Abstract: An optical system for use in an optical pickup apparatus comprises a first optical surface having a superposition type diffractive structure including a plurality of ring-shaped zones which are formed concentrically around an optical axis, wherein each ring-shaped zone is composed of a plurality of stepped sections stepwise, and a second optical surface having a diffractive structure including a plurality of ring-shaped zones which are formed concentrically around an optical axis, wherein each of the plurality of ring-shaped zones are divided by a stepped section to generate a diffractive light ray of diffractive order whose absolute value is not small than 1 for the light flux.

Abstract: Control powers of a first definition group corresponding to pulse trains to form recording marks, and levels of second definition groups corresponding to the control powers of the first definition group for respective states on a recording medium are set. The laser is driven with drive values corresponding to the control powers selected from the first definition group in the selected level of the second definition group, and emission power detection values are detected. The detection values are stored for respective levels of the second definition groups, and an occurrence of obtaining the detection value is counted for each level of the second definition groups. When any of counter values exceeds a predetermined value, using the detection values stored for one level of the second definition groups corresponding to the counter value, corrected drive values are determined collectively for all the levels of the second definition groups.

Abstract: An optical head comprises a laser holder retaining a laser diode, and a holder support retaining the laser holder, and irradiates an information storage medium with laser light from the laser diode to perform recording/reproduction of information. In this optical head, the laser holder is a frame structure that fixes the laser diode, having an abutment portion protruding from a base side of the frame structure. Also, the holder support has a receiving surface that supports by abutment the abutment portion, and a through-hole that lets pass the laser light. The receiving surface is a plane approximately perpendicular to an optical axis of the optical head, the abutment portion being made as an arc surface having a central axis that passes through an emission point of the laser diode and is perpendicular to the optical axis.

Abstract: A vertical cavity surface emitting laser including a substrate, a first semiconductor multilayer film reflector formed on the substrate, an active region formed on the first semiconductor multilayer film reflector, a second semiconductor multilayer film reflector formed on the active region, an electrode formed on the second semiconductor multilayer film reflector, a light absorption layer, and a light transmission layer. In the electrode, a light emitting aperture is formed. The light absorption layer is formed in a peripheral region of the light emitting aperture, and absorbs emitted light. The light transmission layer is composed of a material which the emitted light can pass through, and formed in a central region of the light emitting aperture. Thicknesses of the light absorption layer and the light transmission layer are selected so that phases of light from the light absorption layer and from the light transmission layer are adjusted.

Abstract: An optical pickup lens includes a first surface to focus laser light for recording/playback on an optical disc, a second surface formed outside the first surface and radiated with laser light for lens tilt detection, and an antireflection coating to transmit the laser light for recording/playback, the antireflection coating being continuously formed on the first surface and a second surface.

Abstract: An optical system for use in an optical pickup apparatus comprises a first optical surface having a superposition type diffractive structure including a plurality of ring-shaped zones which are formed concentrically around an optical axis, wherein each ring-shaped zone is composed of a plurality of stepped sections stepwise, and a second optical surface having a diffractive structure including a plurality of ring-shaped zones which are formed concentrically around an optical axis, wherein each of the plurality of ring-shaped zones are divided by a stepped section to generate a diffractive light ray of diffractive order whose absolute value is not small than 1 for the light flux.

Abstract: The present invention realizes the emission of a high-output short-pulse beam and a reduction in power consumption. A laser control unit (2) of a short-pulse light-source device (1) raises a gate pulse (PG) of a gate signal (SG) supplied to a power supply circuit (5) in such a manner that the gate pulse (PG) rises only for the duration of an extremely short pulse width (T) to include the rise time of a generated pulse (PL) of a pulse signal (SL) supplied to a driving circuit (6). In this way, necessary power can be supplied at the rise timing of the generated pulse (PL), and the power consumption (Pa) can be greatly reduced from the standard power consumption (Pb).

Abstract: Disclosed is an optical recording/reproducing apparatus. The optical recording/reproducing apparatus includes a laser light source capable of emitting pulsed laser light in a mode-locked state in which light beams having different wavelengths are synchronized and the pulsed laser light is oscillated, means for controlling the laser light source to be changed from a state of emitting the laser light in the mode-locked state to a state of emitting continuous-wave laser light, and means for irradiating a recording medium with one of the laser light in the mode-locked state and the continuous-wave laser light.

