Abstract: A method for arranging conducting lines of a flexible cable in an optical disk drive first confirms the pins having similar functions of all chips on a main board and a sub-board, and uses only one conducting line of the flexible cable to connect these pins. Therefore, the number of the conducting lines of the flexible cable can be reduced.

Abstract: A line light source system includes a line light source formed by a number of linearly arranged light emitting elements. A pair of cylindrical lenses converges the light bundles emitted from the respective light emitting elements in a direction perpendicular to the direction in which the light emitting elements are arranged, and a pinhole array limits the angle of divergence of the light bundles emitted from the respective light emitting elements with respect to the optical axis of the cylindrical lenses in a direction parallel to the direction in which the light emitting elements are arranged.

Abstract: An optical pickup device includes a frame F in which an integrated optical unit equipped with a semiconductor laser diode is incorporated and a flexible substrate F having a short-circuit wiring pathway connecting two connectors and a driving circuit. The short-circuit wiring pathway is connected to the integrated optical unit and the driving circuit at a minimum distance through the connector in such a manner that the flexible substrate F is incorporated so as to be wound along the frame F. Consequently, recording processing and the like can be stably performed.

Abstract: A first light ray with a wavelength ?1 emanating from the first emission light source passes through the transparent substrate and is condensed by the objective lens on a signal surface of a first optical disk with a substrate thickness t1, a second light ray with a wavelength ?2 (??1) emanating from the second emission light source passes through the transparent substrate and is condensed by the objective lens on a signal surface of a second optical disk with a substrate thickness t2, a step structure of at least one step is formed along a circle or an ellipse on a surface of the transparent substrate, and and by the step of the step structure, a phase of the first light ray is shifted by 2?n1+?1 and a phase of the second light ray is shifted by 2?n2+?2.

Abstract: An optical scanning device is used for scanning first and second information layers with first and second radiation beams. The device includes a radiation source and an objective lens assembly (31). The lens assembly includes a doublet-lens system (61, 62) including a first objective lens (61) with a first cross-section having a first diameter (d1) and a second objective lens (62) with a second cross-section having a second diameter (d2). The first and second lenses are arranged for transforming the first radiation beam to a first focused radiation beam having a first numerical aperture. The objective lens assembly further includes a third objective lens (63) for transforming the second radiation beam to a second focused radiation beam having a second, smaller numerical aperture. The second and third objective lenses (62, 63) are integrally formed in one body (64). In a preferred embodiment of the objective lens assembly, the second diameter is smaller than the first diameter.

Abstract: In fabricating a monochromic and highly coherent light source, no single crystalline bulk semiconductor is used, but two different kinds of transparent substances are alternately stacked over each other to constitute a periodic structure in ½ of the intended wavelength. At least one of the two kinds of transparent substances is controllable in electric conductivity, and the structure is such that inside a medium consisting of this kind of transparent substance light-emitting semiconductor particulates are embedded. Accordingly, a light-emitting device has this structure, which makes possible control of the center wavelength of light emission, the width of wavelength distribution and coherence by adjusting the geometrical parameters of the device without having to alter the kind of material use.

Abstract: It is an object of the present invention to provide an optical pickup apparatus which is capable of supporting multiple wavelengths in a reduced size without using a combined prism. An apparatus includes light emitting means having a plurality of integrated light emitting portions for emitting laser beams of different wavelengths, the light emitting means being adapted to selectively emit one of the laser beams of different wavelengths; photodetecting means for detecting the laser beam; and an optical system for directing the laser beam emitted from the light emitting means to the disc, and for directing the laser beam reflected by the disc to the photodetecting means, wherein the light emitting means is positioned such that a straight line connecting respective light emitting points of the plurality of light emitting portions is coincident with a tangential line of a track on a disc to be reproduced.

Abstract: An optical head includes a light emitter/detector to emit a laser light towards an optical disc and to detect a return light from the optical disc, a diffraction grating to split the laser light into three beams, and a light converging optical system to focus the laser light on a recording surface of the optical disc. The diffraction grating has formed therein a plurality of slits formed whose depth is selected so that the efficiency of diffraction of first-order light when a first light beam is incident upon the diffraction grating is higher than that when a second light beam having a longer wavelength than the first light beam is incident upon the diffraction grating.

