Abstract: The invention relates to an information carrier comprising a layer (L) for storing data, said layer forming a light-guide having an internal face (IF) having placed thereon a matrix of indentations (ID1, ID2), said indentations (ID1) being shaped so as to deviate part of an input light beam (ILB) applied to said layer towards a first edge (E1) of said information carrier along a first direction (d1), the presence of an indentation reflecting a stored data having a first state, the absence of an indentation reflecting a stored data having a second state. The invention also relates to a reading system for reading this information carrier.

Abstract: An optical head includes a blue color laser beam sources, a red color laser beam sources, a dichroic prism, a collimator lens, a beam splitter, an objective lens, a photo detector element, a detection lens, and a hologram element having a first hologram and a second hologram and the first hologram changes a phase of a +1st order diffraction light of a blue color laser beam so that its condensing point falls on a second photo detecting portion and the second hologram changes a phase of a ?1st order diffraction light of a red color laser beam so that its condensing point falls on a third photo detecting portion.

Abstract: The present invention provides a photodetector capable of generating highly accurate tracking and focusing error signals free of variations in light quantity caused by interference, in an optical pickup with a two-wavelength multilaser. The photodetector comprises first three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a first wavelength and second three light receiving areas arranged linearly to receive three light beams respectively resulting from splitting of a light beam emitted from a laser light source of a second wavelength longer than the first wavelength. The distance between both-end light receiving areas out of the first three light receiving areas is longer than the distance between both-end light receiving areas out of the second three light receiving areas.

Abstract: An optical pickup includes a detector, a plurality of light guiding units, and a switching controller. The detector detects, using a plurality of detection areas, a reflected light beam that is emitted from a predetermined light source and is reflected off an optical recording medium. Each of the light guiding units has a specific light guide pattern and inputs a predetermined part of the reflected light beam to a predetermined detection area in accordance with the light guide pattern. The switching controller switches and selects the light guiding unit that acts on the reflected light beam from among the plurality of light guiding units according to a predetermined switching condition.

Abstract: A method for designing an optical pickup is provided. The optical pick includes a monolithic laser diode that emits a laser light beam for DVD recording and a laser light beam for CD playback, two photodetective portions, and an objective lens, for each of the emitting portions of the monolithic laser diode for emitting the DVD recording and CD playback laser light beams respectively, the specification of the error of the emission direction thereof is determined according to the following formula: |(???1×??1×Dpd1/Dob1????2×??2×Dpd2/Dob2)×Kpd2|??, where, “1” corresponds to the DVD recording laser light beam and “2” corresponds to the CD playback laser light beam, ??? represents the emission angle; ?? represents the sensitivity; Dob represents the diameter of the light beam; Dpd represents the diameter of the spot formed by the light beam; Kpd represents the sensitivity; and ? represents the tolerable value.

Abstract: A polarizing beam splitter for separating an upstream beam from a downstream beam according to the polarization of an incident beam is provided between first and second light sources emitting laser beams at respective wavelength and an objective lens. A phase plate for providing a phase difference to a beam incident on the polarizing beam splitter is provided between the polarizing beam splitter and the light sources. A portion of the laser beam incident on the polarizing beam splitter is reflected by the polarizing beam splitter and caused to be incident on a photo-detecting unit, so as to prevent an unnecessary portion of the laser beam is incident on the photo-detecting unit. According to the invention, the laser beam is used efficiently and the cost of fabricating an optical disk apparatus is reduced by eliminating a need for a gain controlling circuit in the photo-detecting unit.

Abstract: The invention relates to a diffraction grating, a light-receiving element, and an optical head and an optical recording/reproducing apparatus utilizing them and provides a diffraction grating and a light-receiving element capable of detecting a signal of high quality and an optical head and an optical recording/reproducing apparatus utilizing them. A diffraction grating includes a diffracting region which is formed only on a light exit surface and which diffracts and separates first laser light or second laser light emitted by a two-wavelength semiconductor laser to generate a main beam and positive and negative first order sub beams. The depth of concavity formed on the diffracting region is 220 nm. The irregularities are formed such that the pitch length thereof is 22 ?m and such that a convexity thereof has a width of 17.6 ?m. The ratio of the width of the convexity to the pitch length of the irregularities is 0.8.

