Abstract: A GaN-based semiconductor laser (1) emits first laser light of a single polarization and having a first wavelength. An optical resonator (30) includes a solid-state laser medium which is excited by incidence of the laser light and which oscillates second laser light having a second wavelength different from the first wavelength. A polarization switch (6) switches over at least one of polarization directions of the first laser light and the second laser light to thereby change the wavelength of laser light to be emitted from the optical resonator (30) or the intensity ratio between a plurality of laser light to be emitted from the optical resonator (30). With the above arrangement, a plurality of laser light can be used effectively.

Abstract: A projector has: light source (1R, 1G, 1B); a light modulation unit (6) that modulates a light emitted from the light source based on image signals; a display control unit (41) that outputs the image signals including main cyclic image signals to the light modulation unit, and controls the display thereof; a projection unit (7) that projects the image based on the light modulated by the light modulation unit; and an imaging unit (40) that captures an image to be displayed based on the light projected from the projection unit, and the display control unit inserts a correction image signal for projecting a correction image, which is visually recognized as a uniform white or gray screen when time integration is performed, between the cyclic main image signals.

Abstract: A liquid crystal display device includes a reflective color filter arranged to intersect with an optical path of light emerging from a principal surface of a light guide plate, and a recycle portion arranged at a side of the light guide plate opposite to the reflective color filter. Out of light incident on the light guide plate, light reflected by the reflective color filter is returned to the reflected color filter again by being reflected by the recycle portion via the light guide plate.

Abstract: A compact liquid crystal display device is provided by connecting a plurality of liquid crystal display panel units each provided with a light guiding plate unit on a back side with a connection portion and supplying a laser light source via the connection portion. The compact liquid crystal display device includes a plurality of display portions formed of liquid crystal display panel units and light guiding plate units disposed in intimate contact with the back sides of the liquid crystal display panel units, a connection portion connecting a plurality of the display portions, and a laser light source. By supplying a laser beam emitted from the laser light source to the light guiding plate units via the connection portion, the display surfaces of the liquid crystal display panel units are illuminated by the laser beam.

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: Provided is a planar illuminating device having light source section (1) emitting linearly polarized laser light and having a light guide (12) with a rectangular parallelepiped shape having one main surface with a mirror array (12c) thereon. The mirror array (12c) has a plurality of reflecting surfaces totally reflecting laser light incident on an incident surface (12a), of the light guide, perpendicular to the one main surface and emits the laser light from an emitting surface (12b), of the light guide, perpendicular to the one main surface, wherein the reflecting surfaces are formed in a stepped manner. Further, the planar illuminating device includes a light-guiding plate (3) making the laser light, emitted from the light guide (12), incident on an incident surface (3a) of the light-guiding plate and emitting the laser light from an emitting surface (3b) of the light-guiding plate.

Abstract: A planar illumination device is provided with a plurality of light guide paths, on which scanned light in different scanning sections of a scanning range by a scanning unit is respectively incident, and an illumination unit having a plurality of emission regions for emitting the light guided by the respective light guide paths. The number of the emission regions is 2 or more and 1000 or less, and the respective emission regions successively become luminous as the scanned light is incident on the respective light guide paths.

Abstract: A laser light source includes a semiconductor laser, a wavelength converting element made of a non-linear optical crystal for converting excitation light from the semiconductor laser into wavelength converted light having a wavelength different from the wavelength of the excitation light, a photodiode for measuring a part of the wavelength converted light to be emitted from the wavelength converting element as output light, a photodiode for measuring the excitation light to be emitted from the wavelength converting element, and a control circuit, wherein the control circuit simultaneously performs an output constant control of making the intensity of the wavelength converted light constant, using a current driving circuit, and a temperature control of adjusting the temperature of the wavelength converting element, using a heater.

Abstract: A laser emission device comprises a plurality of laser elements, a plurality of laser driving power supplies, optical elements which uniformize the laser light amount distributions of laser lights, plural light-receiving elements, a measurement unit which measures at least the relations between the operation current values of the laser elements and the output power values of the laser lights with respect to the operation current values, and the control unit operates the laser driving power supplies according to the operation current values and the output power values so as to make the light output powers of the laser elements different from each other.

Abstract: A planar illumination device 10 is provided with a laser light source 11 for emitting laser light, a light source side bundle fiber 12 having one end surface thereof optically connected with the laser light source 11, a flat light guide plate 13, a plurality of connection side fibers 16 planarly arranged in parallel with each other at a side surface of the light guide plate 13, and a light guiding fiber 14 for guiding the laser light from the light source side bundle fiber 12 to the plurality of connection side fibers 16. The laser light is incident on the side surface of the light guide plate 13 from the plurality of connection side fibers 16 via a plurality of fiber collimators 17 and output light is uniformly emitted from one principal surface of the light guide plate 13.

Abstract: A laser light source (1) emits a beam. A collimator lens (2) converts the beam emitted from the laser light source (1) into first substantially parallel light. A lenticular lens (3) expands a beam of the first substantially parallel light converted by the collimator lens (2) into a linear shape in a first direction. A Fresnel lens (4) converts the beam expanded in the first direction by the lenticular lens (3) into second substantially parallel light. A free curved surface mirror (5) has a reflecting surface formed into a free curved surface, and expands a beam of the second substantially parallel light converted by the Fresnel lens (4) into a planar shape in a second direction orthogonal to the first direction. This arrangement enables to provide a planar illumination device with a small thickness and high light use efficiency.

