Abstract: An apparatus, system, and method are disclosed for a data storage apparatus with a secondary optical memory. The data storage apparatus includes a data storage cartridge, a primary data storage medium in the data storage cartridge, and a secondary optical storage medium attached to the data storage cartridge. The data storage apparatus, in one embodiment, includes a beam splitter attached to the data storage cartridge. The beam splitter may be positioned at approximately a 45 degree angle in relation to a data storage surface of the secondary optical storage medium.

Abstract: An optical pickup unit is disclosed that comprises a first light-emitting element capable of emitting first-wavelength light; a second light-emitting element capable of emitting second-wavelength light whose wavelength is different from that of the first-wavelength light; a polarizing mirror transmitting or reflecting the first-wavelength light and reflecting the second-wavelength light; a first objective lens converging the first-wavelength light on a first medium; and a second objective lens converging the first-wavelength light or the second-wavelength light on a second medium.

Abstract: An optical rotating plate has an optical rotating material layer. A phase plate is provided on a first surface side of the optical rotating plate and has at least one birefringent material layer. The first surface side is disposed toward an emitting side of an optical path, thereby giving different phase differences to a first linearly polarized light group containing at least a linearly polarized light having a first wavelength and a second linearly polarized light group containing at least a linearly polarized light having a second wavelength which is different from the first wavelength.

Abstract: This invention discloses a micro optical pickup apparatus for providing an incident light to an optical recording medium, receiving a reflected light from the optical recording medium, and thereby accessing data of the optical recording medium.

Abstract: An optical pickup including a light source, two light focus devices, a light reception device, a polarization selective light path splitting device, a polarization switching device, a first diffraction element including a periodic structure including two kinds of sub-wavelength convexo-concave structures while the two kinds of sub-wavelength convexo-concave structures alternately arranged at right angles to each other, and the filling factors of the two kinds of sub-wavelength convexo-concave structures are determined to substantially equalize effective refractive indices of the two kinds of sub-wavelength convexo-concave structures with regard to the polarization direction of the outgoing light beam, and the second diffraction element having a structure similar to that of the first diffraction element except that the filling factors are determined to substantially equalize effective refractive indices of the two kinds of sub-wavelength convexo-concave structures with regard to a polarization direction perpen

Abstract: An optical pickup apparatus has a semiconductor laser source which emits a laser beam in a wavelength band of 405 nm having an elliptic light intensity distribution; a beam shaping element which shapes the light intensity distribution of the laser beam; a polarizing beam splitter having a polarized light separation film in contact with the air and reflecting the laser beam shaped by the beam shaping element on the polarized light separation film; and an objective lens which focuses the laser beam reflected on the polarized light separation film onto an optical information recording medium.

Abstract: An optical head and an apparatus using the optical head are shown. The optical head includes a light-emitting element, a first polarized light diverging element for transmitting the light beam of a first polarization direction and reflecting the light beam of a second polarization direction orthogonal to the first polarization direction, a second polarized light diverging element for transmitting or reflecting the light beam of the first polarization direction, a converging element for converging the light beam on an information recording medium, a reflection element for reflecting a first reflected light beam reflected on the information recording medium and reflected on or transmitted through the second polarized light diverging element, and a detection element for detecting a second reflected light beam reflected on the reflection element and transmitted through or reflected on the second polarized light diverging element.

Abstract: An information reproducing apparatus has a light source for generating linearly polarized light, a medium having linear marks disposed in overlapping relation to one another, and an optical head disposed between the light source and the medium and having a fine aperture. A polarized light control portion in the light source controls the linearly polarized light to pass through the fine aperture of the optical head to generate near-field light having a preselected polarization direction and to irradiate the linear marks of the medium with the near-field light so that the preselected polarization direction of the near-field light is orthogonal to a longitudinal axis of each of the linear marks. A detector detects light scattered by the linear mark irradiated with the near-field light.

Abstract: An optical pickup apparatus capable of irradiating an optical recording medium having a plurality of recording layers on which a signal is recorded with laser light includes a light source emitting the laser light, a light-concentrating element concentrating the laser light emitted from the light source on the optical recording medium, a phase difference element having a region divided into at least two regions which the laser light reflected by the optical recording medium enters and producing a phase difference between first light and second light reflected by a non-target layer which is not a target of recording or reproduction of the signal out of the plurality of recording layers and entering the at least two regions such that the first and the second light weaken each other, and a photodetector receiving the laser light emitted from the phase difference element.

