873results about "Optical detectors" patented technology

Conventional lenses for DVD/CD compatible writing/reading are liable to CD jitter deterioration due to phase shifts in a central area.

Setting a corresponding base material thickness of an intermediate area of the circumference A2 to greater than 1.2 mm which is the base material thickness of the CD, that is, converging luminous flux that has passed through the intermediate area of the circumference A2 onto a farther place than the information recording surface of the base material thickness of the CD makes it possible to reduce jitter deterioration due to phase shifts. Further, it makes possible to provide a system with higher precision and higher reliability.

An optical information apparatus of the present invention includes: an optical pick-up head including: a light source; a diffraction unit; a condensing unit; a beam splitter; a photodetector; and a tracking error signal generator. An optical recording medium has tracks arranged substantially at a constant pitch. An average of a pitch is tp. When a main beam is placed on the track, a first sub-beam and a second sub-beam are placed between the tracks. The tracking error signal generator performs a differential arithmetic operation with respect to signals output from a light-receiving portion receiving the main beam to generate a first push-pull signal, performs a differential arithmetic operation with respect to signals output from the light-receiving portions receiving the first sub-beam and the second sub-beam to generate a second push-pull signal, and performs a differential arithmetic operation with respect to the first push-pull signal and the second push-pull signal to generate a tracking error signal, in a case where an amplitude of the first push-pull signal obtained at the pitch tp is fluctuated when the light beam is scanned in a direction orthogonal to the tracks of the optical recording medium.

A photodetector used in, for example, an optical pickup device includes: a photodetection unit including a plurality of photodetection elements and provided on a semiconductor chip; a light transmitting unit formed on the upper surface of the photodetection unit; and a light shielding layer having an optical aperture and disposed on the upper surface of the light transmitting unit, with these components being formed integrally. The light transmitting unit is configured such that the distance between the optical aperture and the photodetection unit is maintained constant, and the optical aperture is formed such that the inner portion of an incident light beam passes therethrough. The positioning of the photodetector and the positioning of the optical aperture such as a pinhole or a slit for adjusting the light beam entering the photodetection elements of the photodetector can be made at the same time.

An optical data-storage hard disk drive that uses stationary Phase-Change Microhead Array Chips in place of conventional flying-heads, rotary voice-coil actuators, or other similar types of servo-tracking mechanisms to simultaneously record and/or reproduce data to and/or from a multitude of data-tracks located across the data-surfaces of a multitude of phase-change based disc media using a multitude of microheads.

An optical pickup apparatus includes a first light source to emit a first light beam having a predetermined wavelength, a first optical path changer to change a proceeding path of the first light beam, an objective lens to focus the first light beam on a recording medium, a diffraction member to divide the first light beam reflected by the recording medium into five light regions, the diffraction member having a first diffraction region having a wide width in a direction corresponding to a tangential direction of the recording medium and second through fifth diffraction regions sequentially arranged around the outside of the first diffraction region in a direction corresponding to a radial direction of the recording medium, and a first photodetector having first through fifth light receiving portions to receive the first light beam reflected by the recording medium.

A deformable mirror according to the invention comprises a substrate, a reflector which is supported by said substrate and the shape of whose reflecting areas is variable, and a plurality of drive units for independently driving a plurality of regions of the reflector and thereby controlling the distances between said plurality of regions and said substrate. Each of the plurality of drive units comprises a plurality of electrodes disposed over said substrate, a tilt member which is rotated round the axis of tilt by being attracted by the selected one of the plurality of electrodes, and an action member for varying the distance between a specific region of the reflector and said substrate following the motion of the tilt member.

An optical pickup including an optical member which inhibits interference light reflected from an adjacent layer from being received by a photodetector when an optical information storage medium includes a plurality of recording layers on at least one side thereof. The optical pickup suppresses a photodetector, especially first and second sub-photodetectors of the photodetector, from receiving the interference light reflected from the adjacent layer.

An optical pickup which, when a first light reflected by a recording medium is divided into a central light area and first and second peripheral light areas at both sides of the central light area, divides the first light reflected by the recording medium into at least 6 light areas, and the at least 6 light areas are independently detected from first through sixth light-receiving portions of a photodetector. Hence, the photodetector can detect a tracking error signal whose offset generation due to a shift of an objective lens is insensitive and whose offset generation due to an initial photodetector balance deviation is depressed.

An optical pickup apparatus having an irradiation optical system for condensing a light beam on a track of a recording plane and a photodetection optical system for guiding return light to a photodetector to detect a focal error includes a holographic lens provided in the optical path of the return light for outputting 0-th and ±1st order diffracted lights based on the return light; an optical element provided in front of or behind the holographic lens for providing astigmatism; photodetectors for receiving the 0-th and ±1st order diffracted lights; and servo-signal generating operation circuits connected to the photodetectors for generating a first and second focus error signals having a first and second capture ranges based on the output signal of the photodetector.

A storage medium carries symbols representing digital information encoded in two dimensions. A method and apparatus recovers the symbols using oversampling in two dimensions and derives the information represented by the symbols. In one embodiment, the symbols are carried on motion picture film between the sprocket holes.

