Abstract: Disclosed are a camera and an image display apparatus including the same. The camera according to an embodiment of the present invention comprises: a first optical structure configured to refract and reflect a first input beam to output a second beam with a width smaller than a width of the first input beam; and a second optical structure configured to refract and reflect the second beam from the first optical structure to output a third beam with a width greater than the width of the second beam, wherein the first optical structure comprises a first reflection surface configured to reflect the first input beam, and wherein a first angle between the first reflection surface and the second beam and a second angle between an orthogonal surface orthogonal to the first input beam and the first reflection surface are each greater than 0° and smaller than 45°. Accordingly, a thickness of the camera may be reduced.

Abstract: An inspection apparatus, including: a measurement optics system configured to scan an object to be inspected with measuring light from a light source; a dividing unit, which is arranged at a position conjugate with the object to be inspected, and is configured to divide return light, being the measuring light returning from the object to be inspected, into a plurality of light beams; a photo-receiving unit configured to receive the plurality of light beams obtained by the division; a recording unit configured to record image data of the object to be inspected, which is based on a plurality of intensity signals output by the photo-receiving unit, and a division direction in which the return light is divided, the image data being associated with the division direction; and an analysis unit configured to analyze the image data based on the associated division direction.

Abstract: Provided are an optical pickup device and an optical disk drive including the same. The optical pickup device includes a quarter-wave plate (QWP) that is disposed parallel to an objective lens and a reflection mirror that reflects a beam back onto the QWP after the beam passed through the QWP. The optical pickup device also includes a polarization mirror that is disposed between the objective lens and the QWP, and which reflects the beam which is generated from a light source onto the QWP, and allows the beam reflected by the reflection mirror to pass through to the objective lens.

Abstract: A system and method for providing direct read after write functionality in an optical data storage device include an optical head having a first coherent light source modulated at higher power during writing of data to the optical medium and a second coherent light source operating in a continuous wave mode at lower power while the first coherent light source is writing data. Optic components combine light from the first and second light sources and focus light from the first coherent light source to a first spot of a selected track on the optical medium and focus light from the second coherent light source to a second spot on the selected track downstream from the first spot relative to movement direction of the optical medium to read and verify the data directly after writing during the write process rather than in a separate verification process.

Abstract: An optical pickup apparatus includes: a laser light source to emit a laser beam; an object lens to irradiate an optical recording medium with the laser beam; a photodetector to receive a reflected light of the laser beam reflected by the optical recording medium; a semitransparent mirror interposed on an optical path between the laser light source and the object lens, to reflect the laser beam in a direction of the object lens and transmit it in a direction of the photodetector; and an astigmatism adding member interposed on an optical path between the semitransparent mirror and the photodetector, to add astigmatism to the reflected light, wherein the astigmatism adding member includes control film having first transmittance for polarization component in first direction contained in the reflected light is substantially equal to second transmittance for polarization component in second direction perpendicular to the first direction contained in the reflected light.

Abstract: A phase difference layer 12 and a reflection layer 13 are provided. Then, adjustment is performed such that the phase difference layer 12 and the reflection layer 13 impart a predetermined phase difference to light having a particular wavelength bandwidth or plural kinds of light of different wavelengths that enter in an oblique direction relative to the normal direction of the plane of the phase difference layer 12. By virtue of this, the light 16a that goes forward and backward through the phase difference layer 12 and then exits the layer has an ellipticity ? of 0.7 or greater. Thus, in particular, when this wave plate is employed in an optical head device, the function of reflection and the function of a ¼-wave plate are integrated. Thus, stable recording and reproduction of an optical disk are achieved, and size reduction is achieved in the optical head device.

Abstract: A method of manufacturing a thermally-assisted magnetic recording head includes: providing a light source unit including a laser diode; providing a slider having a thermally-assisted magnetic recording head section thereon, the thermally-assisted magnetic recording head section including a magnetic pole, an optical waveguide, and a plasmon generator, the magnetic pole and the optical waveguide both extending toward an air bearing surface, the plasmon generator being located between the magnetic pole and the optical waveguide; driving the laser diode to allow a light beam to be emitted therefrom, the light beam including both a TE polarization component and a TM polarization component; performing an alignment between the light source unit and the thermally-assisted magnetic recording head section, based on a light intensity distribution of the TE polarization component in the light beam which has been emitted from the laser diode and then passed through the optical waveguide; and bonding the light source unit

Abstract: An optical pickup has a first optical system and a second optical system. The optical axis of the first optical system and the optical axis of the second optical system are inclined, for example, 45 degrees with respect to the reference plane, and are parallel to each other. A first objective lens and a second objective lens are arranged substantially side-by-side in a radial direction, and the center position of the second objective lens is slightly displaced from the reference plane in a tangential direction. The first optical system and the second optical system each have a flat-shaped beam splitter; this is used to produce astigmatism for acquiring a focus error signal by the astigmatic method.

