Abstract: The present invention provides for a optical head device having a beam-guiding optical device to bring beams of different wavelengths which are emitted by separate light sources together onto the same optical axis or to guide the beams onto a common photo receiving device. The beam-guiding optical device includes an incident plane and an exit plane and the incident plane and the exit plane are back to back. One of the incident plane and the exit plane has a stair-like surface wherein a step height between neighboring treads in the stair-like surface is set to cause a phase difference of n wavelength to one of the beams passing through the neighboring treads and n is equal to 1, 2, 3 . . . .

Abstract: A flame retardant polyamide resin composition having excellent mechanical strength and tracking resistance. The flame retardant polyamide resin composition comprises (A) 100 parts by weight of polyamide resin, (B) from 1 to 20 parts by weight of melamine cyanurate and (C) from 5 to 120 parts by weight of a whisker comprising a metal borate.

Abstract: In an optical pickup device, a first light source and a second light source, light emission points of which are not on an identical optical axis, are provided. A first laser light beam and a second laser light beam, wavelengths of which are different from each other, are respectively emitted from the first and second light sources. The first and second laser light-beams reflected from an optical recording medium are diffracted based on different diffraction order, such that the diffracted first and second laser light beams are received by a common light receiving element.

Abstract: The object is to provide a flame retardant polyamide resin composition having excellent tensile elongation at break and excellent properties for use as a hinge. A flame retardant polyamide resin composition is provided, which comprises 100 parts by weight of a polyamide resin mixture consisting of a first aliphatic polyamide and at least one polyamide selected from the group consisting of a second aliphatic polyamide, which differs from the first aliphatic polyamide, and a semi-aromatic polyamide, and from 0.4 to 20 parts by weight of a melamine cyanurate-type flame retarder.

Abstract: A semiconductor laser apparatus comprises a semiconductor substrate, a semiconductor laser which is fixed on the semiconductor substrate and a prism having a slanted plane. The prism is placed such that its slanted plane faces a side across from the semiconductor laser. The apparatus also includes an optical detector for monitoring which is formed on the surface of the semiconductor substrate. The surface is covered by the prism. The following are formed on the slanted plane of the prism: a reflection region on which the surface is processed for reflecting a part of an emitted light beam from the semiconductor laser and a transmissive refraction region on which the surface is processed such that the remaining part of the emitted light beam is transmitted and refracted to be guided to a light receiving plane of the optical detector for monitoring.

Abstract: In accordance with the invention, an optical head assembly comprises a laser light source, an objective lens for converging light emitted from the laser light source onto an recording surface of an optical recording medium, an optical detector device for detecting the light reflected upon the recording surface, a modulating diffraction grating for splitting the light emitted from the laser light source into 0th-order beam, +1st-order beam and -1st-order beam in a track direction of the recording surface, emitting the three beams toward the center of the track of the recording surface, and causing, with respect to the +1st-order beam and -1st-order beam, astigmatisms of different focal points in a direction orthogonal to the track direction, and a light-guiding device for guiding three returning beams reflected from the recording surface to the optical detector device.

Abstract: An optical head assembly comprises a laser light source, an objective lens for converging a laser light emitted from the laser light source on an optical recording medium, an optical detector for detecting a returning light from the optical recording medium, a diffraction unit mounted in an optical path between the laser light source and objective lens for positioning multiple diffraction grating means, a base of the optical head assembly for supporting the objective lens, the laser light source and the optical detector, and a diffraction grating unit retaining portion formed on the base for holding the diffraction grating unit.

Abstract: An optical head assembly comprises a laser light source, an objective lens for converging laser light rays emitted from the laser light source at an optical recording medium, a hologram element placed in the optical path between the laser light source and the objective lens, an optical detector for signaling that detects returning light rays from the optical recording medium and an optical detector for monitoring that detects a portion of the laser beams emitted from the laser source toward the optical recording medium. The hologram element has first and second diffraction areas; the first diffraction area diffracting the returning light rays to guide them to the optical detector for signaling; the second diffraction area reflecting and diffracting a portion of the light rays emitted from the laser light source at a fringe-like reflecting portion to guide them to the optical detector for monitoring.

Abstract: An optical pickup head apparatus for reading information signals from a recording medium having a laser beam light source, an objective lens and a photodetector, the improvement comprises a holographic optical element constructed of a pair of diffraction gratings having different diffractive conditions wherein the element is split into two by a split line near its optical axis as a border and a diffraction generation prevention device for preventing the generation of unwanted diffracted beams from a recording medium. The optical pickup head apparatus irradiates a laser beam emitted from the light source onto a recording medium via the holographic optical element and the objective lens. Beams reflected from the recording medium are guided to the photodetector via the objective lens and the holographic optical element.

Abstract: An optical pickup head apparatus for reading information signals from a recording medium having a laser beam light source, an objective lens and a photodetector, the improvement comprises a holographic optical element constructed of a pair of diffraction gratings having different diffractive conditions wherein the element is split into two by a split line near its optical axis as a border and a diffraction generation prevention device for preventing the generation of unwanted diffracted beams from a recording medium. The optical pickup head apparatus irradiates a laser beam emitted from the light source onto a recording medium via the holographic optical element and the objective lens. Beams reflected from the recording medium are guided to the photodetector via the objective lens and the holographic optical element.