An information reading apparatus can detect the coupling state of the input light to a waveguide of a laminated recording medium in a simple manner, so as to enable to focus the input light on a target recording layer to access the information recorded in the target recording layer quickly. The apparatus is compact and is economical to produce. The apparatus has a light source for injecting a light on an input edge of a lamination recording section, assembled into the recording medium containing a lamination of recording layers. Each recording layer has data represented by scattering centers which diffract an input light generated by a converging lens. An input light directing device directs the light source and the converging lens as a unit to focus the input light on a desired location. An image recording device records an informational image generated by guided waves produced within a laminated waveguide. An optical power detector detects output light emitted from an output edge of a specific recording layer as well as scattered light generated from recording layers other than the specific recording layer. An optical power discrimination circuit determines whether an optical power detected by the optical power detector is associated with the output light or the scattered light. Data recorded in any specific recording layer can be accessed quickly and simply by focusing input light on a core layer of a multi-layered hologram recording data storage medium. Because the absolute positional information stored in the storage medium is minimized, data storage capacity of the storage medium is almost unaffected while making the apparatus compact and low cost.

The object of the invention is to provide a light receiving amplification element applicable to an optical pickup apparatus comprising a semiconductor two-wavelength laser element and one condensing lens. The light receiving amplification element is provided with a plurality of light receiving portions corresponding to different wavelengths, a plurality of trans-impedance type amplifiers connected to the light receiving portions according to the different wavelengths and adaptable to the different wavelengths and switching portion for switching output from the trans-impedance type amplifier according to each of the wavelengths.

A tilt servo control device of an apparatus for recording information on and reproducing information from an optical recording medium, the apparatus comprising an optical system for leading a laser beam emitted from a light source to a recording surface of the optical recording medium and a laser beam reflected by the recording surface of the recording medium to a split type photo detector and a read signal generator for generating a read signal in accordance with an output signal of the photo detector. The tilt servo control device generates a push-pull component signal including a differential component of output signals of respective split portions of the photo detector, generates a tilt error signal representing a tilt angle at a position of the laser beam irradiating the recording surface and an optical axis of the laser beam based on the push-pull component signal, and drives a tilt angle adjuster for adjusting the tilt angle so as to reduce the tilt error signal.

In an optical pickup, the focal position of the reflected light from the information bearing surface where information is to be reproduced and that of the reflected light from other information bearing surfaces are adjusted by an optical device such that the two reflected light components are separated optically.

The present invention aims to generate an offset-free tracking signal and to realize a 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 is 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.

An optical pickup can be provided, the optical pickup being capable of recording and playback of a plurality of optical disks having different specs by using light beams of different wavelengths, and further being suitable for integrating the semiconductor lasers and light receiving elements into a single package, by including: first and second semiconductor lasers adjacently disposed; a three-beam diffraction grating for generating three beams for tracking control; a second hologram element for diffracting light of the second semiconductor laser to guide it to a photosensor; a complex polarization beam splitter (PBS) for reflecting only light from the first semiconductor laser; and a first hologram element for diffracting light of the first semiconductor laser to guide it to the photosensor.

An optical disc apparatus and a wobble signal detection method in which a light beam projected onto an optical disc and reflected by the optical disc is divided into at least four light regions in the direction corresponding to the radial direction of the optical disc to detect the light regions, and a wobble signal is detected by performing a subtraction on first and second difference signals, the first difference signal obtained by performing a subtraction on detection signals for the inner light regions of the divided and/or detected light beam and the second difference signal obtained by performing a subtraction on detection signals for the outer light regions of the divided and/or detected light beam. Accordingly, when a wobble signal is reproduced from an optical disc manufactured by a wobble modulation manner, a wobble signal is prevented from being degraded due to the interference (cross talk) from the wobbles of adjacent tracks, even though the track pitch of the optical disc is reduced to improve the recording density.

An optical pickup apparatus for performing recording, reproduction and deletion of information onto each of three types of optical recording mediums including light sources of a blue wavelength zone, light sources of a red wavelength zone and light sources of an infrared wavelength zone. The optical pickup apparatus also has a single object lens which condenses a light from any of the light sources and a single aberration correction device disposed in a common light path between each of the light sources and the object lens.

A compatible optical pickup compatibly using a high density recording medium and at least one low density recording medium, includes an objective lens to form a light spot suitable for use on a recording surface of the high density recording medium by focusing a corresponding incident light beam with a high NA suitable for the high density recording medium and a light spot suitable for use on another recording surface of the low density recording medium by focusing another corresponding incident light beam, and an actuator provided to apply tilt to the objective lens. The light beam for the low density recording medium is incident on the objective lens as a divergent beam. When the objective lens is shifted in a radial direction, a tilt is applied to the objective lens corresponding to the shift.

An optical disc apparatus is provided, which comprises a lens tilting section for tilting an objective lens to correct coma aberration occurring in a light beam spot focused on an information surface of an optical disc, a spherical aberration correcting section for correcting spherical aberration occurring in a light beam spot focused on the information surface, and a lens tilt-spherical aberration correction control section for controlling the spherical aberration correcting section to change an amount of spherical aberration correction performed by the spherical aberration correcting section depending on a tilt of the objective lens tilted by the lens tilting section.