Abstract: An optical pickup apparatus comprises a photo detector that receives light reflected from a medium; and a housing that is mounted with the photo detector. The photo detector is fixed to the housing with the use of an adhesive to mount the photo detector on the housing. The housing is provided with a displacement preventer that prevents displacement of the photo detector or the adhesive relative to the housing. The displacement preventer has fixing portions that extend along a plurality of directions. The photo detector is mounted on the housing by applying the adhesive to the displacement preventer.

Abstract: An optical head device may include a frame type of laser beam emitting element provided with a heat radiating fin on which a laser chip is mounted, a device frame on which the laser beam emitting element, a light receiving element and an optical system are mounted, and a heat radiation member formed of material having a superior heat conduction property. The upper face of the laser beam emitting element is fixed to the device frame, and an under face of the heat radiating fin which corresponds to a portion where the laser chip is mounted is exposed on an outer side to form an exposed part, and the heat radiation member is disposed to extend over the exposed part and the device frame.

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: A light detecting apparatus includes a first photodetector for receiving 0th reflected light from a first information surface, a second photodetector proximate to the first photodetector for receiving the reflected light of a positive higher-order diffracted light from the first information surface, and a third photodetector proximate to the first photodetector for receiving the reflected light of a negative higher-order diffracted light from the first information surface. Light-receiving areas of the second and the third photodetectors include other-order light receiving areas that receive reflected light of the 0th order light from a second information surface where the 0th order light is not be focused, and wherein portions of the other-order light receiving areas of the second and the third photodetectors include light reception prohibited areas that prohibit the reception of the reflected light of the 0th order light from the second information surface.

Abstract: A front photo detector (FPD) of an optical pick-up for an optical recording and playing apparatus having no gain selection switch, a simplified configuration, an improved prevention of an abnormal operation due to an error in gain selection, and improved reliability. The front photo detector includes a photo diode unit, a current-voltage amplifying circuit, and a voltage amplifying unit. The photo diode unit outputs current proportional to the power of the light emitted from one of a plurality of laser diodes. The current-voltage amplifying circuit converts the current output from the photo diode unit into a voltage. The voltage amplifying circuit amplifies the voltage output from the current-voltage amplifying circuit by a predetermined gain.

Abstract: Provided is a photoelectric converting device including: first photoreceptors each converting a received main beam to a current; second photoreceptors each converting a received first sub-beam to a current; and third photoreceptors each converting a received second sub-beam to a current; first current-voltage converting circuits each converting the current converted by a corresponding one of the first photoreceptors to a voltage; current amplifying circuits each amplifying or attenuating the current converted by a corresponding one of the second photoreceptors; switching circuits each supplying one of the current amplified or attenuated by a corresponding one of the current amplifying circuits and the current converted by the corresponding one of the second photoreceptors; and second current-voltage converting circuits each converting a sum of the current supplied by a corresponding one of the switching circuits and the current converted by a corresponding one of the third photoreceptors to a voltage.

Abstract: The present invention relates to a detector configuration, pickup device and driving device for multi-layer record carriers, wherein main beam detector means and two pairs of side-beam detector means disposed on opposite sides of the main beam detector means are provided for suppressing crosstalk effects. As an example, the two three-spot systems obtained can be used for focus error signals and tracking error signals, respectively, wherein satellite spots can be controlled to have a desired fringe pattern either in-phase or anti-phase with that of the main beam. Besides the reduction of focusing and tracking errors, the above measure allows to reduce spacer layer thickness.

Abstract: A storage media for storage of data thereon is provided. The storage media including: a first layer, the first layer being substantially transparent to a predetermined radiant energy used for reading the data; and a second layer formed on the first layer and being substantially opaque to the radiant energy, the second layer having a pattern comprising a plurality of holes, each of the holes having a largest dimension which is greater than a wavelength of the radiant energy, the data being stored as the presence or absence of a hole in the pattern. Also provided are a method for fabricating the storage media as well as an apparatus and method for reading the data stored on the storage media.

Abstract: An optical pickup unit comprising: a circuit connected to a light emitting device emitting light; and a counterpart circuit connected to the circuit, the circuit being soldered to the counterpart circuit.

