Abstract: An optical disc drive using either one of a first disc (e.g., DVD) and a second disc (e.g., CD), is provided with a first laser diode that emits a shorter wavelength beam, a second laser diode that emits a longer wavelength beam, an objective lens, and a driving unit that holds and rotates the optical disc. The optical axis of the objective lens is inclined relative to a normal to the optical disc. The first laser diode is located at a first position so that the coma, which is caused when the first laser beam is converged on a data recording surface of the first disc, is minimized, and the second laser diode is located at a second position so that the coma, which is caused when the second laser beam is converged on a data recording surface of the second disc, is minimized.

Abstract: A liquid crystal light valve includes a semiconductor substrate having a region for a plurality of switching elements formed in a matrix form. A first metal layer is formed on the surface of the semi-conductor substrate through an insulating layer and divided into a plurality of parts by first slits. A second metal layer is formed on the first metal layer through another insulating layer and divided into a plurality of parts by second slits. A third metal layer is formed on the second metal layer through still another insulating layer and divided into a plurality of parts by third slits. An opposite substrate has an opposite electrode on a surface thereof, disposed so as to be opposite to said third metal layer through an interval on the opposite electrode side. Liquid crystal fills the interval between said opposite electrode and the third metal layer.

Abstract: An objective lens converges a shorter wavelength laser beam on a DVD having a protective layer, which is 0.6 mm thick, and a longer wavelength laser beam on a CD having a protective layer, which is 1.2 mm thick. A common region is defined on the objective lens. The common region provides a numerical aperture appropriate for converging the longer wavelength laser beam on the CD. Coma of the objective lens in the first region is compensated better in a case where the longer wavelength laser beam is converged on the CD than a case where the shorter wavelength laser beam is converged on the DVD.

Abstract: An objective lens and an optical head including the objective lens for reading information contained on substrates having different thicknesses using laser beams having different wavelengths. The objective lens includes an annular phase shifter for decreasing an aberration of a focused spot of each of the laser beams. The annular phase shifter can be optimally combined with the objective lens having inner and outer regions each having a different substrate thicknesses.

Abstract: An objective lens and an optical head including the objective lens for reading information contained on substrates having different thicknesses using laser beams having different wavelengths. The objective lens includes an annular phase shifter for decreasing an aberration of a focused spot of each of the laser beams. The annular phase shifter can be optimally combined with the objective lens having inner and outer regions each having a different substrate thicknesses.

Abstract: An objective lens and an optical head including the objective lens for reading information contained on substrates having different thicknesses using laser beams having different wavelengths. The objective lens includes an annular phase shifter for decreasing an aberration of a focused spot of each of the laser beams. The annular phase shifter can be optimally combined with the objective lens having inner and outer regions each having a different substrate thicknesses.

Abstract: A color liquid crystal display device includes a liquid crystal element, an optical path conversion element array and a hologram. The liquid crystal element has a blue pixel B, a red pixel R, and a green pixel G, which are arranged plainly, and a liquid crystal layer. The optical path conversion element array converts external light into approximately parallel light. The hologram separates light from the optical path conversion element array into a light having a wavelength range of the three primary colors and irradiates pixels R, G and B corresponding to the liquid crystal element.

Abstract: A laser printer is provided printing with a high precision simply and at a high speed, and the laser printer uses a semiconductor laser which can vary the diameter of the emitted light while the light density is held constant. In the laser printer, laser rays emitted from a semiconductor laser are irradiated onto a photoconductor to vary its surface potential to produce a charge pattern particles adhere, and printing is performed by transferring the changed particles to a printing object. The semiconductor laser has a plurality of waveguide type resonators, the emitted beams of the resonators having a spatial superposition, and light emission is possible so that the emitted beams of the resonators having a spatial superposition with respect to each other among the resonators of the semiconductor laser are not substantially superimposed in time.

Abstract: A directional reflection screen includes a corrugated mirror sheet constituted by a plurality of mirrors, and a lens sheet for diffusing and reflecting rays of light in the direction of ridge lines of the corrugated mirror sheet. The ridge lines of the corrugated mirror sheet intersect the lens lines of said lens sheet at angles other than 90.degree.. The projection display further includes projection means for projecting an image onto the directional reflection screen.

Abstract: A laser beam printer is provided which is capable of compensating for the difference in diameter between dots every colors and preventing unintentional coloring of the boundary between colors. In a conventional light source used for a printer, a spot diameter thereof is small upon low output and large upon high output. However, in a semiconductor laser device of the present invention, which is used for a light source for a printer, the spot diameter of the light source is controlled so as to be large upon low output and small upon high output. It is thus possible to keep the spot diameter of the laser light source constant. As a result, an irregular color-free laser beam printer can be materialized.

Abstract: A liquid crystal light valve includes a semiconductor substrate having a region for a plurality of switching elements formed in a matrix form. A first metal layer is formed on the surface of the semiconductor substrate through an insulating layer and divided into a plurality of parts by first slits. A second metal layer is formed on the first metal layer through another insulating layer and divided into a plurality of parts by second slits. A third metal layer is formed on the second metal layer through still another insulating layer and divided into a plurality of parts by third slits. An opposite substrate has an opposite electrode on a surface thereof, disposed so as to be opposite to said third metal layer through an interval on the opposite electrode side. Liquid crystal fills the interval between said opposite electrode and the third metal layer.

