Abstract: A lens device for focusing a beam of an ultraviolet-ray region, provided with at least one aspherical lens made of synthetic quartz in which an aspherical portion is formed by a coating a fluororesin on a spherical portion of a side polished to a spherical surface; an ultraviolet-ray emitting device provided with a laser beam source emitting a beam in the ultraviolet-ray region and an object lens which has at least one of the above aspherical lenses; and an optical disc recording device provided with a laser beam source emitting a beam in the ultraviolet-ray region, a light intensity modulating means for modulating the intensity of the laser beam emitted from the laser beam source in accordance with a data signal; and the above object lens.

Abstract: An optical pickup device for condensing the light from a light source on a signal recording surface by an objective lens and for detecting the return light from the signal recording surface by a light detection unit is disclosed. The optical pickup device is capable of recording and/or reproducing at least two different sorts of optical recording media. The light beam radiated from a light source is condensed by an objective lens. An aperture varying unit varies the size of an aperture of the objective lens depending upon the sorts of the optical recording media. The return light from the optical recording medium is detected by a light detection unit. The size of the aperture of the objective lens for condensing the light from the light source is varied depending upon the difference in substrate thickness of the different sorts of the optical recording media, thus assuring high-quality recording/reproduction for two or more different sorts of optical recording media.

Abstract: An optical pick-up apparatus includes a light source, an objective lens, a beam splitter, a detector, a first optical compensating device and a second optical compensating device. The objective lens converges a light beam emitted from the light source at one point on an optical axis. The beam splitter separates the light beam emitted from the light source from a returning light reflected on an optical disc. The detector detects the returning light separated from the light beam emitted from the light source. The first optical compensating device has a convex aspherical surface represented by X.alpha.R.sup.4 and is located on an optical path where the light beam is emitted from the light source. The second optical compensating device has a concave aspherical surface represented by +.alpha.R.sup.4 and is located on an optical path where the light beam is emitted from the light source.

Abstract: An optical pickup apparatus for irradiating a light beam on an optical recording medium for recording or reproduction, including a light source, an objective lens, a nonpolarization beam splitter, a photodetector, and a 1/4 wavelength plate. The objective lens focuses the light beam radiated from the light source on to the recording layer of the optical recording medium. The nonpolarization beam splitter is disposed between the objective lens and the light source and separates the light beam emitted from the light source and the light beam reflected by the recording layer of the optical recording medium. The photodetector receives the beam of light reflected by the recording layer of the optical recording medium which has been separated by the nonpolarization beam splitter and deflected 90.degree. in optical path. The 1/4 wavelength plate is disposed on the path of emission of the light beam emitted from the light source between the nonpolarization beam splitter and the optical recording medium.

Abstract: A disc reproducing apparatus such ah as video disc players and compact disc players, etc., surely corrects skew of an optical disc and reproduces recorded information even though the recording density is high. The disc reproducing apparatus has a plate-like transparent member interposed in a focused light path of the light beam so as to tilt the transparent member and cancel any comatic aberration. A light spot correction means having the transparent parallel flat plate and at least a coil and a magnet changing the inclination of the flat plate is arranged in a light path of a light beam, thus comatic aberration due to skew of the optical disc is surely and simply corrected.

Abstract: A laser light beam generating apparatus includes at least one light beam source, first and second reflectors, a non-linear optical crystal element and an actuator. The light beam source emits a light beam. The non-linear optical crystal element is provided between the first reflector and the second reflector. A light beam emitted from the light beam source is incident on the non-linear optical crystal element through the first reflector. The actuator actuates at least one of the first and second reflectors along an optical axis of the light beam emitted from the light beam source.

Abstract: A method for the optical axis of an optical pickup apparatus includes the step of adjusting the optical axis of a beam expander for enlarging the diameter of a light beam outgoing from a laser light beam radiating device into coincidence with the optical axis of the light beam radiated from the laser light beam radiating device. The laser light beam radiating device includes a non-linear optical crystal element and is adapted for radiating a second harmonic laser light beam. The method also includes the step of mounting the beam expander having adjusted its optical axis, and a step of adjusting, with the beam expander mounted on the laser light radiating device, the optical axis of an optical system converging the laser light beam radiated from the laser light beam radiating device so that the optical axis is brought into coincidence with the optical axis of the laser beam radiated from the laser light beam radiating device.

Abstract: A laser light beam generating apparatus includes at least one light beam source, first and second reflectors, a non-linear optical crystal element and an actuator. The light beam source emits a light beam. The non-linear optical crystal element is provided between the first reflector and the second reflector. A light beam emitted from the light beam source is incident on the non-linear optical crystal element through the first reflector. The actuator actuates at least one of the first and second reflectors along an optical axis of the light beam emitted from the light beam source.

