Abstract: A housing 25 of a stepping motor 1 consists of a pair of case sections 27 arranged in front and rear in the direction of an axial line L of a rotating shaft 3. The case sections 27 are formed of: an end plate 27a to which a bearing 31 for supporting the rotating shaft 3 is fixed, and a base plate 27b and a top plate 27c extending from the end plate 27a in the direction of axial line L of the rotating shaft 3. The case sections 27 are formed by bending a single plate material.

Abstract: An object of the invention is to suppress an influence of a wavefront aberration which is generated at the time of correcting a third-order spherical aberration, and realize satisfactory information recording and/or reproducing. A collimator lens 4 corrects a third-order spherical aberration which is generated depending on the thickness of a light transmissive layer from a surface of a first optical information recording medium 30, corresponding to an optimal substrate thickness of a first objective lens 6, to an intended information recording surface, assuming that the light transmissive layer thickness of the first optical information recording medium 30 which minimizes a residual third-order spherical aberration at the time of incidence of parallel light into the first objective lens 6 is defined as the optimal substrate thickness of the first objective lens 6.

Abstract: Provides an objective lens, an optical head and an optical disc apparatus (drive) capable of compensating for various types of aberrations including wavelength changes for a plurality of types of optical discs including high density optical discs, DVDs and CDs with a good wavelength dispersion compensation ability and thus capable of providing good recording or reproduction characteristics. The objective lens according to the present invention includes a first lens and a second lens substantially in close contact with each other such that optical axes thereof match each other, and acts as a convex lens as a whole. Each lens includes a central portion including the optical axis and a peripheral portion located in a periphery of the central portion. The central portion of the first lens acts as a convex lens; and the central portion of the second lens acts as a concave lens. Where the refractive index of the first lens at d line (wavelength: 587.

Abstract: A first light source 1a emits a first light flux with a first wavelength. A second light source 1b emits a second light flux with a second wavelength that is different from the first wavelength and a third light flux with a third wavelength that is different from the first wavelength and the second wavelength. A collimator lens 6, a first objective lens 9, and a second objective lens 10 collect the first to third light fluxes as converged light on an optical disc. A first composite photodetector 13 detects the reflected light fluxes from the optical disc. The first composite photodetector 13 includes a first quartered light-receiving unit 13a that receives a light flux obtained by reflection of at least one light flux from among the first to third light fluxes from the optical disc and a second quartered light-receiving unit 13b that receives a light flux obtained by reflection of the remaining light fluxes from the optical disc.

Abstract: An offset-free tracking signal enables stable tracking control even if an optical disc is a multi-layer disc having three or more layers. Light receiving portions of a main region light receiving portion group are arranged between a projection line of a third dividing line on a photodetector and a projection line of a fourth dividing line on the photodetector by stray lights from information layers adjacent to the one, on which a light beam is focused, out of a plurality of information layers. Further, light receiving portions of a subregion light receiving portion group is arranged between a projection line of a first dividing line on a photodetector and a projection line of a second dividing line on the photodetector by the stray lights from the information layers adjacent to the one, on which a light beam is focused, out of the plurality of information layers.

Abstract: Fifth order spherical aberration in addition to third order spherical aberration for an optical information recording medium of which thickness of a light transmission layer changes greatly is corrected. An objective lens collects a laser beam emitted from a semiconductor laser on an optical information recording medium. A spherical aberration correcting portion corrects spherical aberration generated according to a thickness of the light transmission layer of the optical information recording medium, in which the spherical aberration correcting portion includes a collimator lens, a lens holder and a stepping motor for correcting the third order spherical aberration and a liquid crystal element and an applied voltage control portion for correcting the fifth order spherical aberration.

Abstract: An optical disk recording/reproducing device includes a turntable 7 configured to rotate an optical disk 9 and an optical head 3 configured to record/reproduce information in/from the optical disk 9. A stepping motor 13 to drive a collimator lens 16 is mounted on a head base 17 of the optical head 3 and a part of stator 42 of the stepping motor 13 is exposed through an opening 14a of a head cover 14, an opening 15a of a flexible substrate 15, an opening 13a of a cover 41, and an opening 13b of the cover 41.

Abstract: In a process for producing a multilayered information recording medium of the present invention, a process for forming a second signal substrate (110) serving as a resin layer provided between a first thin film layer (102), which is a first information recording layer, and a second thin film layer (108), which is a second information recording layer, includes the steps of: (I) applying a liquid resin (104) onto the first information recording layer; (II) placing, on the resin (104), a signal transfer substrate (105) having a signal surface with a shape of projections and depressions; (III) curing the resin (104) while the signal transfer substrate (105) is placed on the resin (104); and (IV) separating the signal transfer substrate (105) from the resin (104).

Abstract: Provides a coupling lens which, when used in combination with an objective lens for a plurality of types of optical discs such as a high density disc, DVD, CD or the like, is capable of compensating for various types of aberrations including those caused by wavelength changes and thus providing good recording or reproduction characteristics with a good wavelength dispersion compensation ability; and an optical head and an optical disc apparatus (drive). A coupling lens is incorporated into an optical head for collecting laser light emitted from a plurality of light sources and having different wavelengths on an information recording face of different types of optical information recording mediums respectively. The coupling lens comprises a first lens and a second lens which are substantially in close contact with each other such that optical axes thereof match each other and designed such that the laser light having different wavelengths are refracted by the close contact face.