Abstract: A semiconductor light-emitting device has a semiconductor layer containing Al between a substrate and an active layer containing nitrogen, wherein Al and oxygen are removed from a growth chamber before growing said active layer and a concentration of oxygen incorporated into said active layer together with Al is set to a level such that said semiconductor light-emitting device can perform a continuous laser oscillation at room temperature.

Abstract: The astigmatic aberration in an optical system is to be adjusted. Specifically, in an optical disc device on which can be selectively loaded a first optical disc having a first index of double refraction or a second optical disc having a second index of double refraction larger than said first index of double refraction, and which includes a liquid crystal device 31 between a light source 11 and an objective lens 15 converging a light beam radiated from said light source on the optical disc 2 loaded on the optical disc device, the voltage applied to the liquid crystal device 31 is adjusted to correct the coma aberration or the astigmatic aberration for the first disc or the second disc, respectively.

Abstract: An optical head for near-field recording and reproduction, and a method of manufacturing the optical head. A vertical cavity surface emitting laser (VCSEL) and a photodetector are formed on a slider, and a lens layer, an optical path control layer and/or a coil member are directly formed over the VCSEL and the photodetector by thin film deposition. Combining the optical system for information recording and reproduction with the slider reduces the size of the optical head compared with an optical head adopting a slider and a large optical system which are separated from each other. As a result, dynamic characteristics of the optical head improve, thereby reducing the time required for searching for a target track. Thus, the optical head is suitable for a micro information recording and reproducing system.

Abstract: In an optical pickup projecting a laser beam from a laser diode onto a disk through a half mirror, a collimator lens and an objective lens and receiving the laser beam reflected by the disk in a photodiode through the half mirror thereby reading information recorded in the disk, a portion of a metal board body having a pattern of a printed board corresponding to a connector pin fed with a high-frequency signal is notched to cause no electrostatic capacitance between the metal board body and the printed board thereby preventing a read signal from the photodiode from a jitter. Thus obtained is a high-performance and low-priced optical pickup causing no reading error.

Abstract: A semiconductor laser element has the following configuration: a dual-wavelength monolithic laser where semiconductor lasers with emission wavelengths of 650 nm and 780 nm are integrated on one chip is soldered on a heat sink which then is soldered on a can package. Two beam emission points of the semiconductor laser element are positioned so that beam spots, formed on an optical disk, of light beams emitted from the two semiconductor lasers are aligned substantially along a pit-row direction in the optical disk. Thus, an optical head device and an optical recording and reproducing apparatus can be obtained that can record information on or reproduce recorded information from optical information recording media with different optical characteristics and recording densities from one another and that do not cause instability in tracking servo operation.

Abstract: Laser beams respectively emitted from a SHG blue laser unit and a red semiconductor laser unit that have photo detectors respectively are turned into parallel lights by a collimator lens and then coupled by a dielectric multi-layer film mirror so as to be propagated on the same optical axis. The dielectric multi-layer film mirror is configured so as to transmit light with a wavelength of 500 nm or shorter and reflect light with a wavelength of 500 nm or longer for both P wave and S wave. The lights that are transmitted and reflected by the dielectric multi-layer film mirror pass through a polarizing hologram and a phase variable wave plate and are focused on an optical disk by an objective lens. In this manner, a simple configuration can realize a compatibility with many types of optical disks and a stable signal detection even when using a polarizing optical detection system.

Abstract: Methods of writing information to an optical memory device. The methods comprise the step of writing a mark to the active material of the optical memory device by irradiating the material with an applied energy source. In one embodiment, the applied energy source provides a plurality of energy pulses. In another embodiment, energy in excess of that required to form a mark is released and dissipated in a manner that minimizes mark enlargement, spurious mark formation, recrystallization and back crystallization. The methods are effective to provide better cooling characteristics through enhancement of the capacitive cooling contribution.

Abstract: An optical pickup is provided which can read information from a plurality of recording mediums having different wavelengths without the need for a mixing prism. The optical pickup is comprised of a light emission part, a grating, a hologram and a light receiving part. The light emission part emits first and second laser beams having different wavelengths from each other. The grating generates a pair of sub-beams from the laser beam emitted from the light emission part. The hologram generates first and second high-order beams from the laser beam reflected by a recording medium to guide the high-order beams to the light receiving part. The light receiving part receives the first and second high-order beams generates a focus error signal and a tracking error signal which enables the information to be correctly read from the different recording mediums.