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: To provide an optical disc device 1, and similar, equipped with a new mechanism to reduce laser light noise due to optical feedback. In an optical disc device 1 in which a laser diode is driven by a high frequency modulation method, optical feedback is returned to the laser diode at a timing at which the phase of the injected carrier density is within one of the following ranges: (1) equal to or greater than the peak phase of the injected carrier density of the laser diode, and equal to or less than the peak phase of the injected carrier density of the laser diode plus 3?/8 (radians); or (2) equal to or greater than the peak phase of the injected carrier density of the laser diode plus 9?/8 (radians), and equal to or less than the peak phase of the injected carrier density of the laser diode plus 2? (radians).

Abstract: An optical device includes a sub-mount 2 mounting first and second semiconductor lasers 1a, 1b and having an onboard part for the semiconductor lasers and an optical-path conversion mirror 7 integrated with each other, and a light receiving element 11 arranged on a light receiving element substrate to have first and second light receiving regions separated from each other by at least one parting line. In the optical device, one light gravity center of an optical spot, which is formed on the light receiving element 11 by homeward flux of light emitted from the first semiconductor laser 1a and reflected by an optical disc 55, and another light gravity center of an optical spot, which is formed on the light receiving element 11 by homeward flux of light emitted from the second semiconductor laser 1b and reflected by the optical disc 55 are together positioned on the parting line.

Abstract: According to the present invention, a recording film is partially initialized using a first light beam (A) having a wavelength for initialization, focus adjustment is performed using a second light beam (B) having a wavelength corresponding to a wavelength for recording and reproducing information on and from an information recording medium, and then the recording film is initialized using the first light beam (A), thereby it is possible to securely initialize recording films of all information layers of a multilayer information recording medium.

Abstract: A light emitting device includes a base, a light-emitting module, and a shielding case. The light-emitting module is fixed to the base via a curved flexible printed-circuit. The shielding case fixed to the base in such a manner that the light-emitting module is held in a position to resist a restoring force of the flexible printed-circuit which is generated by the curve of the flexible printed-circuit. The light-emitting module includes a heat source, and the shielding case includes a projection. The projection controls movement of the light-emitting module in a direction perpendicular to the direction in which the light-emitting module is held by the shielding case. The projection and the light-emitting module are bonded to each other with silicone.

Abstract: The aberration takes place according to the height of the image because the laser light tilts from the optical axis when it enters to the object lens in the optical pickup device which is equipped with a laser diode for BD and the monolithic laser diode capable of irradiating laser lights with two different wavelengths for DVD and CD as one package to read the signal by single object lens and single optical system. This is because the light sources of the three lights with different wavelengths are away from each other in the optical pickup device. The emission point of the laser diode for BD is formed at the location shifted from the center of the chip. The laser diode for BD is disposed adjacent to the monolithic laser diode capable of irradiating laser lights with two wavelengths for DVD and CD to make the emission point closer to the monolithic laser diode. The sizes of these two laser diodes is minimized by employing half dicing during the cleavage processing for separating the chips.

Abstract: An optical pickup includes a first source which emits a first beam with a first wavelength; a second source which emits a second beam with a wavelength shorter than the first wavelength; a first collimate lens which collimates the first beam; a second collimate lens which collimates the second beam; a first objective lens which converges the first collimated beam onto an optical disc; and a second objective lens which converges the second collimated beam onto the disc. The first and second objective lenses are arranged in the disc radial direction. The second objective lens is arranged closer to the side of the disc outer circumference than the first objective lens. The first collimate lens is arranged on the right-hand side when the second objective lens is viewed from the first objective lens. The second collimate lens is arranged on the left-hand side when the first objective lens is viewed from the second objective lens.

Abstract: A laser driving circuit employing a recording compensation circuit configured to generate a light emission timing of a laser on the basis of recorded data and a recording clock signal which are supplied to the recording compensation circuit includes: a phase synchronization circuit; a skew determination circuit; and a data latching circuit.

Abstract: An optical pickup includes: a laser light source which outputs an divergent beam having an elliptical far-field pattern; a beam shaping element having at least one cylindrical plane and which shapes the divergent beam outputted from the laser light source into an divergent beam having a prescribed shape in which at least the length in the major axis direction of the elliptical shape is shortened; a light collecting portion having a beam splitter which perpendicularly collects the divergent beam that is outputted from the beam shaping element and which has a prescribed shape on the recording surface of an optical disk , and a mirror or the like; and a light detecting portion The optical axis of the divergent beam is rotated so that the direction in which the major axis of the divergent beam having a prescribed shape is shortened conforms to the radial direction of an optical information recording medium.