Abstract: An optical pickup head apparatus comprises a yoke provided in an opposing relation to a magnet, a movable member having formed therethrough an aperture into which the yoke is inserted and around which a first coil is wound in an opposing relation to the magnet, an object lens supporting device having a pair of leaf springs for supporting the objective lens so that the objective lens can move in the direction parallel to the optical axis thereof and a plurality of second coils of substantially square shape for moving the objective lens in the direction parallel to the optical axis thereof and a tracking control device for rotating a mirror portion so that a beam spot focused on the optical disc by the objective lens follows a track on the optical disc, wherein the objective lens supporting device is secured to the movable member, the movable member is movably supported by the yoke and sides of the second coils which cross the optical axis of the objective lens and the first coil are located within a common mag

Abstract: A laser beam generator for making wavelength conversion automatically controls the length of an external resonator of a laser source to perform wavelength conversion at a high efficiency by pulling-in a servo using a resonator length error signal and a reflected light signal. A sample-and-hold circuit is used to detect the error signal from the detected light signal which is reflected from the external resonator.

Abstract: A laser light beam generating apparatus includes at least one light beam source, resonator and an optical system. The resonator generates a type II second harmonic laser light beam. The resonator has a first reflector, a second reflector, a laser medium provided between the first and second reflectors and irradiated a light beam emitted from the light beam source through the first reflector and a non-linear optical crystal element provided between the laser medium and the second reflector. The optical system radiates the type II second harmonic laser light beam emitted from a virtual luminance point of the resonator to a conjugate point. In this laser light beam generating apparatus, with an effective length of the resonator L, an effective distance Le from the resonator to the conjugate point is set to thatLe=(m+1/2)Lwhere m is an integer.

Abstract: A control circuit for an inverter for converting DC voltage to AC voltage, operable in an individual mode and an interconnection mode, and including a synchronous compensating circuit in which, when the inverter is operating in a power system synchronous operation mode under control of a synchronous-interconnection control system, a quantity of an instantaneous voltage variation component occurring in the power system is separated, in order to detect respectively, a quantity of the variation of the component in same phase with a reference voltage vector of the output voltage of the inverter, and a quantity of the variation of the component orthogonal to the reference voltage vector. The detected variation quantities are respectively added to the outputs of a voltage adjuster and a phase adjuster in the synchronous-interconnection control system. The circuit is capable of compensating an instantaneous variation of the power system without a decrease of circuit stability.

Abstract: A recording and/or reproduction apparatus of an optical disc having recording tracks in which mirror areas are formed incorporates an optical head for recording or reproducing information signal onto or from the optical disc which has an optical detector for detecting a tracking error signal by a push-pull method; a fine actuator for precisely actuating the optical head finely; detecting means for detecting an output signal of the optical detector responding to reflected light from the mirror area; and driving means for driving the fine actuator in response to an output signal of the detecting means during the seeking operation.

Abstract: The method of the present invention comprises detecting a recording pattern, which is different for each tract, in each of track groups consisting of a predetermined number N or tracks recorded in advance on an optical disk(1), generating a tracking signal S.sub.ET whose signal level changes on the positive and negative sides of a target track T.sub.0 as the center, and moving the optical spot to the target track T.sub.0 on the basis of this tracking signal S.sub.ET. In this manner, it becomes possible to prevent uncontrollable movement of the optical spot and align the optical spot to a desired recording track within a short period of time.

Abstract: A rotation control for a magnet used in a magneto-optical recording system having a first coil that rotates a permanent magnet to invert the polarity of its magnetic field applied to an optical recording type disc and a second coil provided at the position displaced from the central line of the first coil and for applying a driving force to the permanent magnet when the permanent magnet begins to rotate, wherein the permanent magnet can be settled in quite a short time after it is inverted in polarity by controlling a drive current applied to the second coil.

Abstract: A moving coil type linear motor in which yokes disposed opposite to magnets magnetized in the thickness direction thereof penetrate through-holes of a bobbin on which a coil is wound that is energized to generate the magnetic flux which intersects the magnetic flux of the magnets, and the bobbin is moved along the yokes by energizing the coil, wherein a guiding portion for guiding a rolling element including balls, for example, is provided in the surfaces of the respective yokes which do not face the magnets and the through-holes of the bobbin, to thereby support the bobbin on the yokes through the rolling elements.

Abstract: A tracking servo system in a recordable optical disk player apparatus utilizes clock signals to be produced by irradiating laser beam to clock pits in servo areas as a reference signal for on-track adjustment. Based on the clock signal, polarity of a tracking error signal is detected for selectively opening and closing servo loop of the tracking servo system. CLOSED LOOP on-track adjustment will be performed while a laser beam spot is in a range where the tracking error indicative value is gradually reduced according to decreasing of the distance of the laser beam spot to the track center. On the other hand, OPEN LOOP on-track adjustment will be performed while the laser beam spot is in a range where the tracking error indicative value is increased according to decreasing of the distance between the laser beam spot and the track center.

Abstract: A focusing control method and apparatus employing a photodetector for generating a focusing error signal, a tracking error signal and an RF signal, and a closed loop focusing servo circuit responsive to the focusing error signal applied thereto for focusing a light spot in position on an optical disc. The focusing error signal is detected synchronously with the tracking error signal to produce a first periodic function signal. The focusing error signal is detected synchronously with the RF signal to produce a second periodic function signal. The tracking error signal is converted into a sin-wave signal having a predetermined amplitude. The RF signal is converted into a cos-wave signal having a predetermined amplitude. The first periodic function signal is multiplied by the cos-wave signal to produce a first component signal. The second periodic function signal is multiplied by the sin-wave signal to produce a second component signal.