Abstract: Light from a laser diode is directed by mirrors on angled surfaces of an optical unit through a first lens at an optical disc. Light returns from the disc on a parallel path through a second lens and is directed at a photodetector. A semiconductor device controls the operation of the laser diode and receives signals form the photodetector for processing. The optical unit is formed from one or two glass elements cut from a larger glass wafer or wafers using photolithographic techniques. The mirrors are formed by thin films deposited on angled glass surfaces formed by selective plasma etching of the wafers. At least one mirror is partially reflective and is formed by depositing a thin film of titanium nitride.

Abstract: An optical head in which a plurality of semiconductor laser chips are adhered on a mount surface perpendicular to the tracking servo direction of a focusing lens. Fluctuation of an optical spot power is reduced even if the tracking servo is performed by the optical head having dispersion of an inner surface direction when a plurality of the semiconductor laser chips are mounted. In FIG. 1, a plurality of the semiconductor laser chips 4a and 4b are arranged so as to have a mounting direction which is substantially perpendicular to the tracking servo direction of the focusing lens.

Abstract: An optical head for reproducing information contained on an optical information disk includes a plurality of light sources and a plurality of light receiving elements in correspondence with the plurality of laser light sources. There is constructed a constitution in which one laser light source in the plurality of laser light sources is constituted by an individual laser diode and which includes a laser module constituted by other laser light sources and the plurality of light receiving elements to thereby enable to realize the small size of the optical head.

Abstract: A semiconductor laser device and optical pickup in which the reflectance of the side beam at a header portion will not adversely affect the characteristics of the optical pickup, and superior in productivity, and a method of fabricating such a semiconductor laser device are obtained. A reflector is attached on a side beam incident region of a leading end plane of a header mounted with a laser chip that emits a laser beam. Said side beam is one of the two side beams generated by the reflected ±first order beams and fed back through the optical system returning towards the header portion to strike the side beam incident region. The reflector reflects side beam outside the optical system.

Abstract: An optical pickup device is adapted to read information signals from optical recording media of two different types such as a “DVD” and a “CD” for which two light beams with different wavelengths are used and comprises a photodetector having a single light receiving section that can be shared by optical recording media of two different types. Both the light beam reflected from the signal recording surface of the “DVD” 106a and the light beam reflected from the signal recording surface of the “CD” 106b are diffracted by the diffraction element 6 and focussed to a same spot on the light receiving surface of the photodiode of a photodetector 7.

Abstract: Disclosed are a light emitting module, an optical detecting module, an optical pickup apparatus formed by coupling the ultra-minimized light emitting module and the optical detecting module, and manufacturing methods thereof. To this end, ultra-minimization, a micro machining technique fit to a mass production, and a semiconductor device assembly manufacturing process are applied, thereby reducing a component cost and increasing uniformity of components.

Abstract: A method of mounting an optical device having a step on the surface opposing to a mounting substrate favorably by face-down bonding which enables a decrease in the number of components or integrate additional components on one identical substrate and, accordingly, is useful for reducing the size and the thickness of an optical head using a light source, the method includes the step of making the volume of a solder pattern to the area ratio of each electrode different for every wiring electrode portions upon mounting the electrodes on the substrate for mounting the optical device, in which the optical device having the step can be mounted favorably to the substrate by the control for the height of solder upon melting.

Abstract: A near-field optical apparatus having one or more solid state lasers and an aerodynamically shaped slider which comprise a single integrated, monolithic device fabricated from the same base semiconductor material. The monolithic optical head can be quickly and easily attached to the read arm of an optical read/write device without requiring attachment of separate laser elements, and without micropositioning or use of optical microscopy for positioning the lasers. The optical head comprising a single semiconductor substrate including a first region which defines a slider having an air bearing surface, and at least one second, laser region which defines a diode laser, with the diode laser having an emission face which is substantially co-planar with the air bearing surface.

Abstract: In an optical semiconductor package according to the present invention, the component bearing surface of the stem having an outline made up of opposed first and second circular-arc parts, a first straight-line part which connects each end of the first and second circular-arc parts and a second straight-line part which connects each other end of the first and second circular-arc parts. The first and second circular-arc parts have a common center, and the first circular-arc part has a larger radius than that of the second circular-arc part. Thus, the larger space, the space between the first circular-arc part and the center, can be used for disposing the light detector or a polarization split element, and the unused space, the space between the second circular-arc part and the center, will be minimum, thereby realizing downsizing and cost reduction of the device.