Abstract: An extreme ultraviolet light system includes a drive laser system that produces an amplified light beam; a target material delivery system configured to produce a target material at a target location; a beam delivery system configured to receive the amplified light beam emitted from the drive laser system and to direct the amplified light beam toward the target location; and a metrology system. The beam delivery system includes converging lens configured and arranged to focus the amplified light beam at the target location. The metrology system includes a light collection system configured to collect a portion of the amplified light beam reflected from the converging lens and a portion of a guide laser beam reflected from the converging lens. The light collection system includes a dichroic optical device configured to optically separate the portions.

Abstract: A hologram recording and reproducing device controls an optical beam output from an external cavity semiconductor laser to improve a diffraction efficiency. The hologram recording and reproducing device includes an external cavity laser, a photodiode, a laser drive circuit and a laser diode controller. The external cavity laser has a laser diode adapted to emit an optical beam that is used to generate data light and reference light with which a hologram recording medium is irradiated. The photodiode detects the amount of the optical beam output from the external cavity laser. The laser drive circuit supplies a current to the external cavity laser. The laser diode controller controls the laser drive circuit to ensure that a value obtained by integrating the detected intensity of the optical beam with respect to time over a predetermined period is equal to predetermined recording energy.

Abstract: An extreme ultraviolet light system includes a drive laser system that produces an amplified light beam; a target material delivery system configured to produce a target material at a target location; a beam delivery system configured to receive the amplified light beam emitted from the drive laser system and to direct the amplified light beam toward the target location; and a metrology system. The beam delivery system includes converging lens configured and arranged to focus the amplified light beam at the target location. The metrology system includes a light collection system configured to collect a portion of the amplified light beam reflected from the converging lens and a portion of a guide laser beam reflected from the converging lens. The light collection system includes a dichroic optical device configured to optically separate the portions.

Abstract: A semiconductor laser device has a cathode grounded and an anode connected to a collector of a transistor. The transistor has an emitter grounded and a base connected to a first external terminal via a first resistor. A digital transistor has a collector connected to the base of the transistor, an emitter grounded, and a base connected to a second external terminal via a resistor. When a voltage equal to or higher than the predetermined first voltage is applied to the base of the transistor, the transistor is put into a conducting state, and the semiconductor laser device is grounded via the transistor and thereby protected from static electricity and leak current.

Abstract: An optical pickup apparatus according to the present invention includes: a first light source for emitting a first light flux; a second light source for emitting a second light flux; a third light source for emitting-a third light flux; and an objective optical element. The objective optical element has an optical surface including at least two areas provided with optical path difference providing structures. The objective optical element converges the first to third light fluxes each passing through the predetermined areas on the objective optical element onto respective information recording surfaces of the first to third optical disks. The optical pickup apparatus provides a wavelength dependency of a spherical aberration so as to correct a change in a spherical aberration due to a refractive index change with a temperature change of the objective optical element.

Abstract: A method of manufacturing an optical pickup apparatus, comprising steps of selecting one type objective lens from plural types of objective lenses different in specification of respective optical path difference providing structures in accordance with an oscillation wavelength of a laser light source; and assembling the selected type objective lens and the laser light source into the apparatus.

Abstract: Provided is a highly reliable optical recording head which has a small fluctuation of a quantity of light applied on a recording medium due to temperature. The optical recording head is provided with a light guide section for guiding light applied from a light source, a slider relatively moving to the recording medium, and a light transmitting section, which is arranged on the slider, transmits the light outputted from the light guide section and outputs the light toward the recording medium. The optical recording head is further provided with an adhesive layer, which is sandwiched between the light transmitting section and the light guide section and fixes the positions of the light transmitting section and the light guide section, and an elastic cohesive layer, which is sandwiched between the portions other than the light transmitting section of the slider and the light guide section.

Abstract: The invention relates to the field of optical information recording. In order to prevent abusive or fraudulent use of storage media, the invention provides a process for intentional degradation of information by application of a laser power below the normal power for reading information recorded in super-resolution on the media. This process relies on the surprising observation that a laser power below the super-resolution read power produces an irreversible degradation of the information recorded. This observation has been made with regard to media composed of a three-layer structure comprising an InSb or GaSb layer between two ZnS/SiO2 layers. Application for protecting sensitive data.