Abstract: A display device (100) of the present invention has a first switch (3) and a second switch (4) on an upper surface of its casing, and includes a control circuit (18) for controlling the first switch (3) and the second switch (4) and a light source (19) inside the casing. The control circuit (18) performs control so that the light source (19) is turned on when the second switch (4) is pressed after a predetermined period of time has passed from when the first switch (3) was pressed. Thereby, the display device (100) of the present invention prevents entering of a person into a projection area before projection of video, and controls inadvertent start-up.

Abstract: A wavelength converter is provided with an infrared light source (1) for emitting a fundamental wave having a wavelength of 2000 nm or shorter, a wavelength conversion element (3) composed of a nonlinear optical crystal having a periodical polarization reversal structure and adapted to convert a fundamental wave emitted from the infrared light source (1) into a harmonic wave, and a heater (4) for heating the wavelength conversion element (3). The period of the polarization reversal structure is designed so that a quasi phase matching temperature of the fundamental wave and the harmonic wave is 40° C. or higher. The heater (4) heats the wavelength conversion element (3) to a temperature at which quasi phase matching is established, and the nonlinear optical crystal contains a lithium niobate or lithium tantalate including at least any one of additives Mg, In, Zn and Sc as a main component. Thus, optical damage can be suppressed and visible light absorption attributed to ultraviolet light can be reduced.

Abstract: Upon obtaining green light as wavelength converted light by causing infrared light to be incident on a wavelength conversion element, the absorption of the green light occurs due to the generation of ultraviolet light as sum-frequency light of the infrared light and the green light in the wavelength conversion element and the destruction of a crystal composing the wavelength conversion element occurs due to heat generated at this time. In a laser wavelength converter of the present invention, a condensed position of the infrared light in the wavelength conversion element is deviated from a position assumed to be optimal when the influence of the generated heat is ignored. Consequently, crystal destruction is suppressed, a high-efficiency wavelength conversion is enabled and high-output wavelength converted light exceeding several watts, which was difficult to attain in conventional wavelength conversion elements, is attained.

Abstract: A wavelength conversion laser light source includes: an element temperature switching section that switches a temperature of the wavelength conversion element according to a harmonic wave output value as set in an output setting device, and the element temperature switching section for switching a temperature of a wavelength conversion element according to a harmonic wave output level as set in the output setting device, wherein the element temperature switch section includes an element temperature holding section that holds the wavelength conversion element at the temperature as switched by the element temperature switching section.

Abstract: A planar illumination device for illuminating a liquid crystal display panel provided with a polarizing plate on a light incident side, includes: a light source unit for emitting light having a specified polarization direction; and a light irradiating member for deflecting light emitted from the light source unit and irradiating the liquid crystal display panel with the deflected light, wherein the light irradiating member deflects the light emitted from the light source unit such that the polarization direction of the light emitted from the light source unit substantially coincides with a transmission axis direction of the polarizing plate of the liquid crystal display panel.

Abstract: A display for illuminating a liquid crystal display panel with laser light of uniform light quantity distribution, and an illuminator for irradiating with laser light of uniform light quantity distribution. The display includes a liquid crystal display panel (204), laser light sources (205, 206, 207) emitting laser light having wavelengths of green, red, and blue colors, a waveguide plate (201) arranged at the back side of the liquid crystal display panel (204) and performing multiple reflection of laser light, and a diffusion plate (202) arranged at the back side of the waveguide plate (201), diffusing laser light propagating in the waveguide plate (201) and emitting the light toward the liquid crystal display panel (204).

Abstract: A laser light source device, which is capable of multi-wavelength oscillation, includes a laser light source; and a laser cavity including (i) a fiber, (ii) a first fiber grating provided at a side of the fiber toward the laser light source and having a plurality of reflection peaks, and (iii) a second fiber grating provided at a light emission end of the fiber and having a plurality of reflection peaks. Further, the laser light source includes a wavelength converter converting a fundamental wave emitted from the laser cavity into a harmonic wave; a reflection wavelength varying unit shifting reflection wavelengths of the reflection peaks of the second fiber grating; and a controller controlling phase matching conditions of the wavelength converter. As a result, intervals between adjacent reflection peaks of the first fiber grating are different from those between adjacent reflection peaks of the second fiber grating.

Abstract: A 2-dimensional beam scan unit reflects emission beams from a red laser light source, a green laser light source and a blue laser light source and scans in a 2-dimensional direction. Diffusion plates diffuse the respective light beams scanned in the 2-dimensional direction to introduce them to corresponding spatial light modulation elements. The respective spatial light modulation elements modulate the respective lights in accordance with video signals of the respective colors. A dichroic prism multiplexes the lights of the three colors after the modulation and introduces the multiplexed lights to a projection lens so that a color image is displayed on a screen. Since the 2-dimensional light emitted from the beam scan unit is diffused to illuminate the spatial light modulation element, it is possible to change the optical axis of the beam emerging from the light diffusion member for irradiating the spatial light modulation element moment by moment, thereby effectively suppressing speckle noise.

Abstract: A wavelength conversion laser device includes a laser light source which emits a laser beam, two reflective surfaces which reflect therefrom a laser beam, a wavelength converter provided between the two reflective surfaces, which converts a laser beam into a wavelength-converted laser beam, and condensing optics which condense the laser beams to be injected between the two reflective surfaces, wherein at least one of the two reflective surfaces has a curvature for reflecting a laser beam to be re-injected into the wavelength converter between the two reflective surfaces repeatedly while forming multi paths of laser beams injected into the wavelength converter at different incident angles, and the condensing optics are arranged to disperse beam waists of the laser beams in the wavelength converter, which reciprocate between the two reflective surfaces.