Abstract: In an image exposing apparatus and an image exposing method, a deterioration of an image quality caused by stray light is suppressed, while both a sensitive level and a non-sensitive level are properly set in accordance with a type of photosensitive material. In the image exposing apparatus, a recording level setting unit calculates a recording level corresponding to a light amount level stored in a recording level light amount memory and sets the calculated recording level. A non-recording level setting unit calculates a non-recording level from an extinction ratio, which corresponds to a type of photosensitive material stored in a photosensitive material information memory, and the recording level. An output voltage setting unit sets an output voltage such that a detected voltage becomes equal to one of the recording level and the non-recording level.

Abstract: When a ratio R between a total angle &phgr; of a widening angle in a median intensity of light of a light source (a GaN based semiconductor laser) and a total angle 2/&phgr; of a widening angle of light defining a numerical aperture NA of a collimator optical system (collimator lens) is defined as R=(sin−1NA)×2/&phgr;, the numerical aperture of the collimator optical system (collimator lens) is set so that 2.0≧R≧0.58. Thus, an image exposure device is provided that can suppress stray light of a light source that emits a large amount of stray light.

Abstract: A semiconductor laser pumped solid state laser includes a solid laser medium, a semiconductor laser which radiates a pumping laser beam for pumping the solid laser medium, and a light entrance optical system which converges the pumping laser beam in the solid laser medium. The semiconductor laser is disposed with its beam radiating axis inclined to the optical axis of the light entrance optical system so that the pumping laser beam travelling from the semiconductor laser to the solid laser medium and a laser beam reflected at the pumping light inlet side end face of the solid laser medium travel different optical paths. A light-shielding plate which intercepts the laser beam reflected at the pumping light inlet side end face of the solid laser medium is provided between the semiconductor laser and the solid laser medium.

Abstract: An optical element consists of an LN or LT crystal doped with MgO or ZnO. A +z surface and a -z surface of the crystal are connected to each other by means of a metal jig and an indium sheet. The +z surface and the -z surface may also be connected to each other by means of an electrically conductive wire material. The optical element may be a bulk crystal, an optical waveguide type electro-optical modulator, or a bifurcated interference type optical modulator. In this way, an optical damage resistant property of the optical element is improved.

Abstract: A light beam recording device. A light beam irradiated from a light beam irradiating device is scanned onto an object to be illuminated, which is provided in a vicinity of a focal position, while being focused by a scanning optical system. A converging member is disposed on an optical path between the light beam irradiating device and the scanning optical system, and converges a light beam which is incident on the converging member. An optical path changing device is disposed in a vicinity of a converging position of a light beam which is converged by the converging member, and changes an optical path of the light beam.

Abstract: An opto-magnetic pick-up device for use in an information recording and reproducing device is disclosed. The device comprises a phase difference correcting device capable of correcting the phase difference between the linearly polarized component of the reflected light from the recording medium and a polarized component vertical to the linearly polarized component.

Abstract: A magneto-optical recording medium comprises a substrate and a magneto-optical recording film overlaid on the substrate. The magneto-optical recording film is composed of a first protective dielectric layer, a recording layer, a second protective dielectric layer, and a reflection metal layer, which layers are overlaid in this order on the substrate. The thickness of the first protective dielectric layer falls within the range of 950 .ANG. to 1,300 .ANG.. The thickness of the recording layer falls within the range of 200 .ANG. to 400 .ANG.. The thickness of the second protective dielectric layer falls within the range of 100 .ANG. to 600 .ANG.. The thickness of the reflection metal layer falls within the range of 200 .ANG. to 800 .ANG..

Abstract: In an optical information recording and reproducing apparatus for recording and reproducing information by controlling the focus of an optical system for condensing and projecting lights of a light source onto a recording medium, an offset part produced in case the lights are condensed and projected in a focus servo state in data writing regions in the recording medium and prepit regions which are adjacent to the data writing regions and in which discriminating codes are written is detected in the respective format regions by a format detecting means and an offset fluctuation controlling voltage is impressed on the basis of this detecting signal to inhibit the fluctuation of the offset in the respective regions of different formats.

Abstract: In a method of detecting track crossings on an optical disc, a light source irradiates a light beam onto an optical disc having guide tracks in the form of a recess and the light beam is reflected and diffracted into a zero order light beam and positive and negative primary light beams. The light beams are defocused so as to produce interference patterns between the zero light beam and the positive and negative primary light beams. The interference patterns are detected by a four split light detector disposed between two parts of a two split detector. The outputs of the detectors are fed to an adder and to a subtractor for producing a sum signal and a difference signal respectively. The sum signal and difference signal are fed to a phase detector. Defocusing of the light beams is effected by a focusing coil to which is fed the amplified output of an adder of a reference signal controlled by a control circuit.

Abstract: A linearly polarized light is projected upon a recording medium of a photomagnetic type; the reflected light is rotated by an appropriate angle through a halfwave plate and split into a reflected light and a transmitted light through a beam splitter having reflection factors of 0 or 100% for p- or s-polarized light in such a way that the beam splitter functions as an analyzer for one of the reflected and transmitted lights. The other of the reflected and transmitted lights is passed through an analyzer. The two lights passed through the beam splitter and the analyzer are detected by two photodetectors separately and applied to a differential amplifier to generate a reproduction signal of high S/N ratio without the use of a half mirror R.sub.p =R.sub.s =50% which is very difficult to manufacture.