Abstract: When a multilayered optical disc is used, the signal-to-noise ratio of a read signal is decreased as effective reflectance is extremely low due to the influence of reflection and absorption by front recording layers. Further, when a high-frequency modulation technology is used to suppress returned light noise of a laser, the erasure of recorded information is likely to occur on certain types of discs, making it difficult to simultaneously achieve the suppression of returned light noise of a laser and the prevention of the erasure of recorded information. To address the above problems, the present invention includes a section that performs a read by executing a multi-tone demodulation. The present invention also includes a section that controls the position and shape of a read light pulse to be radiated on a recording layer.

Abstract: Where a hybrid disc has different types of media, the light spot moves among recording layers of the different media, after loading the disc into an optical disc apparatus, there is a problem that information on a media type of each recording layer should be recorded in DI etc. of the optical disc. Detailed information on the hybrid disc is stored in DI, by changing a disc layer type identifier or a disc structure in DI such as BCA or PIC on the optical disc.

Abstract: An optical pickup device which can improve heat radiation efficiency and an optical disk apparatus including the optical pickup device are provided. The optical pickup device having a base (110), a laser unit (141), an optical system (140) which propagates a laser beam, and an adjusting member (142) includes a heat radiation part (146) which is fixed to a heat radiation surface (141b) of the laser unit and which conducts heat from the heat radiation surface to the adjusting member. Therefore, heat generated by the laser unit is transmitted to the adjusting member and then the base through the heat radiation part to make it possible to efficiently perform heat removal for the laser unit.

Abstract: A hybrid objective lens has a refractive lens and a diffractive optical element constructed by plural coaxial ring-shaped zones on at least one optical surface thereof. When n1, n2 and n3 each is a diffraction order of a diffracted ray having a maximum light amount among diffracted rays of each of first, second and third light flux having wavelength ?1, ?2 and ?3 when respective light flux comes to be incident into the diffractive structure respectively, the following formulas are satisfied: |n1|>|n2|, and |n1|>|n3|, and the hybrid objective lens converges a n1-th, n2-th and n3-th order diffracted ray of the first, second and third light flux onto an information recording plane of each of the first, second ant third optical information recording medium respectively so as to form an appropriate wavefront within respective prescribed necessary image side numerical apertures.

Abstract: An optical pickup includes: a slide base, having: a first surface; and a second surface; a first substrate fixed to the first surface; a standing frame disposed on the second surface; a second substrate facing the standing frame; a laser diode operable to emit a laser beam to the disk and disposed in the standing frame; an optical, element supported by the second substrate and adapted to receive a reflected beam; a flexible flat cable. The flexible flat cable is bent so that one end portion of the flexible flat cable is connected to the second substrate. A curved portion is formed with a slit elongated in a longitudinal direction of the flexible flat cable and defines an outer portion and an inner portion. A width of the inner portion is narrower than a width of the outer portion.

Abstract: An optical information reproducing apparatus includes: an irradiation section irradiating a light beam onto an optical information recording medium, in which holes are formed along a virtual track on a recording medium, along the virtual track; a light receiving section receiving a reflected light beam when the light beam is reflected by the optical information recording medium and sequentially generating a light receiving signal corresponding to the light intensity; a detection section detecting a variation pattern appearing when a signal level of the light receiving signal changes according to the hole; and a code string generating section, when generating a code string corresponding to the signal level, generating a code corresponding to the one hole from the variation pattern if the variation pattern falls within a range and generating a code string, which includes a plurality of codes, from the variation pattern if the variation pattern exceeds the range.

Abstract: An optical pickup apparatus according to the present invention includes: a first light source for emitting a first light flux; a second light source for emitting a second light flux; a third light source for emitting a third light flux; and an objective optical element. The objective optical element has an optical surface including at least two areas provided with optical path difference providing structures. The objective optical element converges the first to third light fluxes each passing through the predetermined areas on the objective optical element onto respective information recording surfaces of the first to third optical disks. The optical pickup apparatus provides a wavelength dependency of a spherical aberration so as to correct a change in a spherical aberration due to a refractive index change with a temperature change of the objective optical element.

