Abstract: Detecting the rotational direction of a rotor is feasible by allowing a constant current source to supply a constant current flowing from an electric potential supply line to the earth in response to a turning-on action of a switch. Accordingly, detecting both the rotational speed and the rotational direction of the rotor is feasible by using three wiring cables of a power source line, an earth line, and a signal line outputting a pulse signal in accordance with the rotation of the gear. Using such a one-stage voltage adjustment enables the detection signal processing circuit to reduce electric power consumption compared with a system requiring a two-stage voltage adjustment.

Abstract: A holographic recording/reproducing apparatus includes a splitter unit for splitting a laser beam into a first laser beam for generating a signal beam and a second laser beam which serves as a reference beam, a spatial light modulator for spatially modulating the first laser beam in accordance with information to be recorded, the modulated first laser beam serving as the signal beam, and a first lens system for focusing the signal beam and the reference beam onto a holographic recording medium. In a recording process, the signal beam and the reference beam are guided through one and the other half-regions separated along the optical axis of the first lens system. In a reproduction process, only the reference beam is guided through one of the half-regions and a signal reproduction beam from the holographic recording medium is guided through a second lens system in the other half-region.

Abstract: A hologram recording apparatus, a hologram recording method and a hologram recording medium reduce noise components generated by a phase modulation type spatial light modulator, thus permitting improved integrity of data to be achieved. A light beam whose diffraction state has been controlled by a diffraction control element is condensed on a hologram recording medium. With this arrangement, a predetermined diffracted light component is removed from a diffracted light beam emergent from the diffraction control element when recording information, which is based on the diffraction state controlled by the diffraction control element, in a hologram recording medium. Thus, noise components when information is recorded can be reduced.

Abstract: In an apparatus and method for optically recording on an optical disk a television signal comprised of a color image signal and an audio signal; one horizontal period portion of an original luminance signal and one horizontal period portion of two original color difference signals from a standard television signal are time-base-compressed to generate a time-base-compressed video signal for one horizontal period, the audio signal is digitized and time-base-compressed, and then the time-base-compressed digital audio signal and the time-base-compressed video signal are time-division-multiplexed with each other and recorded on the optical disk.

Abstract: This invention relates to an anamorphic prism (11) for correcting an anisotropy of a radiation angle of a beam (14). The anamorphic prism (11) is constituted by a first prism (12) and a second prism (13) so that tha anamorphic prism (11) can have an achromatic structure. Refractive indexes and refractive index changes due to a wavelength fluctuation of the first and second prisms (12, 13), and an incident angle of the beam (14) to the first prism (12) can satisfy a predetermined relationship, and the beam (14) can be emerged from the second prism (13) at an exit angle of 0.degree.. The anamorphic prism of this invention can be applied to an optical head or the like using a semiconductor laser as a light source.

Abstract: In a recording/reproducing optical system of the invention, which comprises a semiconductor laser causing single transverse mode oscillation and having beam radiation angles of .theta..perp. and .theta..parallel. in planes normal and parallel to an active layer, respectively; a collimator lens having a focal length f.sub.c ; an anamorphic optical element having a magnification ratio of 1:.beta. in two directions crossing each other at right angles; and an objective lens having a focal length f.sub.0, a numerical aperture NA.sub.0 and an aperture 2A.sub.0, and in which ratios A.sub.0 /W.perp. and A.sub.0 /W.parallel. of the apertures to diameters 2W.perp. and 2W.parallel., on the planes normal and parallel to the active layer, of beams which are emitted from the semiconductor laser, pass through the collimator lens and the anamorphic optical element and are incident to the objective lens have the following relations with predetermined values fi.perp. and fi.parallel.:A.sub.0 /W.perp..ltoreq.fi.perp.A.sub.0 /W.

Abstract: A liquid crystal display apparatus wherein laser beams which are modulated in accordance with modulating signals such as video signals are irradiated on a liquid crystal cell for writing the display image or picture on the cell. In the present invention, the laser beams emitted from two laser beam sources are combined at a polarization beam splitter with an angular offset between the respective optical axes equal to .DELTA..theta., and the picture components corresponding to two scanning lines are simultaneously written into the liquid crystal cell during one scanning period, for increasing the image writing speed.