Abstract: An aperture 12 for producing an evanescent wave is provided at an n-Au electrode 106. The aperture 12 is directed roughly perpendicularly to a direction in which end faces 104a of an active layer 104 of an optical device oppose to each other, and therefore, laser light generated in the active layer 104 is made incident in the form of the p-polarized light. By the incidence of the p-polarized laser light, an evanescent wave of a comparatively great intensity is obtained from the aperture 12. With this arrangement, an optical device capable of obtaining an evanescent wave of a comparatively great intensity is provided.

Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted

Abstract: An optical recording medium is arranged such that respective information recorded on lands and grooves are reproducible by either of a light beam of a first wavelength ?1 and a light beam of a second wavelength ?2 which is shorter than the first wavelength ?1. The groove depth d of the optical recording medium is such that tracking error signals of not less than a predetermined level can be ensured for respective wavelengths ?1 and ?2 without generating distortion in waveform, irrespectively of differences in receiving light sensitivity of a photodetector provided in a optical pickup devices for use in recording and reproducing information on and from such optical recording medium.

Abstract: A data storage device includes a phase-change storage layer and an array of nanotubes as electron sources.

Abstract: A monolithic double-wavelength semiconductor laser diode is provided in a DVD/CD compatible player to suppress deterioration in the optical characteristics of a reading light spot. A laser diode is a monolithic element which has two light emitting points on a single substrate for emitting two different laser beams having different wavelengths with each other. A central line of a main laser beam for use in reproducing DVDs is positioned closer to the optical axis Y of an optical system than a central line of a laser beam for use in reproducing CDs. In another arrangement, the central line of a main laser beam for use in reproducing DVDs is positioned so as to be coincident with the optical axis Y of the optical system.

Abstract: A semiconductor laser unit includes a plurality of semiconductor laser elements arranged parallel with one another in a laser beam-emitting direction, and a base for positioning and fixing the plurality of semiconductor laser elements. The plurality of semiconductor laser elements are arranged such that a laser beam emitted from the semiconductor laser element greatest in astigmatism, of the plurality of semiconductor laser elements, is coincident in its axis with a reference axis of the base. In the case that the semiconductor laser unit is arranged on an optical head device, the focusing characteristic on the plurality of laser beams can be improved.

Abstract: An optical pickup device 20 comprises an objective lens, a light source 1 composed of a blue semiconductor laser with a wavelength ranging from 400 to 415 nm and a collimator lens 2 for collimating light L1 from this light source 1 to provide substantially-collimated light, wherein Abbe number v of a glass material of the collimator lens 2 satisfies 61<v<90, a linear expansion coefficient ? satisfies 55<107×?/K<120, and a refractive index temperature coefficient (dn/dt) satisfies ?1.8<106×(dn/dt)/K<+1.5. Since the position at which the focal point of the collimator lens 2 was displaced due to fluctuation of temperature and fluctuation of wavelength can be compensated for at high accuracy, the optical pickup device can increase recording density and storage capacity of an optical recording medium.

Abstract: An optical head includes a light emitter/detector to emit a laser light towards an optical disc and to detect a return light from the optical disc, a diffraction grating to split the laser light into three beams, and a light converging optical system to focus the laser light on a recording surface of the optical disc. The diffraction grating has formed therein a plurality of slits formed whose depth is selected so that the efficiency of diffraction of first-order light when a first light beam is incident upon the diffraction grating is higher than that when a second light beam having a longer wavelength than the first light beam is incident upon the diffraction grating.

Abstract: Metal-insulator-metal planar electron emitters (PEES) have potential for use in advanced lithography for future generations of semiconductor devices. The PEE has, however, a limited lifetime, which restricts its commercial applicability. It is believed that the limited lifetime of the PEE is limited by in-diffusion of metal ions from the anode. The in-diffusion may be countered in a number of different ways. One way is to cool the PEE to temperatures below room temperature. This lowers the metal ion mobility, and so the metal ions are less likely to diffuse into the insulator layer. Another way is to occasionally reverse the electrical potential across the PEE from the polarity used to generate the electron beam. This counteracts the electrical driving force that drives the positively charged metal ions from the PEE anode to the PEE cathode.