Abstract: A light detector includes a light-receiving device that receives a light beam applied from a light source irradiating an optical recording medium with the light beam and that generates detection signals, and a power monitor circuit section that generates a power monitor signal for monitoring output power of the light source in accordance with the detection signals. The device includes split light-receiving elements. The detection signals are output from the split light-receiving elements as split detection signals. The section includes an amplifying circuit generating the power monitor signal and outputting the power monitor signal as differential signals, a fixed resistor determining a gain of the amplifying circuit, and a position-detecting signal output circuit generating position-detecting signals in accordance with the split detection signals. At least the light-receiving device, the amplifying circuit, and the fixed resistor are integrated on an identical semiconductor substrate.

Abstract: A method and an apparatus for driving an optical recording medium for recording and/or reproducing various information for the optical recording medium, in which the output power ratio of the light source may be reduced for recording and reproduction, for optical recording media of different sorts, or for respective recording surfaces of a multilayered optical recording medium, so that optimum characteristics may be realized even with use of an easy-to-fabricate light source or a light source with a smaller light output rating.

Abstract: In an optical disc device, the recording laser light power from a semiconductor laser is adjusted to a desired power. A front monitor PD is provided near the semiconductor laser LD of an optical pickup 16, and the recording layer light power is detected. A system controller 32 stores in memory an approximating equation for a correction coefficient for the recording power based on the detection signal characteristic when the recording laser light is a multi-pulse signal, uses the approximating equation to compute the correction coefficient for the desired recording power, corrects the detected signal level from the front monitor PD, and executes feedback control of the laser power emitted from the LD.

Abstract: In a light receiving amplifier circuit, a dummy amplifier has an identical structure with an IV amplifier except that the dummy amplifier is not connected to a light receiving element and includes a capacitor, i.e., a band limiting capacitor. Further, the capacitor is connected between the collector of the grounded-emitter transistor Tr and GND.

Abstract: The present invention is provided with a detection region for detecting light that is reflected from a first or a second information recording medium and that passes through an optical element. The first information recording medium and the second information recording media are multi-layer disks that have at least two layers, and the detection region includes a detection region (41) for detecting first order and above diffracted light that has a first wavelength, and a detection region (42) for detecting first order and above diffracted light that has a second wavelength.

Abstract: Disclosed are an optical pickup module and a manufacturing method thereof. The manufacturing method of an optical pickup module includes: forming a wet-etching mask layer at an outer portion of an upper surface of a silicon substrate to be used as a sub mount; etching a middle portion of the silicon substrate by using the wet-etching mask layer thereby forming a cavity, forming an inclination surface at the etched portion, and then removing the wet-etching mask layer; forming an insulating layer on an entire upper surface of the to silicon substrate; forming an electrode layer on an upper surface of the insulating layer; forming adhesive layers at a part of an upper surface of the electrode layer; and arranging a light emitting device at an upper surface of one adhesive layer and arranging an MPD at an upper surface of another adhesive layer by a fixation thereby completing an optical pickup module.

Abstract: An optical pick-up device includes a laser diode, an objective lens for focusing a light beam emitted from the laser diode on an optical disc, an optical detector for receiving a reflected beam from the optical disc, a beam splitter for causing the light beam emitted from the laser diode and a reflected beam to pass therethrough or reflect, a front monitor for receiving the light beam emitted from the laser diode, and a front monitor light-guiding plate for guiding a part of the light beam emitted from the laser diode to the front monitor. The front monitor light-guiding plate is arranged between the laser diode and the objective lens and has a region having a predetermined shape for causing the part of the light incident thereon to change a traveling direction thereof by refraction and then reach the front monitor.

Abstract: A light source unit comprises a plurality of light sources emitting a plurality of light beams. A plurality of volume hologram elements are provided for the plurality of light sources respectively, each volume hologram element having a plane of incidence of an incoming light beam and a plane of outgoing radiation of a diffracted light beam which are perpendicular to each other, the plurality of volume hologram elements having mutually different Bragg conditions in which an optical intensity of a diffracted light beam is set to a maximum.

Abstract: An optical head which is capable of realizing a stable tracking control, even if the rotational center of an information recording medium is not located on the extension line of the transfer directions of a light-concentrating element, includes: a semiconductor laser which emits a beam of light; an objective lens which concentrates the beam of light on an optical disk; a transfer mechanism which transfers the objective lens between the outermost circumference and the innermost circumference of the recording area of the optical disk along the optical disk; and a photo-detector which detects a beam of light that returns from the optical disk. The photo-detector includes a plurality of areas which are divided by a division line.