Abstract: There is provided an information processing device which is capable of suppressing generation of stray light at the time of recording and reproduction of information, thus enabling quality information recording and reproduction. The information processing device includes: a radiation light source 2; and a converging section for converging rays emitted from the light source toward an information recording medium having a photosensitive layer 11b, wherein the converging section splits the rays into first and second rays 3? and 3 respectively traveling through first and second spaces as divided by a plane at least containing a point optical axis L, and converges the first and second rays 3? and 3 onto first and second points 12? and 12 in the information recording medium 11, the photosensitive layer 11b being interposed between the first and second points 12? and 12.

Abstract: To reduce energy loss on an optical path and improve efficiency of using light volume of light source. A light beam in a P polarized state is emitted from a semiconductor laser 11, and simultaneously a first and second active ?/2 plates 1411 and 1412 are provided in a light path separation/composition unit 14. These first and second active ?/2 plates 1411 and 1412 are for example made of a liquid crystal panel, functions as a ?/2 plate in a turned-off state, and simply functions as a transmission film in a turned-on state. These turned-off and turned-on states are switched over in accordance with types of optical disc, and the optical beam with its polarized state controlled is separated with a third PBS 143. As a result, the light beam is irradiated onto the optical disc DK through a first objective lens 161 in the turned-off state of these first and second active ?/2 plates 1411 and 1412 and through a second objective lens 162 in the turned-on state thereof.

Abstract: An optical head apparatus of an optical information recording/reproducing apparatus is provided with a light source. An objective lens focuses an output light emitted by said light source on a disc optical recording medium for which a groove or a pit for tracking is provided. T photo-detector receives a reflected light reflected by said optical recording medium. A polarizing splitter unit splits said output light and said reflected light. A quarter-wave plate disposed between said polarizing splitter section and said objective lens. A birefringence compensating unit reduces a change in an amplitude of a track error signal caused by birefringence in a protective layer of said optical recording medium.

Abstract: An optical pickup apparatus comprising: a first objective lens; and a second objective lens arranged with the first objective lens in a radial direction of an optical disc, the first objective lens being configured to focus laser light for reproduction, which is laser light for reproducing a signal recorded in a signal recording layer of the optical disc, onto the signal recording layer, the second objective lens being configured to focus laser light for recording, which is laser light for recording a signal, onto the signal recording layer.

Abstract: The present invention relates to a beam shaper and to an apparatus for reading from and/or writing to optical storage media using in such a beam shaper. According to the invention, a beam shaper for generating a first shaped light beam from an incoming light beam has a beam shaping element with an optical property that varies spatially over the profile of the incoming light beam.

Abstract: A laminated wave plate having a wider bandwidth at a desired retardation is provided. A laminated wave plate 1 includes a first wave plate 2 and a second wave plate 3 that are laminated each other so that respective optical axes of the first wave plate and the second wave plate are intersected each other at an angle of 51.5 degrees when the first wave plate has a retardation ?1 of 360 degrees and an in-plane azimuth of ?8 degrees, while the second wave plate has a retardation ?2 and an in-plane azimuth of 43.5 degrees. Thus the laminated wave plate 1 functions as a desired retardation ?2 in a wavelength from 600 nm to 800 nm as a whole.

Abstract: An optical pickup includes: a first light source that emits a first linearly polarized light beam; a second light source that emits a second linearly polarized light beam different from the first wavelength; a drive unit configured to selectively drive the light sources; a first light path along which the first light beam travels to an optical disk; a second light path along which the second light beam travels to the optical disk, the first and second light paths intersecting in the middle of the light paths and are combined into a third light path; a light path-combining optical element provided at the intersection of the first and second light paths; a light path-separating optical element provided along the third light path; a phase difference-imparting optical element provided along the third light path; and a light receiving element that receives the first and second light beams reflected off the optical disk.

Abstract: A quarter-wave plate and a polarization beam splitter are used as means for guiding a laser beam to first and second objective lenses. A half of the circularly-polarized laser beam incident to the polarization beam splitter is reflected in the form of an S-polarized light component by the polarization beam splitter and guided to a first objective lens, and the other half is transmitted through the polarization beam splitter in the form of a P-polarized light component and guided to a second objective lens. The whole of light quantity of the laser beam reflected from an optical disk through the first or second objective lens passes substantially through the polarization beam splitter. Therefore, the light quantity of the laser beam guided to a photodetector can be enhanced.

