ANG., and in one embodiment of a two-layer low absorption coating designed for antireflection at 10.6 microns, the exterior layer has a physical thickness in a range between about 24600 .ANG. and 22800 .ANG., and preferably about 24000 .ANG.. In the preferred two-layer AR coating embodiment, the exterior layer defines a cover layer and an absentee layer, and the interior layer is relatively thin. The preferred exterior layer and the preferred substrate consist essentially of ZnSe. Multilayer stacked coatings of more than two layer can also be formed to provide low absorption partially reflective or totally reflective coatings as well as AR coatings.

Abstract: An image projection system employing microlaser and/or diode laser arrays. Each laser in each array is individually addressable. The system includes three linear laser arrays, one red, one green, and one blue, each individually addressable laser being powered and modulated in accordance with the input image signal. When microlaser arrays, which are energized by laser diode pumps, are used, the laser diode pumps are formed in equivalent arrays. The laser output beams are combined in a dichroic prism and reflected off a rotating multifaceted scanning mirror which effects two dimensional scanning as it rotates. The image beam reflected from the scanner passes through an imaging lens, a speckle eliminator and then onto the projection screen. The invention also includes the method of generating and scanning the image beam, as well as the novel speckle eliminator and the microlaser array configured for optimally close spacing to achieve the desired result.

Abstract: A fiber optic coupler for coupling an asymmetrical beam such as provided by a laser diode into a fiber optic cable. The coupler comprises at least one fiber optic cable having a longitudinally-formed approximately flat entrance facet and a cylindrical curved reflective surface formed on a first end. The curved reflective surface defines a line focus proximate to the entrance facet. A support structure situates the entrance facet proximate to the laser diode so that the line focus is approximately aligned with the narrow output aperture of the laser diode. The fiber optic cable may have any cross-section, such as circular, rectangular, or square. The fiber optic cable also includes a main body for receiving and transmitting the coupled laser radiation, and an output end having an approximately flat exit facet for outputting the laser radiation.

Abstract: A composite cavity continuous wave (cw) microlaser that lases at two fundamental wavelengths, denoted by .lambda..sub.1 and .lambda..sub.2, which are frequency-mixed in a suitable nonlinear crystal oriented within an optically resonant cavity for phase-matched frequency mixing to generate radiation at a third wavelength. The optically resonant cavity is defined by a first reflective surface and a second reflective surface, both of which are substantially reflective at a first and a second wavelength. A highly absorbing solid-state gain material, preferably Nd:YVO.sub.4, which has a first gain transition at the first wavelength and a second gain transition at the second wavelength different from the first wavelength is disposed within the optically resonant cavity. The highly absorbing solid-state gain material is closely coupled to the first reflective surface to promote single mode operation of both fundamental lasing frequencies.

Abstract: A longitudinally-cooled laser element assembly comprises an optically transparent heat sink (OTH) coupled to a laser element and a heat sink. An etalon structure including a first flat surface and a second, substantially parallel flat surface is formed in the laser element and/or the OTH. In some embodiments, a balanced etalon is provided by forming a reflector on the second flat surface of the etalon that has a reflectivity approximately equal to the Fresnel loss at the interface between the OTH and the laser element. In some embodiments the laser element assembly includes a second OTH coupled to the laser element at a second interface, thereby defining a second Fresnel loss. Preferably, the second OTH has an index of refraction substantially equal to the index of refraction of the first OTH, so that said first and second Fresnel losses are approximately equal and a balanced etalon is formed. In some embodiments the laser element comprises a solid-state gain medium.

Abstract: An optical fiber coupling assembly for substantially preserving polarization of transmitted optical radiation, including at least one multimode optical fiber situated in a housing that includes means for distributing pressure on the optical fiber and reducing stress on the multimode optical fiber. In one embodiment, the housing has a first and a second side, and includes a channel having a first end opening on the first side and a second end within the housing. A cavity connected to the second end of the channel is formed within the housing. An aperture formed in the housing connects the cavity to the second side. The channel, cavity, and aperture together provide a passageway for the optical fibers from the first side to the second side of the housing. In the preferred embodiment the aperture bundles a plurality of fibers together in an approximately circular cross-section.

Abstract: An intracavity frequency-converted laser having an intracavity reflector situated to reflect converted radiation at a nonzero angle with respect to the optical axis. The laser includes an optical cavity that defines an optical axis, a gain medium for providing a fundamental laser emission, a pump source for pumping the gain medium, and a nonlinear material for frequency converting the fundamental laser emission to provide first and second converted beams that propagate in opposite directions within the optical cavity. An angled reflector that reflects optical radiation at the converted wavelength, but is transmissive at the fundamental wavelength is situated within the optical cavity to reflect one of the converted beams along a path angled with respect to the optical axis. Advantageously, reflecting the converted radiation before it propagates through the gain medium avoids absorption losses.