Abstract: To read information from a target information recording surface reliably by canceling DC offsets in tracking-signal detection signals is provided. In effecting tracking servo by 3-beam method, auxiliary light receiving domains D3—1, D3—2, D8—1, D8—2 are provided. The auxiliary light receiving domain receives images formed by the light returned from a different information recording surface from the one targeted for reading. Sub beams of ± first-order diffracted light enter the light receiving domains D3, D8, D1, D10. With respect to the diffraction direction of the hologram, the auxiliary light receiving domains D3—1, D3—2 (D8—1, D8—2) are provided on both sides of the light receiving domain D3 (D8). Since signals are computed as: D8?(D8—1+D8—2); and D3?(D3—1+D3—2) with the internal connection, DC offsets can be canceled in RES signals (D1+D3, D8+D10) used in the DPP method.

Abstract: The objective of this invention is to provide a type of photodiode and the method of manufacturing the photodiode characterized by the fact that it has a higher photoelectric conversion efficiency (sensitivity) than that in the prior art. PIN photodiode 100 has a p-type silicon substrate, p-type silicon layer 112, n-type silicon layer 114 formed on p-type silicon layer 112 and having a junction plane with silicon layer 112, n-type low-resistance silicon region 116 that is formed to a prescribed depth from the surface of silicon layer 114 and has an impurity concentration higher than that of silicon layer 114, silicon oxide film 120 formed on silicon region 116, and silicon nitride film 122 formed on silicon oxide film 120.

Abstract: The invention relates to a light-receiving element for receiving a reflection of laser light irradiated to a rotating multi-layer recording medium having a plurality of information recording layers stacked one over another and for converting the light into an electrical signal, an optical head having the element for recording information in the multi-layer recording medium or reproducing information recorded therein, and an optical recording/reproducing apparatus and a method of optical recording and reproduction. The invention provides a light-receiving element, an optical head, an optical recording/reproducing apparatus, and a method of optical recording and reproduction which make it possible to eliminate a noise component superimposed on reflected light from a multi-layer recording medium to reproduce an RF signal of high quality.

Abstract: An optical pickup device comprises a photodetector for receiving laser light reflected from a disc and a housing in which the photodetector is housed, and the photodetector is directly attached to the housing. Through the use of the optical pickup device, occurrence of positional deviation of the photodetector can be suppressed, even under greatly changing temperatures.

Abstract: A method for recording address information on an optical recording medium, and the optical recording medium are discussed. According to an embodiment, there is provided an optical recording medium including a wobble-shaped recording track that is formed thereon based on a wobble signal, the wobble signal being modulated by a predetermined modulation method, wherein a physical address information is included in the wobble modulation, data bit “0” and “1” comprising the physical address information being comprised of a 2n+4 (n?0)-wobble basis and being distinguished from each other such that each data bit has at least three same values and at least one different value in the modulated wobble signal with respect to the 2n+4 (n?0)-wobble basis.

Abstract: An optical pickup device and an optical recording and reproducing apparatus are suitable for use with a near-field optical recording and reproducing system. An optical pickup device comprises an objective lens composed of a solid immersion lens (SIL) the objective lens having a numerical aperture greater than 1, a beam splitter configured to reflect both of a p-polarized light component and an s-polarized light component of reflected lights from an optical recording medium when the optical pickup device irradiates the optical recording medium with a bundle of rays in a predetermined polarized state from a light source through the objective lens, a divider configured to divide incident light into a p-polarized light component and an s-polarized light component reflected by the beam splitter, and a photo-detector configured to separately detect the p-polarized light component and the s-polarized light component divided by the divider.

Abstract: A surface-condition-information obtaining unit obtains information on a surface condition of a rewritable display medium on which information is reversely displayed visually. A write-laser output unit outputs a write laser to irradiate the rewritable display medium with the write laser, to perform a drawing on the rewritable display medium. A control unit performs a write process for displaying an image on the rewritable display medium by adjusting a laser output condition based on the information obtained by the surface-condition-information obtaining unit and controlling the write-laser output unit based on an adjustment of the laser output condition.

Abstract: A semiconductor light receiving element has: a semiconductor substrate; a plurality of photodiodes formed on the semiconductor substrate and configured to receive respective lights of different wavelengths; and an anti-reflection film provided on light receiving surfaces of the plurality of photodiodes. A structure of the anti-reflection film on at least one photodiode of the plurality of photodiodes is different from a structure of the anti-reflection film on another photodiode of the plurality of photodiodes.