Abstract: An optical head control signal generator comprising a lens (7) disposed in an optical path of a reading light beam caused by an optical head to be incident upon a recording medium and modulated by the recording medium, first, second, third and fourth photosensitive elements (D.sub.2a, D.sub.1a, D.sub.3a, D.sub.4a) divided as four quarters by perpendicular straight lines and responsive to the reading light beam for producing detected outputs based on an outer peripheral portion of a diffraction pattern formed on an exit pupil surface of the lens (7) by the reading light beam, and a synthesizing circuit (28) for producing a first sum output by adding the detected outputs from the first and third photosensitive elements (D.sub.2a, D.sub.3a) and a second sum output by adding the detected outputs from the second and fourth photosensitive elements (D.sub.1a, D.sub.

Abstract: A reflection-type optical recording medium which has a surface on which track guide grooves are formed and in which a layer of a recording material that has an increased energy reflection coefficient in a write portion. The track guide grooves are formed with a depth .phi..sub.0 so that improved efficiency results because of the selection of various parameters of the system.

Abstract: In an optical disc player in which a reading light beam is caused to impinge on an optical disc having a record track formed with an alignment of geometric variations such as a plurality of pits provided in response to information to be modulated in intensity by the record track and a photodetector is provided for detecting the reading light beam coming from the optical disc to generate an output varying in response to the variations in intensity of the detected reading light beam; there are provided a first circuit for producing a reproduced information signal having level variations representing the geometric variations and a tracking error signal which may have level variations depending on the size of each segment of the geometric variations on the strength of the output of the photodetector, a second circuit for detecting the duration of a portion corresponding to each segment of the geometric variations of the reproduced information signal or output of the photodetector and extracting selectively the le

Abstract: A wave plate retarder consists of a stacked plurality of doubly refracting or birefringent high molecular films laminated with a predetermined angle between their respective optical axes to establish a desired phase difference during transmission through the films of components of light polarized along orthogonal axes. The predetermined angle may be selected to provide a phase difference of 1/4 or 1/2 wavelength of light to thus produce a composite wave plate retarder which functions as a 1/4 or 1/2 wavelength plate regardless of the phase difference of components of light produced by transmission through a single film.

Abstract: A mirror is held against a pointed supporting member by a magnetic field of attraction between a first magnetic assembly attached to the mirror and a second magnetic assembly spaced from the first assembly and directly or indirectly attached to the supporting member. The mirror can pivot in two directions in response to magnetic control fields produced by coils around the first magnetic assembly but is prevented by interlocking magnetic fields from rotating on an axis in a third direction. The interlocking fields may be produced by assymmetrically located magnetic members attached to the first and second magnetic assemblies or by dividing both the first and second magnetic assemblies into similar oppositely polarized sectors.

Abstract: In apparatus for optically reproducing information signals from a record carrier, such as a video disc, and in which a light beam from a source, such as a laser is incident through an objective lens onto the surface of the record carrier and a tracking servo control is provided for adjusting the position of the incident light beam on the record carrier; a time base correction mirror operates on the light beams both incident onto, and reflected from the record carrier, and a tracking servo mirror operates only on the light beam incident onto the record carrier. A beam splitter and quarter wave plate are preferably positioned in the optical path between the tracking control mirror and the time base correction mirror. The apparatus may also include a lens with opposed spherical and cylindrical surfaces in the path of the reflected beam between the objective lens and a signal detection photodiode.

Abstract: An apparatus for optically reading or playing-back video or other signal information recorded as pits or other variations in a record track on a reflective record medium surface employs a polarized beam splitter by which a laser light beam is split into first and second polarized light beams which are respectively polarized in different polarization directions. The first polarized light beam is directed in a respective optical path so as to be projected against the record track on the record medium surface and reflected from the latter to a photo-detector or -sensor developing an output representing the recorded signal information, while the second polarized light beam is directed, in an optical path spaced from that of the first polarized light beam, so as to be projected against the record medium surface and reflected from the latter to control a servo-mechanism by which, for example, proper focusing or positioning of the first polarized light beam in respect to the record track is maintained.