Abstract: An optical disk apparatus has an optical head. The optical head emits a light beam onto an optical disk and forms pits in the optical disk, thereby recording a signal. A detector detects the relative inclination between the optical head and the optical disk and generates a signal corresponding to this relative inclination. A beam intensity correction circuit corrects the intensity of the light beam in accordance with the relative inclination to form proper pits. In one embodiment, the intensity of the light beam is increased when the relative inclination is increased.

Abstract: An optical memory device comprises a modulator for modulating a laser beam in accordance with recording data, an objective lens for focusing the output laser beam from the modulator on a recording medium, a photosensor arranged at the conjugate position with the focal point of the objective lens, and a judging circuit for detecting erroneous writing in accordance with an output from the photosensor and a source of the recording data. The photosensor is divided into first and second segments by a line which is perpendicular to a direction corresponding to relative movement of the focused light beam on the recording medium. The difference signal between the outputs from the first and second segments is supplied to the judging circuit.

Abstract: An optical recording/reproducing apparatus has a beam emitting device adapted to emit at least two light beams in directions at a minute angle to each other. The light beams are condensed by a condensing member onto slightly separated two points on a disk and reflected by the disk. The light beams from the disk are polarized to a prism by a polarizing device. The prism refracts the light beams from the polarizing device, thereby increasing the relative angle between the light beams. The refracted light beams are converged by a converging lens on a detector.

Abstract: An optical recording and reproducing apparatus includes a first semiconductor laser for emitting a recording laser beam whose intensity is modulated in accordance with an information signal to be recorded and a second semiconductor laser for emitting a reproducing laser beam having a constant intensity. The recording and reproducing semiconductor lasers are commonly mounted in a supporting member which is mounted on a pick-up plate arranged movably in a radial direction of a rotating optical disc. The recording and reproducing laser beams are composed with each other by means of a substantially parallelogram shaped prism having a reflection surface for reflecting the reproducing laser beam and an optical surface upon which the reproducing laser beam is made incident at an incident angle larger than a critical angle and the recording laser beam is made incident at an incident angle near Brewster's angle.

Abstract: An optical memory device comprises a modulator for modulating a laser beam in accordance with recording data, an objective lens for focusing the output light beam from the modulator on a recording medium, a sensor arranged in the far field of the objective lens, and a judging circuit for detecting an erroneous writing operation in accordance with an output from the sensor and the recording data. The sensor has a square detecting surface divided into four segments by lines which form angles of .+-.45.degree. with respect to the direction of relative movement between the recording medium and the focused light beam. The difference between the sums of outputs from two pairs of opposing segments is supplied to the judging circuit.

Abstract: In an optical system for synthesizing a plurality of light beams, a first light beam of parallel light rays emitted from a laser beam source is incident on an inclined face of a right angle prism through the prism. A second light beam of parallel light rays emitted from a laser beam source is incident to the inclined face at a predetermined angle of incidence. The first light beam is emitted to the inclined face at an angle of incidence equal to a critical angle so that the first light beam is totally inflected by the inclined face and transmitted in a predetermined direction. The second light beam is refracted at an angle of refraction substantially equal to the Brewster's angle, and then transmitted in a direction which defines a predetermined angular difference with the predetermined direction of the first light beam. A multi-layered film is formed on the inclined face.

Abstract: A method and an apparatus for detecting a focussing error signal and a tracking error signal of an objective lens with respect to an information track of a video disc on which a reading light spot is focussed by the objective lens includes a detection prism having a reflection surface which is set substantially at a critical angle and a light detector for receiving the light flux reflected by the reflection surface. The light detector is arranged in a far field of the track and having four light receiving regions divided along two orthogonal directions. The focussing error signal is derived as a difference between output signals from the regions aligned in a track direction and the tracking error signal is derived as a difference between output signals from the regions aligned in a direction perpendicular to the track direction. An information signal is obtained as a sum of the output signals from the four regions.

Abstract: An input signal containing a base line which fluctuates to a great extent is detected or restored by comparing the input signal with reference levels which are shifted in accordance with the fluctuation of base line. The input signal is sampled at a variable sampling rate and an average of sampled values for a predetermined period is derived to produce a profile signal which resembles accurately the fluctuation of the base line. The profile signal thus obtained is added to upper and lower threshold voltages to produce the reference levels which have been corrected in accordance with the fluctuation of the base line of input signal.

Abstract: A method of separating at least two light beams propagating in the substantially same direction but which propagate with making a small angle therebetween is disclosed, which comprises making one of said light beams incident upon an interface between an isotropic first optical medium having a first refractive index and an isotropic second optical medium having a second refractive index lower than said first refractive index at an incident angle substantially equal to the Brewster angle so that the light beam is substantially totally transmitted through said interface; and making the other light beam incident upon said interface at an incident angle greater than the critical angle so that the light beam is totally reflected by said interface.

Abstract: A disc-shaped record medium has a recording surface which is divided into a number of concentric recording regions and has a number of concentric guide tracks formed at boundaries between successive recording regions. A number of concentric or spiral information tracks are formed in an optically readable form in respective recording regions with a constant pitch in reference to respective guide tracks and the guide tracks are also recorded in an optically readable form. In an instance of effecting the recording or reproducing for a certain recording region, the guide track related to the relevant recording region is always read out by a tracking light beam which is controlled to trace the guide track and a recording or reproducing light beam is controlled with reference to the guide track so as to trace the information track precisely.