Abstract: In an HD-DVD, record densities are different between in a lead-in area and in a data area. On the other hand, in a DVD, the record densities of a lead-in area and a data area are equal. In discriminating an optical disc between the HD-DVD and the DVD, a light beam having a wavelength for the HD-DVD or for the DVD is projected onto the respective areas of the lead-in area and the data area, and a comparison is made between the amplitude of a tracking error (TE) signal obtained on the basis of reflected light from the lead-in area and that of a TE signal obtained on the basis of reflected light from the data area. When the difference between both the amplitudes is within a predetermined range, the optical disc is discriminated as the DVD, and when the difference between both the amplitudes is larger than the predetermined range, the optical disc is discriminated as the HD-DVD.

Abstract: An optical disk device has a light source which emits light; and light converging means of, in each of signal mark forming regions, each of lands, or each of grooves of an optical disk, converging the light from the light source onto a signal surface of the optical disk with selectively positioning a signal mark at any one of plural positions which are arranged in a direction that is substantially perpendicular to tracks, each of the signal mark forming regions surrounded by adjacent two of boarder lines which are between two the tracks on the signal surface of the optical disk, and which are substantially parallel to the tracks, and each of which substantially divides an area between adjacent tracks in two parts.

Abstract: An semiconductor laser light source apparatus includes: a semiconductor laser oscillator for emitting a laser beam; and a lens for transmitting the laser beam emitted by the semiconductor laser oscillator, wherein the lens comprises a light transparent material in which microparticles are dispersed into a plastic resin and have a size of the transmitting laser beam wavelength or below.

Abstract: A laser diode driving circuit and a laser diode controlling apparatus including the laser diode driving circuit. The laser diode driving circuit includes a voltage drop prevention unit, which prevents a voltage at an input terminal of the laser diode driving circuit from dropping to a predetermined voltage level or lower, the input terminal of the laser diode driving circuit being connected to an output terminal of the ALPC circuit.

Abstract: An optical pickup for recording and/or reproducing data with respect to a multilayer recording medium having a plurality of recording layers, where the optical pickup includes a light source emitting a beam having a predetermined wavelength, a diffraction unit separating the beam emitted from the light source into a main beam and a sub-beam, and a photodetector having a main photodetector detecting a main beam reflected from the multilayer recording medium and a sub-photodetector detecting the sub-beam. In the optical pickup, the main photodetector and sub-photodetector are separated a predetermined distance from each other so that a beam spot formed by the beam reflected from a defocus recording layer is not detected by the sub-photodetector.

Abstract: An integrated optical head records and reproduces information to and from optical discs of different types, including CD and DVD, with use of a single information recording/reproducing apparatus. The optical head has a plurality of semiconductor lasers of different wavelengths integrated by index alignment onto a substrate formed with an optoelectric integrated circuit, photodetection patterns, and a reflecting mirror.

Abstract: An optical head in which pre-formatted signals may be detected as variations in the amplitude or the phase in the pre-formatted signals are suppressed, and a recording and/or reproducing apparatus employing the optical head, are disclosed. The optical head includes a light source 212, an objective lens 220 for condensing a light beam radiated from the light source 212 on a recording track of an optical recording medium 102, and a photodetector unit 223 for receiving the light beam reflected back from said recording track. The photodetector unit 223 includes a first light receiving section 230b and a second light receiving section 230c.

Abstract: An optical pickup in which a plate 2 provided with a photodiode 22 is bonded to an optical bench 1 through an adhesive agent layer 3 in a state in which a minute gap ? is maintained between the plate 2 and the optical bench 1. Circular through holes 27 are formed in advance at a plurality of portions of the plate 2. The adhesive agent layer 3 is formed as an adhesive agent injected into the through holes 27 at the plurality of portions is forced out downward through the through holes 27 and is cured in the state of having reached an upper surface 12 of the optical bench 1. The amount of the adhesive agent injected with respect to each of the through holes is controlled so as to be fixed.

Abstract: An optical disc apparatus is provided, which comprising a laser light emitting portion for generating laser light for irradiating an optical disc, and a laser control portion for controlling a light emission operation of the laser light emitting portion. The laser control portion causes the laser light emitting portion to emit light with a first period during a first operation, and the laser control portion causes the laser light emitting portion to emit light with a second period during a second operation. The first period and the second period are different from each other.