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 optical pickup device according to an aspect of the present invention includes a rotary mechanism which rotates a half-wave plate in mechanical conjunction with drive of first and second collimator lenses. The rotary mechanism locates the half-wave plate at a first rotational position when the first collimator lens is located at a control operation position, and the rotary mechanism locates the half-wave plate at a second rotational position when the second collimator lens is located at the control operation position. When the rotational position of the half-wave plate is switched between the first rotational position and the second rotational position, a polarization direction of a laser beam is changed with respect to the polarization beam splitter to switch an optical path of the laser beam.

Abstract: An optical pickup apparatus includes a first objective lens having a low numerical aperture (NA) suitable for a low density recording medium, a second objective lens having a high NA suitable for a high density recording medium, a first light source that emits short wavelength light which is focused onto an optical recording medium by the first and second objective lenses, a first photodetector that receives a returning reflected light from the optical recording medium, and a first optical path converter for selectively guiding part of the light emitted from the first light source towards the first or the second objective lens, and guiding the reflected light towards the first photodetector.

Abstract: An optical head device may include a polarization conversion element disposed on a common optical path for guiding a first and a second laser beams to a common objective lens for converting the first and the second laser beams to a circularly polarized light from a linearly polarized light, and a ½-wavelength plate disposed on an optical path of the first laser beam from a first laser light source to the common optical path for adjusting a polarization plane direction of the first laser beam. A polarization plane direction of the first laser beam incident on the polarization conversion element from the first laser light source is adjusted by the ½-wavelength plate in a direction so that the linearly polarized light is converted into the circularly polarized light.

Abstract: An interference type optical head and an optical disk device that can easily adjust an optical path length difference of a couple of lights, ensure higher signal amplification effect, and are suitable for reduction in size are provided in order to improve a regeneration signal quality with amplification of signal in the case where reflectivity of each layer must be lowered and relative noise for the signal increases because read speed is high in a multilayer optical disk. In view of essentially improving an S/N ratio of the regeneration signal in high-speed rotation of a multilayer disk, a plurality of interference phases are generated and an optical system for differential calculation has been reduced in size with an angular selective polarization conversion element in the optical disk device for amplifying the signal with interference of the light not radiated to the disk with the reflected light from the disk.

Abstract: In an optical scanning device (10) capable of scanning an information plane of an optical record carrier (5) of different types such as BD, DVD and CD, the diameter of the radiation spot on the detector (7) is dependent on the numerical aperture of the objective system (4) that is used for scanning the record carrier An optimal design of the optical detection system for scanning a BD, result in a small radiation spot for the other types such as DVD and CD.

Abstract: An optical pickup includes a laser light source, an objective lens which focuses light emitted from the laser light source on an optical information storing medium, an optical path changer which changes a proceeding path of the light emitted from the laser light source, a polarization changer which changes the polarization of an incident light to make the polarization of light reflected by the optical information storing medium and reentering the laser light source different from that of the light emitted from the laser light source, so that noise generated due to interference by the light reflected by the optical information storing medium and reentering the laser light source is reduced, and a photodetector which receives incident light reflected by the optical information storing medium and sequentially passing through the objective lens and the optical path changer and detects an information signal and/or an error signal.

Abstract: According to an embodiment of the optical head unit includes two or more light sources, an objective lens which condenses the light beam having the predetermined wavelength output from each of the light sources to a recording layer of a recording medium, and captures a light beam reflected on the recording layer, a polarization control element arranged between the light sources and the objective lens, to optimize directions of polarization of the light beam having the predetermined wavelength output from the light source and the light beam reflected on the recording layer, in accordance with the wavelength thereof, on the basis of a voltage to be applied, a photodetector which receives the reflected light beam captured by the objective lens and outputs a predetermined signal, and a polarization controller which varies the direction of polarization set by the polarization control element, in accordance with the output of the photodetector, the fluctuations of the signals recorded and/or reproduced in each wave

Abstract: An optical pickup device is constituted to enable stable recording or reproduction on/from a recording medium.

Abstract: When an optical recording medium having a plurality of data layers is being read from and/or written to, the input beam experiences an aberration, inter alia in the top layers of the data layers. In order, nevertheless, to achieve a high data density, a device for correcting the spherical aberration is located in the beam path of the input beam. In the case of the use of an optical diode in which the input beam and the reflected beam have directions of polarization perpendicular to one another, such a device is expensive to implement and associated with a reduced optical efficiency. It is an object of the invention to propose an apparatus for reading from and/or writing to optical recording media, in the case of which a high optical efficiency and balancing of the spherical aberration are achieved with low outlay.

