Abstract: There is provided a light source device which can miniaturize a two-dimensional image display device as small as possible. The light source device is provided with three coherent light sources (11a), (11b), and (11c) corresponding to red, blue, and green; prisms (12a) and (12c) for reflecting lights emitted from the coherent light sources (11a) and (11c); and a diffraction part (20) comprising a single volume hologram on which plural gratings are multiply-formed, which gratings diffract the light emitted from the coherent light source (11b), and the lights that are emitted from the coherent light sources (11a) and (11c) and reflected by the prisms (12a) and (12b) so that these lights propagate in the same optical path.

Abstract: It is designed to prevent an efficiency reduction caused by the heat generation of a rare-earth doped fiber in a wavelength converter. A wavelength converter of the present invention is provided with a laser resonator including a fiber containing an laser-active material and a fiber grating formed in the fiber, a laser light source for emitting an excitation light to the fiber, and a wavelength conversion element for converting a fundamental wave of a laser beam emitted from the laser resonator into a harmonic, wherein the fiber is coiled and has the outer side thereof coated with a heat radiating member having a reflection surface for reflecting light having a wavelength of an excitation light.

Abstract: A reflection-type laser projector (100) projects modulated laser beams outputted from a laser projection unit (40), on a screen, wherein a reflector (112) as a constituent of the screen (110) has reflection characteristics of reflecting, among the incident light, only laser beams of three colors of red, blue, and green, which are projected from the laser projection unit (40) and light in the neighboring wavelength band, and transmitting light in other wavelength bands, thereby preventing pictures on the screen (110) from becoming hard to be seen due to effects of indoor illumination or light from outdoors.

Abstract: There are provided a semiconductor laser device and an image display device that enable to efficiently release a heat from stripe active regions, and be operated at a low-consumption current and a low-consumption electric power. A semiconductor laser element includes stripe active regions for emitting laser beams. On a base block, there are formed wirings electrically connected to stripe laser electrodes of the semiconductor laser element, respectively. The stripe laser electrodes corresponding to the stripe active regions are formed in proximity to a first surface of the semiconductor laser element, close to the active regions. An electric current is supplied to the active regions from connecting portions between each of the laser electrodes and the wirings.

Abstract: A surface illumination apparatus is provided which includes a laser light source and a light guide plate upon which a laser beam emitted from the laser light source is incident through an end-surface portion and from which the laser beam is emitted through a main-surface portion on one side thereof. The laser beam is incident through an end-surface portion at an inclination angle to a main-surface portion on the other side which faces the one main-surface portion of the light guide plate, undergoes a change in the optical-path direction thereof by the other main-surface portion, is incident on the one main-surface portion and is emitted as a substantially parallel beam from the one main-surface portion.

Abstract: In a laser display that displays a video by scanning a beam from a laser light source two-dimensionally on a screen, the image quality being displayed is deteriorated markedly by speckle noises induced from coherency of the light source. A method for oscillating the screen to remove the speckles has problems that a large-scale device is necessary and the screen cannot be chosen without any restrain. A speckle pattern being generated is changed at a high speed by oscillating a light spot on the screen at a high speed using beam oscillation means 3, so that the viewer acknowledges time-mean image having no speckle noises.

Abstract: It is aimed to make optical characteristics of a photon mode optical information recording medium difficult to easily degrade with a simple construction. A disc cartridge accommodating a photon mode optical information recording medium is provided with a disc case having an opening section, and a shutter movably disposed between a closing position to close the opening section and an opening position to open the opening section. The disc case includes a light path bending portion for bending a clearance between the shutter at the closing position and the disc case at least at two points. Stray lights propagating in the clearance between the disc case and shutter is bent at least at two points.

Abstract: The present invention aims to provide a wavelength converter capable of stably obtaining a W-class high-output green laser beam and a 2D image display device using this wavelength converter. By causing a polarization direction of a laser light source for generating an excitation light and that of a light emitted from an oscillator to orthogonally intersect, the deterioration of an excitation light source by an ASE is suppressed by a polarization splitting element provided between a laser resonator and the laser light source.

Abstract: A wavelength conversion optical device is provided with a fundamental wave light source (301) which outputs a fundamental wave (L11) including a P polarized light and an S polarized light that are perpendicular to each other, and two wavelength conversion mechanisms (303a,303b) each having a polarization inversion formation part which wavelength-converts the fundamental wave (L11) to generate harmonic waves, and the first-stage wavelength conversion mechanism (303a) performs wavelength conversion of the P polarized light of the fundamental wave (L11) while the second-stage wavelength conversion mechanism (303b) performs wavelength conversion of the S polarized light of the fundamental wave (L11), whereby absorption of a second harmonic wave (green light) due to a third harmonic wave (ultraviolet light) is reduced, and stability and reliability of the wavelength-converted light output are enhanced, thereby providing a wavelength conversion optical device which can output a wavelength-converted light capable of

Abstract: A two-dimensional image formation device of the present invention is provided with a spatial light modulation element (7) for modulating light having a linear polarization and emitted from a laser light source (1), and a depolarization means (21) for depolarizing the modulated light before it is incident on an image display surface. The light having a linear polarization is used before and after incidence of irradiated light to the spatial light modulation element (7), and the linear polarization of the irradiated light is depolarized after the modulation, whereby randomly polarized light is projected on a screen (11). Thereby, speckle noise is significantly reduced, and a high-definition image can be formed.