Abstract: A polarizing beam-splitter comprises an optically isotropics crystalline substrate and a birefringent material layer made of an oriented polydiacetylene film formed on the optically isotropic crystalline substrate. A periodic grating photo-mask is formed in the birefringent material layer by an area that is changed into a different color phase when an ultra violet light is irradiated in a predetermined pattern on the birefringent material layer and by an area in which the color remains unchanged. The periodic grating photo-mask has a diffraction efficiency for the orientation of the oriented polydiacetylene film in the area that is changed into a different color phase which is lower than that in the area in which the color is unchanged.

Abstract: An optical pickup device includes a light source irradiating a record medium with plural light spots of light emitted therefrom, a plurality of light detecting elelments to which reflected light of the light spots are guided, respectively, to adequately synthesize and compare outputs of said light detecting elements, thereby reading information recorded in tracks of the record medium, and detecting an tracking error and a focusing error, and a hologram element which splits light emitted from the light source into plural beams is disposed in an optical path between the light source and the record medium, said hologram element is split by a split line, said split line elongating in a direction perpendicular to a track of the medium on an optical axis, and a hologram pattern having a diffraction function which is substantially directed in the track direction is disposed on at least one side of said split line, thereby differentiating diffraction conditions on both sides of said split line from each other.

Abstract: A polarizing beam splitter includes: an optically isotropic substrate; a layer of birefringent material formed on top of said optically isotropic substrate; and a periodic pattern of ridges and grooves formed on a surface of said optically isotropic substrate to make a grating; and a refractive index equal to either the refractive index of the birefringent material for ordinary light or the index for extraordinary light, said grooves being filled with the material.

Abstract: A displacement detecting device for optical head is disclosed which is capable of stably generating displacement detecting signals without being affected by fluctuation of wavelength of light emitted from a light source. The displacement detecting device is provided for use in an optical head which comprises a optical sensor for reading information recorded on an optical information recording medium by irradiating the optical information recording medium with light from a light source and detecting reflected light from the irradiated surface of the recording medium as well as detecting focus displacement and track displacement by utilizing diffracted light of the reflected light. The optical sensor is provided with wavelength fluctuation component detector for detecting wavelength fluctuation components in the reflected light.

Abstract: A tracking error signal and a focus error signal can be obtained with those components of the light (plus and minus first-order light) which have been diffracted by a hologram device whereas the undiffracted zero-order light component is for the sole purpose of producing RF signals. As a result, RF signals can be detected without using a segmented photodetector while insuring that output signals of a constant intensity are produced even if there are changes in the spot diameter and position. In addition, any aberrations that are caused by an half-mirror are corrected by optics that is provided in the optical path connecting the half-mirror and the light-receiving elements of a photodetector and this insures that even if an objective lens moves, detection spots on the individual light-receiving elements will move on the latter without causing any offset errors.

Abstract: In an optical pickup system, the light emitted from a source to illuminate an optical recording medium is reflected and directed via a beam splitter to a photodetector so as to read information signals, and a hologram device for splitting the emerging light from the source into a plurality of beams is provided as an integral part of the entrance surface of the beam splitter.

Abstract: This invention pertains to a displacement detecting device for an optical head for detecting focal point displacement of irradiation light. The displacement detecting device has optical means for converting reflected rays from an irradiated face into an astigmatic bundle of rays and a photodetector for detecting a change in the the focused shape. The displacement detecting device thus detects focal point displacement of irradiation light. The optical means is obtained by integrally forming a plurality of Fresnel zone plates having rectilinear gratings, focusing reflected rays from the irradiated face, and having different focal lengths.

Abstract: A tapered optical waveguide is disclosed, which comprises a substrate having a plane surface for forming a waveguide layer, whose refractive index is higher than that of the substrate, which substrate is transparent with respect to guided light, and a waveguide layer formed on the plane surface of the substrate, in which light taken out on the substrate side is focused so as to form a small spot at a position distant from the interface between the waveguide layer and the substrate.

Abstract: Even though a female member is sewed on a suit material of clothes with any surface thereof directing upward, a function proper to the female member can be exhibited by the female member comprising a central ring-shaped portion provided with a through hole with which a projecting portion of a male member is detachably engageable, four projecting pieces radially projecting outward from said central ring-shaped portion and an outside ring-shaped portion for connecting said projecting pieces to each other at a pointed end thereof integrally formed of resinous material, adapting to sew said projecting piece on a suit material of clothes, forming a radial slit communicating with said through hole in said central ring-shaped portion and each of said projecting pieces, and symmetrically forming the face and the back thereof as a whole.

Abstract: The invention provides an improved plastic socket component of the female snap of a snap fastener, which socket component is attached to one face of a flexible sheet such as the cloth of a garment by means of a rivent driven in from the other face of the flexible sheet and includes a cavity for coupling and uncoupling with a projection formed on a male snap. The cavity is surrounded by a thick peripheral wall having a plurality of relatively long arcuate embossments arranged at small intervals in the peripheral direction on an upper inner surface portion of the wall and a plurality of arcuate slits substantially equal in length to the embossments and arranged outwardly opposite thereto, the slits extending vertically through the peripheral wall. Adjacent pairs of the slits are interposed by thick wall portions having high rigidity.