Abstract: The optical miniaturized module includes a semiconductor laser for irradiating an optical disk with laser light, a diffraction grating for forming a main beam and two sub beams from the laser light, a polarization hologram for dividing reflected light from the optical disk, and a photodetector for detecting the reflected light. The polarization hologram includes a first parting line defined in a direction optically corresponding to a radial direction as the optical disk rotates. A main beam M incident area is divided with a boundary defined by the first parting line. A sub beam A incident area and a sub beam B incident area are each arranged avoiding the first parting line.

Abstract: A fixing structure for an optical element includes a first element face of the optical element, a second element face of the optical element which is orthogonal to the first element face, a first positioning plane of a fixed member which abuts with the first element face of the optical element and is fixed on the first element face with an adhesive, and a second positioning plane of the fixed member which is orthogonal to the first positioning plane and abuts with the second element face of the optical element. The second positioning plane is defined by a small projecting part which protrudes from the fixed member perpendicularly with respect to the first positioning plane to abut with the second element face. The fixing structure for an optical element is preferably applied to an optical head device.

Abstract: An optical pickup device for resolving problems with deterioration in the RF signal due to crosstalk from the preformatted structures in optical disks which provide address information, especially the Land Pre-Pit signal in optical disks such as DVD-R and DVD-RW disks with a LPP (Land Pre-Pit) structure. When the ratio of electric amplitude (Etan/Erad) of the incident light onto the disk, where Etan and Erad shows the electric amplitude of the foregoing light in the tangential and radial direction of the disk, is set to ? then the optical pickup device is set so that 0.7<? (electrical amplitude ratio)<0.8.

Abstract: An optical pick-up including a fold mirror having an achromatic quarter-wave plate coating is provided. To allow the thin film coating to efficiently provide the quarter-wave retardation, the optical pick-up is configured such that the polarization of light incident on the fold mirror is at a predetermined angle. According to one embodiment, the predetermined angle is provided by rotating the light sources. According to another embodiment, the predetermined angle is provided by rotating a plane containing the light sources and the beam combiners. In each embodiment, the beam combiners and the fold mirror are arranged along the same axis to further improve efficiency.

Abstract: An optical pickup device compatible with two types of optical recording media in accordance with the present invention includes: a first light source emitting a first laser beam with a first wavelength; a second light source emitting a second laser beam with a second wavelength greater than the first wavelength; an objective lens with parameters according with the first wavelength and adapted to focus the first and second laser beams on the at least two types of optical recording media; a collimating lens for collimating an incident beam of light and transmitting the collimated light beam to the objective lens; an optical path synthesizer/separator for receiving the first and second laser beams and transmitting the first and second laser beams to the collimating lens; and a compensator for correcting the second laser beams and transmitting the corrected second laser beams to the optical path synthesizer/separator.

Abstract: A polarized-light splitting device includes a transmissive base member having a base portion and pattern of ridges on the base portion, and a non-transmissive layer on the ridges, wherein the non-transmissive layer includes a light reflecting portion, and a light absorbing portion.

Abstract: Provided is an optical disc apparatus including an interference-type optical disk signal detection system, which allows an optical path difference between two kinds of light to be controlled easily, which has a high signal amplification effect, and which is suitable for miniaturization of an optical system. An interference-type optical system is integrally formed to stabilize an optical path difference between signal light and reference light. At the same time, means for controlling an optical path length of the reference light is attached to a reference mirror, and thereby controls signal amplitude so as to be constantly set the maximum in response to a change in the optical path length with time due to a variation in the thickness of a cover layer of an optical disk, a temperature and the like. Moreover, the optical system is miniaturized by using a Twyman-Green type interference optical system.

Abstract: The amount of reflected light from an adjacent layer in a multilayer optical disc is reduced by means of a combination of half-wave plates having different optical axes and a flat mirror. The polarization direction of the reflected light from a target layer is changed without changing the polarization direction of reflected light from the adjacent layer so as to detect a signal from the target layer alone. Because no stray light is introduced into the tracking error signal or focus signal, the laser light irradiated position can be controlled with high accuracy. This makes it possible to accurately determine the laser irradiated position during reading and writing, thereby enhancing signal quality. Because no reflected light from the adjacent layer is introduced into the data signal, a data signal with reduced error can be obtained.