Abstract: An optical pickup for a recording medium includes a light beam division and detection unit including receiving portions dividing an incident light beam reflected on the recording medium into a first light beam portion and a second light beam portion around the first light beam portion and converting the first and second light beam portions into first and second detection signals, respectively. A thickness variation detection circuit detects a variation in thickness of the recording medium according to the first and second detection signals and outputs a thickness variation signal indicative thereof.

Abstract: An optical scanning device incorporating a compound objective lens 10 and a radiaion detector 31 is described for reading an optical record carrier 1 in which the optical record carrier 1 is provided with a transparent layer 2. The thickness of the transparent layer 2 and the effective radius of the detector 31 are adapted such that the signal-to-noise ratio of the device is significantly improved and/or local heating of an air gap below an air slider is reduced. The optical record carrier is provided with a lubricant to facilitate the use of a slider optical head 40.

Abstract: A low voltage differential signaling transmitting circuit includes a driver circuit that outputs currents as differential signals from its pair of output terminals in accordance with a digital signal input to its input terminal, a bias circuit that supplies the driver circuit with a bias current so as to adjust values of the currents output from the driver circuit, a current/voltage conversion circuit that converts the currents output from the pair of output terminals of the driver circuit into voltages, and a receiver circuit that compares the voltages with each other and outputs a signal representing a result of the comparison. The bias circuit and the current/voltage conversion circuit are arranged on a same semiconductor chip.

Abstract: In an optical pickup device, a flexible substrate (FPC) (2) and an auxiliary board (4) are fixed to an optical unit (5) with screws (11) before fixing an optical detector (1) to the FPC (2). After that, the optical detector (1) is pressed to the FPC (2) by probes (12), to bring lead portions (1a) into contact with conductor portions (2a). The optical detector 1 is singly moved by the probes (12) in that state, to perform position adjustment of the optical detector (1). Since the friction between the optical detector (1) alone and the FPC (2) is small, the position adjustment can be performed with high accuracy. Further, since the lead portions (1a) and the conductor portions (2a) are in contact with each other, it is possible to perform the position adjustment while observing an electrical signal outputted from the optical detector (1) through the FPC (2).

Abstract: An optical pickup apparatus includes a light source module which emits a light beam, a beam splitter which reflects or transmits the light beam emitted from the light source module, an objective lens which focuses the light beam passing through the beam splitter onto a disc, and a photodetector which receives and detects the light beam reflected by the disc, wherein the light source module includes a first light source and a second light source that emit first and second light beams having different wavelengths and are formed into a single module. The optical pickup apparatus further includes a first grating which divides the first light beam emitted from the first light source into three beams of the first light beam and transmits the second light beam emitted from the second light source, and a second grating which transmits the first light beam emitted from the first light source and divides the second light beam emitted from the second light source into three beams of the second light beam.

Abstract: A high-density data storage medium, a method of manufacturing the data storage medium, a high-density data storage apparatus, and methods of writing data on, and reading and erasing data from the data storage medium by using the data storage apparatus are provided. The data storage medium includes a lower electrode, an insulation layer deposited on the lower electrode, a photoelectron emission layer deposited on the insulation layer and having a plurality of protrusions from which photoelectrons are emitted due to collisions between the protrusions and photons, and a dielectric layer deposited on the photoelectron emission layer and storing the photoelectrons emitted from the photoelectron emission layer.

Abstract: The present invention realizes a compact and thin light-receiving device in a simple configuration, and provides a compact optical head on which this light-receiving device is mounted. The light-receiving device for receiving light reflected from an information recording medium includes a light-receiving chip having a plurality of electrodes and a flexible wiring board on which the light-receiving chip is mounted and fixed. The plurality of electrodes are connected electrically to the flexible wiring board by attaching directly or via a metal wire.

Abstract: Small-sized and light-weighted optical pickup apparatus capable of eliminating the effect due to the flaring light rays and performing the signal detection of high reliability is provided. In the apparatus, the quarter-wave (?/4) plate and the reflection-type birefringent prime provided with the deflecting function of deflecting the reflection light rays reflected on the optical information recording medium and the light rays flux separating function of separating the reflected light rays from the outgoing light rays are disposed in the optical path between the semiconductor laser constructing the optical pickup portion and the objective lens, and the light-receiving element for receiving the reflection light rays from the optical information recording medium which are defleced and separated by the reflection-type birefringent prism is disposed on a single (same) substrate together with the semiconductor laser.