Abstract: When the tilt of an optical disk is detected using a light source of an optical head, the optical head cannot be simplified enough and an optical-disk tilt cannot be detected adequately. The optical head includes: an LED chip; a light-converging element that converges the light which is emitted from the LED chip upon an optical disk; a light-converging element driving means which drives the light-converging element; and a sensor which detects a tilt or a positional shift of the optical disk. In the sensor, the LED chip is placed on a semiconductor substrate which is provided with a plurality of light-receiving chips; the light emitted from the LED chip irradiates the optical disk; the light which is reflected from the optical disk is received by the plurality of light-receiving chips; and based upon the quantity of light which is received at the plurality of light-receiving chips, a tilt or a positional shift of the optical disk is detected.

Abstract: An optical recording medium is provided with a plurality of recording layers, wherein the recording layers are formed such that all the spacings between two recording layers in all the combinations selected from the plurality of recording layers do not coincide with each other. Accordingly, the return of lights reflected by other layers to an optical head along the same optical path as reflected light from a readout layer during the reproduction can be avoided. Therefore, an optical recording medium, from which a good reproduction signal can be obtained, can be provided by suppressing the deterioration of a servo signal and a reproduction signal of a reproducing device due to a variation of interference fringes on a light receiving element.

Abstract: A tilt can be detected highly accurately by minimizing the tilt detection error. An optical head includes: an objective lens for converging a light beam from a light source onto an optical disc; a photodetector section receiving the beam, reflected from the disc, at divided areas on its photodetection plane and outputting light detection signals from those areas; and a tilt detecting section for detecting a relative tilt between the lens and disc based on the detection signals.

Abstract: An object of the invention is to provide an optical element for use in an optical information recording and reproducing device or a like device for recording or reproducing information with respect to an information recording medium using laser light, wherein the optical element is a resin optical element capable of suppressing lowering in transmittance due to deterioration by irradiation of light having a high energy density, and maintaining a high transmittance for a long time. To realize the above object, used is an optical element made of a silicon resin cured material obtained by subjecting a silicon resin composition containing a silsesquioxane compound to a curing treatment.

Abstract: An optical controller includes a light source for emitting light, an object lens for condensing light emitted from the light source, a light detection unit for receiving light reflected on an optical information recording medium and outputting a signal corresponding to the amount of the light, and a laser control unit for controlling the amount of the light emitted from the light source to the information recording surface on which information is to be recorded or reproduced, based on the recording state of an information recording surface disposed closer to the object lens than an information recording surface on which the information is to be recorded or reproduced.

Abstract: To provide an optical head to produce good servo and read signals by reducing the influence of interference by light reflected from a non-read layer of a multilayer optical disc. The head includes: a first optical system for converging light from a light source on a first or second storage layer; a second optical system for receiving and transmitting light reflected from the first layer and stray light reflected from the second layer when the light is converged on the first layer; a photodetector; and a calculator. The photosensitive areas of the photodetector output signals representing intensities of the light incident there through the second system. The reflected and stray light incident on the second system interfere with each other, and the first and second groups of areas are arranged so as to be equally affected by a variation in intensity caused by the interference.

Abstract: An optical head device has at least one upward-reflecting mirror, objective lenses, an objective lens actuator, and a moving mechanism. The upward-reflecting mirror receives an incident luminous flux having a wavelength emitted from a semiconductor, and changes its direction. The objective lenses having mutually different numerical apertures condenses the luminous flux whose direction has been changed by the upward-reflecting mirror to radiate a condensed luminous flux onto an information recording medium. The objective lens actuator moves the objective lenses in the focus direction of the information recording medium so that the luminous flux incident on the information recording medium becomes in a focused state. The moving mechanism moves the upward-reflecting mirror so that the luminous flux is incident on the information recording medium via any one of the objective lenses.

Abstract: A conventional near-field optical head cannot be miniaturized because a scattering body generating a near field and an optical head exist individually. A near-field optical head capable of being significantly miniaturized is constituted by a near-field optical probe slider formed by holding, on a slider, a semiconductor laser, a heat dissipation member, a prism for guiding light from the semiconductor laser to a scattering body and a photodetector element.

Abstract: A drive mechanism according to the present invention includes: a drive body that defines a longitudinal direction; a mover that makes a friction fit with the drive body so as to slide in the longitudinal direction; a base member that supports the drive body so as to allow the drive body to move in the longitudinal direction; a drive element, which is secured to one end of the drive body to vibrate the drive body in the longitudinal direction; and a viscoelastic body, which is arranged between the drive body and the base member in a direction perpendicular to the longitudinal direction.

Abstract: An optical head includes a hologram which extracts, from a luminous flux of reflected light from an optical disk, at least a first luminous flux branch which does not include the optical axis of the luminous flux; and a photodetector which receives the reflected light from the optical disk and produces signal output, wherein the photodetector has light-receiving areas which receive the first luminous flux branch of reflected light from an optical information recording medium layer targeted for recording or playback out of the plurality of optical information recording medium layers of the optical disk, the light-receiving areas are placed in such a way that the signal output resulting from a light spot formed by the first luminous flux branch of the reflected light from the optical information recording medium layer targeted for recording or playback is practically the same between the first and second photodetection areas, and a boundary line of the light-receiving areas is located in such a position as not

Abstract: An aberration correction lens 4 is disposed in a space between a laser light source 3 and an objective lens 5, and a lens holder 10 is frictionally coupled to a drive shaft 7 via a frictional holding body 8. A piezoelectric element 6 is provided to one end of the drive shaft 7. The piezoelectric element 6 extends and contracts in response to an applied voltage. The lens holder 10 is moved relatively with respect to the drive shaft 7 in the drive shaft direction by varying a change rate when the applied voltage to the piezoelectric element 6 is increased and decreased.