Abstract: An optical pickup in an optical disk reproducing device is operable to switch operations between a low-power operation mode and a high-power operation mode, and includes a liquid crystal element and a polarization beam splitter, which together attenuate, only in the low-power operation mode, a laser beam emitted by a laser diode onto an optical disk. The liquid crystal element is turned ON only in the low-power operation mode to serve as a polarization rotating element. Working with the polarization beam splitter, the polarization rotating element attenuates a polarized component of the incident light on the optical disk.

Abstract: An optical pickup is configured to emit a light beam to an optical disk having a plurality of recording layers and is configured to receive a reflection light beam obtained when the emitted light beam is reflected at a recording layer of the optical disk. The optical pickup includes an objective lens configured to focus the light beam emitted from a light source at a focused recording layer of the optical disk and receive the reflection light beam; a focusing lens configured to focus the reflection light beam received by the objective lens; and a stray-light removing element including the boundary surface and being configured to remove stray light from the reflection light beam by reflecting only the stray light included in the reflection light beam reflected at an unfocused recording layer at the boundary surface.

Abstract: An optical pickup apparatus is provided with a light source device to emit selectively an ordinary polarized light ray and an extraordinary polarized light ray by controlling a polarization condition of a light flux having a wavelength of ?1; and a light converging optical system. An objective lens has a phase structure made of a doubly refracting medium in which an ordinary ray refractive index no for the ordinary polarized light ray is different from an extraordinary ray refractive index ne (ne?no) for the extraordinary polarized light ray so that the phase structure has a function for not changing a transmitted wavefront of an incident light ray being one of the ordinary polarized light ray and the extraordinary polarized light ray and for changing a transmitted wavefront of an incident light ray being the other one of the ordinary polarized light ray and the extraordinary polarized light ray.

Abstract: An optical pickup for writing information to and/or for reading information from an optical disc having at least two recording layers (dual layer) provided with first and second recording layers can prevent layer crosstalk resulting from disturbing a signal reproduced from the first recording layer by a reflected light beam reflected from the second recording layer during a writing operation for writing information to the first recording layer or a reading operation for reading information from the fist recording layer. An orthogonal polarization region forming component forms an orthogonal polarization region, in which respective directions of polarization of a first light beam focused on and reflected by a first recording layer of an optical disc and a second light beam reflected by a second recording layer of the optical disc are perpendicular to each other, in a region, in which the first and the second light beam overlap each other, on a light-receiving surface of a detector.

Abstract: The present invention is for providing optical head apparatus that can control scatter occurring at locations along the length of the optical path, when laser beam is transmitted through prism constituting the No. 1 prism structural member and the No. 2 prism structural member joined through partially reflecting face. Optical head apparatus 1 performs information recording, information regeneration on an optical recording medium, e.g. DVD; laser beam emitted from laser beam-emitting element is transmitted through a prism. The prism has the structure wherein triangular the No. 1 prism structural member and similarly a triangular No. 2 prism structural member are joined through partially reflecting face.

Abstract: Provided is a focus and tracking control method for an optical pick-up apparatus which is used for recording and reproduction of a small-sized optical disc and which can carry out stable focus control and stable tracking control. A focus control method for an optical pick-up apparatus comprising a light source, an objective lens, a light receiving means having divided four light receiving zones and a polarizing means having divided for lattice zones, characterized in that when the reflected light beam is incident upon the four light receiving zones by way of the four lattice zones, focus control is carried out in accordance with a difference signal between the groups, in the radial direction, of the four light receiving zones which are divided into two groups in the radial direction by the division line in parallel with the tangential direction, respectively through the four lattice zones which are divided into two groups in the tangential direction by a division line in parallel with the radial direction.

Abstract: An optical pickup apparatus and an optical recording/reproducing apparatus employing the optical pickup apparatus, which can be adaptive for multiple types of optical discs different in the layout conditions such as recording density, etc., are provided. The optical pickup includes an optical pickup for accessing at least first and second optical recording mediums, the pickup comprising a first light source generating a first light beam of a first wavelength; a second light source generating a second light beam of a second wavelength different from the first wavelength; an optical section transmitting the first and second light beams; and an aperture number controller including a wave selecting member for selecting between the first and second light beams of different wavelengths so as to impinge a light beam with an appropriate aperture number to selectively access one of the at least first and second optical recording mediums.