Abstract: An optical head includes a first laser diode configured to generate a laser beam with a wave length of ?1, a second laser diode configured to generate a laser beam with a shorter wave length of ?2 than the wave length ?1, a collimator lens arranged so that the laser beams are incident on it, an aperture filter arranged on an optical axis of the collimator lens, and an object lens 0 arranged on the optical axis so that the laser beams passing through the aperture filter are incident on it, wherein the second laser diode is arranged at a position on the optical axis further away from collimator lens than the first laser diode is away from the collimator lens.

Abstract: A media ID recording apparatus has an optical pickup 20 for forming an elongated optical spot on a recording surface of an optical disk DK; and a support table 32 for fixedly supporting the optical pickup 20. The optical pickup 20 is fixed to the support table 32 via a wedge-like spacer 33 as tilted toward the radial direction of the optical disk DK. The focal position of the elongated optical spot at the rear side in the moving direction is matched to the recording surface of the optical disk DK and the focal position of the optical spot at the front side in the moving direction is shifted from the recording surface of the optical disk DK, whereby the light intensity of the optical spot at the front side in the moving direction becomes smaller than the light intensity of the optical spot at the rear side in the moving direction. A media ID is recorded on the optical disk DK by using the optical spot thus set.

Abstract: The present invention realizes the emission of a high-output short-pulse beam and a reduction in power consumption. A laser control unit (2) of a short-pulse light-source device (1) raises a gate pulse (PG) of a gate signal (SG) supplied to a power supply circuit (5) in such a manner that the gate pulse (PG) rises only for the duration of an extremely short pulse width (T) to include the rise time of a generated pulse (PL) of a pulse signal (SL) supplied to a driving circuit (6). In this way, necessary power can be supplied at the rise timing of the generated pulse (PL), and the power consumption (Pa) can be greatly reduced from the standard power consumption (Pb).

Abstract: A small form factor optical disk drive is provided that incorporates a hybrid solid immersion objective lens (SIOL). The SIOL includes a central aspheric lens portion and a surrounding diffractive optical element portion.

Abstract: A small form factor optical disk drive is provided that incorporates a SIL/objective lens assembly. A laser for the small form factor optical disk drive has a coherence function having maxima spaced apart by intervals. The optical disk drive is configured such that a roundtrip optical path through the SIL/objective lens assembly is such that a coherence value for the laser is located in one of the intervals.

Abstract: A single mode laser beam output from a single mode semiconductor laser and a multimode laser beam output from a multimode semiconductor laser are combined with each other by a polarization beam splitter, the combined laser beam is used by a deflection scanning mechanism to perform main scanning, and an image of the combined laser beam is formed on a surface of a thermal recording medium by a scanning lens.

Abstract: The present invention provides a multiwavelength semiconductor laser capable of easily setting reflectance in a predetermined range at different oscillation wavelengths on a main emission edge face side. The multiwavelength semiconductor laser includes a plurality of semiconductor light emission parts of an edge emitting type having different oscillation wavelengths, and a reflection film provided commonly for main emission edge faces of the semiconductor light emission parts. The reflection film includes, in order from the semiconductor light emission parts, a first dielectric film (refractive index n1), a second dielectric film (refractive index n2), and a third dielectric film (refractive index n3), and the refractive indexes n1, n2, and n3 satisfy the relation of n3<n1<n2.

Abstract: There is provided an optical pickup apparatus in which the assembling workability such as chucking of an LD holder by an adjusting jig and spreading of adhesive can be improved. In the optical pickup apparatus, multiple fitting portions (boss portions) 1d formed on one of a side wall surface 1a of a slide base 1 and an LD holder 10 are fitted loosely into respective multiple fitted portions (hole portions) 10b formed in the other one so that an adjustment space 12 required for adjustment of a laser diode 6 is ensured between each fitting portion and fitted portion. This allows the LD holder 10 to be fixed temporarily to the side wall surface 1a of the slide base 1 with the laser diode 6 being adjustable freely, resulting in an improvement in the assembling workability such as chucking of the holder by the adjusting jig and spreading of adhesive.