Abstract: A three-dimensional vertical memory with florescent photosensitive vitreous material is read and written to by a laser or respective lasers. The memory can be cerium and europium-doped fluorescent photosensitive glass, yttrium, europium and praseodymium-containing glass or TV-doped glass, etc. A confocal microscope may be used in the writing process and the memory may be scanned by rotating it.

Abstract: An optical pickup apparatus comprises a first light source for emitting a first laser beam having a first wavelength; a second light source for emitting a second laser beam having a second wavelength; and an objective lens for condensing the first laser beam and the second laser beam. The first light source and the second light source are disposed in positions in such a way that a total amount of coma aberration, which is generated on the first laser beam in accordance with a distance between the first light source and an optical axis of a whole optical system and coma aberration, which is generated on the first laser beam in accordance with a tilting amount of the objective lens becomes null, and a total amount of coma aberration, which is generated on the second laser beam in accordance with a distance between the second light source and said optical axis and coma aberration, which is generated on the second laser beam in accordance with the tilting amount of the objective lens becomes null.

Abstract: An optical pickup has a base having a screw hole, a holder attached to the base, a laser diode held by the holder, a leaf spring, and an adjusting screw. The holder is formed of a substantially rectangular metal plate having short and long sides and is formed with a laser hole for fitting the laser diode through a center thereof. An angular fulcrum is formed at the center of a back surface of the holder along a direction parallel to the short side. The fulcrum is brought into abutment with the base via the leaf spring and one end of the holder is urged toward the base by the leaf spring. The holder is temporarily secured to the base by screwing the adjusting screw through an insertion hole formed at the other end of the holder into the screw hole of the base.

Abstract: An aperture 12 for producing an evanescent wave is provided at an n-Au electrode 106. The aperture 12 is directed roughly perpendicularly to a direction in which end faces 104a of an active layer 104 of an optical device oppose to each other, and therefore, laser light generated in the active layer 104 is made incident in the form of the p-polarized light. By the incidence of the p-polarized laser light, an evanescent wave of a comparatively great intensity is obtained from the aperture 12. With this arrangement, an optical device capable of obtaining an evanescent wave of a comparatively great intensity is provided.

Abstract: An optical head with high light utilization efficiency that includes a diffractive optical element and a light source emitting beams with a plurality of wavelengths that can read plural types of information recording media. A beam emitted from a light source selectively emitting a beam with a first wavelength and a beam with a second wavelength that is approximately twice as long as the first wavelength is collimated into a parallel beam by a diffraction collimator lens, is bent by a mirror for bending an optical path, and then is focused by a diffraction objective lens on an information recording medium. Outgoing light from these diffractive lenses is substantially a second-order diffraction light with respect to the beam with the first wavelength and is substantially a first-order diffraction light with respect to the beam with the second wavelength.

Abstract: The present invention relates to an optical pickup, and more particularly to an optical pickup, which can promptly process optical disk information using a light source module for selectively generating light beams with different wavelengths, such as 650 nm, 780 nm and 405 nm, and an optical modulator for reflecting and diffracting an incident light beam to generate multiple beams.

Abstract: Guide members for guiding an optical pickup for movement in directions parallel to a diameter of an optical disk relative to the optical disk are formed of a metal, support members supporting the guide members on a chassis are formed of a resin, and heat transfer members formed of a metal are set in contact with the guide members and the chassis to achieve both the dissipation of heat generated by the optical pickup and the isolation of the optical pickup from vibrations. The guide support members attenuate vibrations propagating from the chassis toward the optical pickup, and heat generated by the optical pickup is dissipated through the heat transfer members into the chassis.

Abstract: Laser beams respectively emitted from a SHG blue laser unit and a red semiconductor laser unit that have photo detectors respectively are turned into parallel lights by a collimator lens and then coupled by a dielectric multi-layer film mirror so as to be propagated on the same optical axis. The dielectric multi-layer film mirror is configured so as to transmit light with a wavelength of 500 nm or shorter and reflect light with a wavelength of 500 nm or longer for both P wave and S wave. The lights that are transmitted and reflected by the dielectric multi-layer film mirror pass through a polarizing hologram and a phase variable wave plate and are focused on an optical disk by an objective lens. In this manner, a simple configuration can realize a compatibility with many types of optical disks and a stable signal detection even when using a polarizing optical detection system.