Abstract: An optical pickup having a simple structure and that is capable of recording using a plurality of wavelengths is provided, comprising a primary laser light source for emitting a primary laser light having a first wavelength and that is of sufficient power for recording, an integrated device further comprising a secondary laser light source for emitting a secondary laser light having a second wavelength that is longer than the first wavelength and that is of sufficient power for recording as well as light receiving elements for receiving the light of the primary and secondary laser lights, and a polarized light beam splitter having polarization selectivity in respect of the secondary laser light.

Abstract: The present invention is directed to an optical head adapted for performing recording or reproduction of information signals with respect to an optical disc (102), which controls light coupling efficiency with respect to light beams irradiated onto the optical disc (102) by light coupling efficiency adjustable element such as a liquid crystal element (214), etc. in accordance with type of the optical disc (102), recording surface of multi-layer optical disc and/or operation mode to change power of light beams irradiated onto the optical disc (102) to a large extent without excessively increasing change quantity of output power of a semiconductor laser element (212). A beam splitter (218) divides incident light beams of P-polarized light at a predetermined ratio to allow the light beams thus obtained to be incident on a light detector (219) for disc surface power monitor.

Abstract: A hologram recording medium is a hologram recording medium which is irradiated with light for recording information therein or reproducing information therefrom. The hologram recording medium has a recording layer made of a photo-sensitive material capable of preserving an optical interference pattern, a reflective layer disposed on one side of the recording layer opposite to the side on which an light beam impinges, and a quarter wavelength plate interposed between the recording layer and the reflective layer.

Abstract: A optical scanning device (1) for scanning an information layer (2) with a radiation beam (25) in a writing mode and a reading mode comprises a radiation source (7) for emitting the beam and an objective lens (10) for converging the beam so as to form a scanning spot (19) in the information layer. The device also includes a scanning spot power switch (20) for switching the size of the cross-section of the beam between a first size at the writing mode and a second, larger size at the reading mode so as to switch the rim intensity of the beam between a first intensity level (Irim,writing) at the writing mode and a second, higher intensity level (Irim,reading) at the reading mode, thereby switching the light power of the scanning spot between a first power level (Pwriting) at the writing mode and a second, lower power level (Preading) at the reading mode.

Abstract: The present invention relates to an optical device which includes a first laser diode, a beam splitter, a first objective lens, a photo-detector, a second laser diode, a wedged plate beam splitter, a second objective lens and a collimator. The present invention deploys two independent transmitting paths. The retrieving paths share the beam splitter and the photo-detector commonly at the returning route.

Abstract: An optical head for recording or reproducing a signal with respect to an optical recording medium, which includes an optical element disposed between a light source and an optical recording medium. The optical element has an optically active polymer film in which an optical rotation property changes with respect to an applied voltage, a pair of conductive transparent thin films for applying a voltage to the optically active polymer film, and a transmittance polarization anisotropic part having a different transmittance with respect to a polarization direction, which is disposed on one of the conductive transparent thin films. By changing the applied voltage to the optically active polymer film, a light quantity of a linearly polarized light transmitted through the optical element can be changed substantially instantaneously. Therefore, the power of light reaching the optical recording medium can be switched substantially instantaneously at the time when switched between recording and reproduction.

Abstract: An optical pick-up apparatus and a semiconductor laser apparatus which can suppress reduction of optical utilization efficiency for the laser light emitted from the semiconductor laser element. When a laser light which is emitted from a laser element for DVD and whose polarization direction is perpendicular to a direction of a groove of the polarization grating is incident on the polarization grating, the polarization grating does not diffract the laser light and transmits the laser light as zero-order diffraction light. Consequently, all of the laser light emitted from the laser element for DVD can be used for reading information signal of DVD and detecting FES and TES. This enables reduction of optical utilization efficiency arising by diffracting action of a grating used for detecting TES of CD in a conventional optical pick-up apparatus to be suppressed.

Abstract: An optical scanning device for scanning an optical record carrier includes a radiation source and a beam splitter arranged to pass a first portion of the source beam to the record carrier, and a second portion to an intensity sensor. A signal detector is arranged in the path of the beam reflected by the record carrier. False radiation reflected by the signal detector can be prevented from reaching the intensity sensor by tilting the signal detector. A polarization filter may be arranged in front of the intensity sensor to prevent false radiation reflected by the radiation source and by the signal detector from reaching the intensity sensor.