Abstract: An apparatus for modulating an incident beam includes a body that is non-transmissive and rotatable about an axis perpendicular to a surface of the body. The body has a first set of features including transmissive features with respect to the incident beam along a first radial path at a first radial distance from the axis and a second set of features including data storage features along a second radial path at a second radial distance from the axis. The apparatus also includes a reference sensor disposed over a first position along the second radial path. In the apparatus. the radial distances are different and the numbers of transmissive features and data storage features are relatively prime. When the body is rotating, the first set of features modulate the incident beam and the reference sensor generates a reference signal based on the data storage features traversing the first position.

Abstract: Ferroelectric media includes a media surface that is scannable by a contact. The contact provides a read signal. A polarization pattern is written in first regions of the media surface. The polarization pattern represents position data. The first regions are selectively exposed to an energy source. The exposing provides an imprint to the polarization pattern that prevents subsequent erasure by the read signal.

Abstract: An optical disk reproducing device includes: a semiconductor laser for sequentially emitting singular peak light and singular slope light as laser light when supplied with a driving pulse formed in a form of a pulse and formed of a predetermined singular voltage; an objective lens for condensing the laser light onto a recording layer disposed in an optical disk, and converting an angle of divergence of return light returned from the recording layer; a detection signal generating section configured to detect respective light intensities in each of wavelength bands in the return light, and respectively generate a plurality of detection signals according to the respective light intensities; and a reproduction processing section configured to reproduce information recorded on the optical disk on a basis of the plurality of detection signals.

Abstract: An optical recording and reproducing apparatus is provided for recording standing wave information on an optical recording medium and reproducing standing wave information from an optical recording medium. The optical recording and reproducing apparatus includes an optical head configured to separate a laser beam emitted from a light source (1) into three beams and emit, using an objective lens (7), two beams A and B of the three separate beams into an optical disk (8) having a reflecting surface (10) from the same side of the optical disk (8) so that a focal position SF of the one laser beam A reaching the reflecting surface is the same as a focal position of the other laser beam B after returning from the reflecting surface.

Abstract: An optical pickup includes a first source which emits a first beam with a first wavelength; a second source which emits a second beam with a wavelength shorter than the first wavelength; a first collimates lens which collimates the first beam; a second collimate lens which collimates the second beam; a first objective lens which converges the first collimated beam onto an optical disc; and a second objective lens which converges the second collimated beam onto the disc. The first and second objective lenses are arranged in the disc radial direction. The second objective lens is arranged closer to the side of the disc outer circumference than the first objective lens. The first collimate lens is arranged on the right-hand side when the second objective lens is viewed from the first objective lens. The second collimate lens is arranged on the left-hand side when the first objective lens is viewed from the second objective lens.

Abstract: An objective lens for use in an optical pickup apparatus, comprises an objective lens satisfying the following expression: 0.01?|?SA3obj/??|<0.1 (?rms/nm), where ?SA3obj/?? represents the wavelength dependency of the 3rd order spherical aberration of the objective lens when the oscillation wavelength is fluctuated between ±2 nm.

Abstract: An optical pickup apparatus, comprising: a light source to emit a light flux; a light converging system including an objective lens to converge the light flux emitted from said light source onto an optical information recording medium; a first diffraction element placed within an optical path up to the optical information recording medium; a light flux splitting element that is placed within the optical path from said light source up to the optical information recording medium and that splits an incident light flux emitted by the light source; a monitor element that receives a light flux split by said light flux splitting element and outputs a signal according to a received light amount; a second diffraction element placed between said light flux splitting element and said monitor element; and a control section that controls the drive of said light source according to the signal from said monitor element.

Abstract: The present invention provides an optical pickup apparatus including: a first light source; a second light source; and a light-converging optical system including a coupling lens and an objective lens. The coupling lens includes a first diffractive structure. The optical pickup apparatus satisfies a predetermined condition according to the chromatic aberration, focal length, and dispersion of the material.

Abstract: An optical pickup apparatus for recording and/or reproducing information for an optical information recording medium, comprising a light converging optical system including a coupling lens and an objective lens, wherein a first diffraction structure is installed on the objective lens, and a second diffraction structure is arranged on the coupling lens, whereby the spherical aberration and chromatic aberration caused by the difference in the thickness of the protective layer are corrected in the light converging optical system as a whole.

Abstract: A semiconductor laser driving device is provided with a high frequency superimposing circuit (3) for superimposing a frequency current onto a laser driving current (6) of a semiconductor laser (1) provided in an optical head device; and a high frequency superimposition control circuit (5) which controls the frequency of the high frequency current corresponding to the temperature of the semiconductor laser (1).