Abstract: A write once optical recording medium and a method and apparatus for storing and recovering defect management information to and from the write once optical recording medium are provided. The recording medium includes at least one recording layer, and a data area on the recording layer. The data area includes at least one spare area and a user data area. The spare area contains at least one replacement cluster, each of the replacement clusters storing therein address information of a corresponding defective cluster.

Abstract: The optical pickup apparatus 100 uses a semiconductor laser element 50 integrated a first light emission source 36 for emitting a first laser beam with a second light emission source 40 for emitting a second laser beam, of which wavelength is different from that of the first laser beam. The optical pickup apparatus 100 is constructed so that a first half mirror functional surface 52b and a second half mirror functional surface 52c are provided in a beam splitter 52 to match an optical path in which the first laser beam passes through the first half mirror functional surface 52b of the beam splitter 52 and then is reflected at the second half mirror functional surface 52c and again is emitted from the first half mirror functional surface 52b to be directed toward a bifocal lens 54 with an optical path in which the second laser beam is reflected at the first half mirror functional surface 52b to be directed toward the bifocal lens 54.

Abstract: An optical fiber array is constructed by using a plurality of laser modules, which guide a laser beam emitted from a semiconductor laser of a blue color wavelength to an optical fiber, such that beam emitting ends of respective optical fibers are aligned in one row at an equal interval, and the laser beam being output from the optical fiber array is used as a multibeam of an optical recording apparatus. A relative refractive index difference of the used optical fiber is set between 0.1% to 0.2%, and a core diameter is set to 4.5 &mgr;m or less, and also a mode field diameter of the optical fiber, i.e., a diameter of a beam spot emitted from the optical fiber is set to 3 &mgr;m or more.

Abstract: There is provided an optical system of an optical pick-up for recording/reproducing data to/from at least two types of optical discs including a first optical disc and a second optical disc whose recording density is higher than that of the first optical disc. The optical system is provided with a light source unit for the first and second optical discs, an objective lens, and a photo detector. The optical system further includes an optical surface to satisfy compatibility between the at least two types of optical discs, the optical surface being located between the light source unit and one of the at least two type of optical discs. The optical surface has an inner region having a numerical aperture for the first optical disc, an outer region located having a numerical aperture for the second optical disc, and an intermediate region that is located within the outer region at a periphery of the inner region.

Abstract: An optical recording medium is provided with a recording layer and a reflecting film on an optically transparent substrate. The principal component of the recording layer is a dye. Virtual recording cells are assumed within grooves on the recording layer and recording marks with five different levels or more of increasing size are formed on each of the virtual recording cells by modulating the irradiation time of the laser beam in five levels or more in correspondence to the information to be recorded. The reflectance of the virtual recording cells modulates in many levels and the reflection level of the reading laser beam during regeneration is changed in five levels or more. The optically transparent substrate is made of a plastic with a glass transition point (Tg) of 160° C. or less. The reflecting film is a metal with a coefficient of thermal conductivity of 300 k/W·m−1·K−1 or more and a film thickness of 50 nm or more.

Abstract: The storage media recording/writing system includes a media drive circuit, a head retaining means, a head moving means, a head drive circuit, a signal processing circuit, and a controller to control these. The head drive circuit possesses a first semiconductor integrated circuit having an amplifier that amplifies the read signal from the head, and a second semiconductor integrated circuit placed between the first semiconductor integrated circuit and the signal processing circuit, which has a circuit that receives write data from the signal processing circuit and generates a drive signal to drive a write head. Further, the first semiconductor integrated circuit is mounted on a part near the front of the head retaining means, and the second semiconductor integrated circuit is installed on the side of the moving means.

Abstract: A laser diode (LD) driver and method of compensating for a bias driving potential of an LD driver according to a change in a power level of a laser signal from an LD in a recording mode include storing the bias driving potential, detecting a change in a bias power level in the laser signal, and compensating the bias driving potential according to the detected change in the bias power level.

Abstract: In an optical head for writing and reading data on optical discs (mainly CDs and DVDs) with various specifications using different light source wavelengths, the effective light beam size for the light from each light source differs. This leads to a drop in optical efficiency for the light of a narrower effective beam size. This problem is overcome by providing a dichroic beam expander between the light sources and an objective lens, the dichroic beam expander comprising a substrate with an N-stage step- or sawtooth-shaped blazed diffraction grating formed on both sides thereof. The size of the light beams from the two light sources with different wavelengths is increased or decreased in a wavelength-selective manner, so that the light from each light source can be utilized at high efficiencies.