Abstract: After forming domain inverted layers 3 in an LiTaO3 substrate 1, an optical waveguide is formed. By performing low-temperature annealing for the optical wavelength conversion element thus formed, a stable proton exchange layer 8 is formed, where an increase in refractive index generated during high-temperature annealing is lowered, thereby providing a stable optical wavelength conversion element. Thus, the phase-matched wavelength becomes constant, and variation in harmonic wave output is eliminated. Consequently, with respect to an optical wavelength conversion element utilizing a non-linear optical effect, a highly reliable element is provided.

Abstract: After forming domain inverted layers 3 in an LiTaO3 substrate 1, an optical waveguide is formed. By performing low-temperature annealing for the optical wavelength conversion element thus formed, a stable proton exchange layer 8 is formed, where an increase in refractive index generated during high-temperature annealing is lowered, thereby providing a stable optical wavelength conversion element. Thus, the phase-matched wavelength becomes constant, and variation in harmonic wave output is eliminated. Consequently, with respect to an optical wavelength conversion element utilizing a non-linear optical effect, a highly reliable element is provided.

Abstract: A holographic optical information recording/reproducing device is provided with a laser light source 1 and a polarizing beam splitter 8 for splitting a light from the laser light source 1. At the time of recording information, one of light beams split by the polarizing beam splitter 8 is modulated by a spatial light modulating element 2 to form a beam array, which becomes a signal light 25, whereas the other split light beam becomes a reference light 22. Interference fringes generated by the signal light 25 and the reference light 22 are recorded as holograms in a holographic disc 5. At the time of reproducing the information, only the reference light 22 is irradiated to the holographic disc 5 and its diffracted light is detected.

Abstract: After forming domain inverted layers 3 in an LiTaO.sub.3 substrate 1, an optical waveguide is formed. By performing low-temperature annealing for the optical wavelength conversion element thus formed, a stable proton exchange layer 8 is formed, where an increase in refractive index generated during high-temperature annealing is lowered, thereby providing a stable optical wavelength conversion element. Thus, the phase-matched wavelength becomes constant, and variation in harmonic wave output is eliminated. Consequently, with respect to an optical wavelength conversion element utilizing a non-linear optical effect, a highly reliable element is provided.

Abstract: In a display device that displays a video by scanning coherent light across a screen, modulation at high speeds and gradation are necessary for a coherent light source. An oscillation wavelength of a semiconductor laser outputting the fundamental wave is changed at high speeds through the plasma effect induced by applying a pulse current to the coherent light source. A change of the wavelength causes the output of a higher harmonic generated in a light wavelength conversion element to change, and gradation is produced using such a change.

Abstract: A louver apparatus includes a case member, a connecting member, and a louver pivotally secured to the case member, including a shaft portion including a shaft body being in the form of a substantially cylindrical shape, and a head portion being in the form of a substantially regular polygon, and being located at a tip end portion of the shaft body. At least a part of the head portion protruding radially from the shaft body. The connecting member includes an axial hole being in the form of a substantially regular polygon. The head portion is arranged to pass through the axial hole only at predetermined positions, and to be held not to pass through the axial hole at positions other than the predetermined positions.

Abstract: There is provided a coherent light source including: a light source unit having a dope fiber and emitting a light of first wavelength and a light of second wavelength by the dope fiber; and a wavelength conversion element unit having a first wavelength conversion element for receiving the light of the first wavelength and emitting a light having a wavelength shorter than the first wavelength.

Abstract: After forming domain inverted layers 3 in an LiTaO3 substrate 1, an optical waveguide is formed. By performing low-temperature annealing for the optical wavelength conversion element thus formed, a stable proton exchange layer 8 is formed, where an increase in refractive index generated during high-temperature annealing is lowered, thereby providing a stable optical wavelength conversion element. Thus, the phase-matched wavelength becomes constant, and variation in harmonic wave output is eliminated. Consequently, with respect to an optical wavelength conversion element utilizing a non-linear optical effect, a highly reliable element is provided.

Abstract: An optical element is provided that includes a base substrate, a waveguide substrate, and a thin film layer that is provided between the base substrate and the waveguide substrate and that has a single-layer structure of a multilayer structure including a film containing Ta2O5 or Nb2O5 as a principal component.

Abstract: In the video projector of the present invention, a fiber part (3b) of a fiber laser (3) is disposed so as to draw a circulating orbit of more than one circulation along the inner wall of the projector housing (1). Further, an FBG (14) which constitutes the fiber laser (3) is fixed so that its shape is not changed. Furthermore, a pump LD part (3a) of the fiber laser (3) is disposed apart from the SHG element (5). As a result, the video projector can be miniaturized, and thereby the portability and installment of the video projector are facilitated. Further, the output stabilization of the fiber laser can be realized by preventing the shape change of the FBG. Furthermore, by disposing the SHG element apart from the pump LD part which forms a heat source, the temperature change of the SHG element is suppressed and the wavelength conversion efficiency by the SHG element is enhanced.