Abstract: A light beam scanning apparatus in which laser power and spot shape of an emitted laser beam are controlled, has a laser control signal generating part for changing a picture signal to a laser power control signal and a spot shape control signal, a laser power control current generating part which is driven by the laser power control signal, a spot shape control current generating part which is driven by the shape control signal, and a laser beam emission part for emitting a laser beam having a laser power and a spot shape which are controlled by the control signals via a commonly used light wave guiding part, wherein the control signal generating part generates or corrects the control signals based on at least one of the difference between the laser power of a beam to be emitted and a detected laser power, the difference between the spot shape of a beam to be emitted and a detected laser power, a detected temperature at the laser beam emission part, and an effective light emission pixel number.

Abstract: In an optical head, light from a semiconductor laser is directed through a condensing optical system with a condensing lens onto an optical information recording medium through a transparent substrate in the form of a light spot. A unit for producing a light spot position control signal and a unit able to move the light spot, which supports the objective lens for movement, position the light spot on an information track. Light reflected from the optical information recording medium is directed through a polarized light branching element to a photo detector.

Abstract: The objective lens has a numerical aperture NA=0.6 when reproducing a DVD having a thickness of 0.6 mm and NA=0.42 when reproducing a CD having a thickness of 1.2 mm. At a boundary of NA 0.42, a slight stepped portion is formed so as to establish a phase difference. In this case, a designed wavelength is 0.635 .mu.m, and an optimum designed substrate thickness of a central portion is approximately 0.8 mm. While the DVD is reproduced, wave front aberration is on the order of 0.025.lambda., and jitter contained in the reproduction signal of the CD is equivalent to the present jitter. As a consequence, such an objective lens and an optical head with employment of this objective lens are provided, which precisely reproduce signals from the CD having the substrate thickness of 1.2 mm, and the DVD having the substrate thickness of 0.6 mm.

Abstract: A reflective liquid crystal display apparatus has a liquid crystal display part composed of at least a liquid crystal layer and a pair of polarizers holding the liquid crystal layer therebetween, for display of bright and dark states in a mode of transmitting and shielding external light in a direction approximately normal to a display plane, and a reflecting part for reflecting the external light which has been transmitted through the liquid crystal display part. The liquid crystal display part has a property where it can transmit external light in a designated direction other than in a direction approximately normal to the display plane even in a mode of shielding the external light, and the reflecting part reflects the external light received in the designated direction so as to transmit the external light once again through the liquid crystal display part in a direction approximately normal to the display plane.

Abstract: A semiconductor laser device is disclosed, in which two semiconductor layers of different conduction types are formed on a semiconductor substrate, an active semiconductor layer having a forbidden band width narrower than the two semiconductor layers is formed between the two semiconductor layers, and a waveguide encloses the light in a plane parallel to the active layer. The waveguide includes at least two regions of different widths. The wider one of the waveguide regions is located in the vicinity of the end surface of the semiconductor laser. A relation holds that .pi./6<L.times.(K.sub.0 -K.sub.2) <.pi..times.5/6, where L is the length of the wider waveguide region, and K.sub.0, K.sub.2 are propagation constants of the zeroth-order and second-order transverse modes, respectively, propagating in the waveguide.

Abstract: An optical arrangement for an optical scanning apparatus which can record a plurality of high precision information concurrently, provides for a laser beam emitted from a single light source to be polarized in two polarization directions, and each of the two polarized beams is further imparted with different information according to its polarization direction. Then, the two polarized beams are used for scanning over a photosensitive member to concurrently record respective information at different positions on the photosensitive member. In order to suppress induced light fluctuation depending on an incident angle of light on the beam splitter, an optical rotation means is provided in the optical system, such that a desired optical rotation control can be obtained corresponding to the incident angle on the beam splitter, so as to compensate for the fluctuation of light whereby the beam splitter can be arranged to be free of the influence of the incidence angle of the beam.

Abstract: A high-speed image forming method and apparatus is capable of directly controlling a toner by the force of an energy beam. Selected toner particles in a mass of toner adhering to the surface of a transparent drum are irradiated with a laser beam emitted by a laser disposed within the transparent drum and controlled for scanning according to image information. The laser beam separates the selected toner particles from the transparent drum by the force it produces on the particles, and then the separated toner particles are moved to a paper sheet by the force of an electric field produced by a developing electrode. Each toner particle need only be irradiated with the light for a comparatively short period of time, so that an image can be formed at high speed.

Abstract: An information indicator suitable for information processors such as personal computers, word processors and the like includes a light source, a scattering plate which scatters light from the light source, an indicator plate irradiated with scattered light from the scattering plate, and a prism plate operatively arranged with respect to the scattering plate and the indicator plate and having a prism-like protuberance structure formed at a side thereof. The prism plate is so disposed that the prism-like protuberance structure faces the scattering plate, and the angle 2.theta. constituting the prism-like protuberance structure is defined by the formula, 2.theta..ltoreq.2/3.times.(.pi./2+2.times.arcsin (n'/n)), in this inequality, n is the refractive index of said prism plate medium, and n' is the refractive index of a material in which the prism plate is arranged.

Abstract: In a laser printer wherein a photoconductive drum is scanned by utilizing a plurality of laser beams, there are detected spacings between the plural laser beams, such detection being confined to a blanking time. On the basis of the detected results, the spacings between the plural laser beams are controlled; and this state is maintained for a printing time. With this arrangement, it is possible to accurately detect the spacings between the plural laser beams thereby to obtain the practicable laser printer employing the plural laser beams.