Abstract: A monolithic diode pumped solid-state laser (11) comprising as the laser host neodymium-doped yttrium orthovanadate (Nd:YVO.sub.4) (12, 52) or neodymium-doped gadolinium orthovanadate (Nd:GdVO.sub.4) (57, 67) operating on the .sup.4 F.sub.3/2 .fwdarw..sup.4 I.sub.9/2 (.about.914 nm or .about.912 nm respectively) transition, to which a suitable nonlinear optic material (16), such as potassium niobate (KNbO.sub.3) or beta barium borate (BBO), is bonded. The nonlinear crystal gives rise to intracavity frequency doubling to .about.457 or .about.456 nm. The microlaser is a composite cavity formed from a gain medium crystal and a nonlinear frequency doubling material which together have four spaced parallel dielectrically coated faces (14, 17, 18, 15) and which is positioned in close proximity to a diode laser pump source (13) for phase-matched harmonic generation of blue light along an axis of propagation which lies substantially perpendicular to the two faces of the composite cavity.

Abstract: A fiber optic coupler for coupling an asymmetrical beam such as provided by a laser diode into a fiber optic cable. The coupler comprises at least one fiber optic cable having a first end including a tapered section that has an approximately flat coupling facet for receiving the asymmetrical beam and an approximately flat tapered surface adjacent to the coupling facet for reflecting the rapidly diverging radiation, a main body for receiving and transmitting the reflected laser radiation, and an output end having an approximately flat output facet. A support structure situates the coupling facet proximate to the laser diode. A second, approximately flat tapered surface may be formed in the tapered section opposite the first tapered surface. The fiber optic cable may have any cross-section, such as circular, rectangular, or square.

Abstract: A dual wavelength continuous wave (cw) solid state microlaser device that provides simultaneous laser action at a first and a second wavelength. The laser comprises a solid state gain material including a rare earth element having a first gain transition at the first wavelength and a second gain transition at the second wavelength. The gain material defines a block having a first face and a second, opposite face. A first reflective surface that is substantially reflective at both the first and second wavelengths is closely coupled to the first face. An output coupler provides a second reflective surface that is partially reflective at both the first and the second wavelengths, which is oriented with respect to the first reflective face to define an optical cavity through the first and second faces of the solid state gain material. An optical pump source is provided to end pump the solid state gain material with continuous pump radiation at a pump wavelength that is highly absorptive by the gain material.

Abstract: A monolithic diode pumped solid-state laser (11) comprising as the laser host neodymium-doped yttrium orthovanadate (Nd:YVO.sub.4) (12, 52) or neodymium-doped gadolinium orthovanadate (Nd:GdVO.sub.4) (57, 67) operating on the .sup.4 F.sub.3/2 .fwdarw..sup.4 I.sub.9/2 (.about.914 nm or .about.912 nm respectively) transition, to which a suitable nonlinear optic material (16), such as potassium niobate (KNbO.sub.3) or beta barium borate (BBO), is bonded. The nonlinear crystal gives rise to intracavity frequency doubling to .about.457 or .about.456 nm. The microlaser is a composite cavity formed from a gain medium crystal and a nonlinear frequency doubling material which together have four spaced parallel dielectrically coated faces (14, 17, 18, 15) and which is positioned in close proximity to a diode laser pump source (13) for phase-matched harmonic generation of blue light along an axis of propagation which lies substantially perpendicular to the two faces of the composite cavity.

Abstract: An image projection system employing microlaser and/or diode laser arrays. Each laser in each array is individually addressable. The system includes three linear laser arrays, one red, one green, and one blue, each individually addressable laser being powered and modulated in accordance with the input image signal. When microlaser arrays, which are energized by laser diode pumps, are used, the laser diode pumps are formed in equivalent arrays. The laser output beams are combined in a dichroic prism and reflected off a rotating multifaceted scanning mirror which effects two dimensional scanning as it rotates. The image beam reflected from the scanner passes through an imaging lens, a speckle eliminator and then onto the projection screen. The invention also includes the method of generating and scanning the image beam, as well as the novel speckle eliminator and the microlaser array configured for optimally close spacing to achieve the desired result.

Abstract: A flexible light conduit which preserves the coherence of a transmitted beam. Several conduit elements having optical elements mounted inside each one are connected together to form a chain. Each conduit element is tiltably coupled to each adjacent conduit element in the chain. The optical elements may be refractive or reflective. The conduit preserves the spatial coherence properties of the beam so the input image is reimaged at a distant place, having passed through the series of relay optical elements through the angles permitted by the coupling members.