Abstract: An optical head for recording or reproducing a signal on or from an optical recording medium including a light source, an objective lens for condensing light emitted from the light source to the optical recording medium, and a light-separating device arranged between the light source and the objective lens in order to separate the light reflected from the optical recording medium from the light emitted from the light source. The light-separating device includes a first glass, a multilayer film formed on the first glass, and an adhesive layer arranged on the multilayer film in order to bond a second glass onto the multilayer film. The majority of the light emitted from the light source enters into the light-separating device through the first glass and is reflected by the multilayer film.

Abstract: An optical pickup apparatus comprising: a collimating lens configured to convert laser light emitted from a laser diode, from diffused light into parallel light; an objective lens; and a prism configured to guide the laser light emitted from the collimating lens to the objective lens, the prism including: a first face that the laser light emitted from the collimating lens enters; a second face that reflects the laser light entering the first face; and a third face that reflects the laser light reflected from the second face in a direction of the second face, and emits the laser light reflected again from the second face in a direction of the objective lens.

Abstract: An optical pickup device includes a plurality of laser light sources emitting laser beams of different oscillation wavelengths, and a plurality of objective lenses on which the laser beams in the form of diverging beams emitted by the plurality of laser light sources are incident, and which directly focus the laser beams onto a recording surface of an optical disc. A rising mirror reflects a laser beam in the form of a diverging beam emitted by a laser light source of a predetermined oscillation wavelength among the plurality of laser light sources so as to lead the laser beam to one of the plurality of objective lenses, and transmits the laser beam in the form of a diverging beam emitted by the other laser light source. As the rising mirror transmits the laser beam in the form of the diverging beam emitted by said other laser light source, astigmatism is generated so as to correct existing astigmatism of the laser beam emitted by said other laser light source.

Abstract: An optical pickup device has a DVD/CD laser diode for emitting a DVD/CD laser beam as linear polarized light, and a BD laser diode for emitting a BD laser beam. The optical pickup device has a dichroic mirror that regularly reflects a part of the DVD/CD laser beam, transmits a part of the DVD/CD laser beam, and transmits return light of the BD laser beam. The dichroic mirror is formed so that a product of reflectance of outward light of the DVD/CD laser beam and transmittance of return light of the DVD/CD laser beam becomes 20% or more to 25% or less. A light receiving element receives the return light of the DVD/CD laser beam transmitted through the dichroic mirror or the return light of the BD laser beam transmitted through the dichroic mirror.

Abstract: A laminated half-wave plate includes: first and second wave plates having optical axes intersecting each other, wherein when phase differences of the first and second wave plates with respect to a wavelength ? are represented by ?1 and ?2, in-plane bearing angles formed by a polarization plane of a linearly-polarized beam incident on the laminated half-wave plate and the optical axes of the first and second wave plates are represented by ?1 and ?2, an angle formed by the polarization directions of the linearly-polarized beams incident on and emitted from the laminated half-wave plate is represented by ?, and an optical axis adjustment amount is represented by a, the following expressions are satisfied: ?1=180°+n×360°; ?2=180°+n×360° (where n in ?1 and ?2 is a non-negative integer); ?1=?/4+a; and ?2=3?/4?a.

Abstract: Provided are an optical pick up and an optical component used for the optical pickup which are capable of preventing or restraining occurrence of deviation and unbalance which are caused by assembly errors during manufacturing of optical components, a temperature variation or the like. The optical pickup comprises a laser, a polarization changeover element for changing over a direction of polarization of an optical beam emitted from the laser, a beam splitting element for splitting the laser beam into a plurality of optical paths in accordance with a direction of a polarization, a plurality of objective lenses for focusing laser beams onto a recording layer of the optical disc, a rise-up mirror, and a plurality of coupling lenses arranged respectively intermediate of the plurality of optical paths led to the plurality of objective lenses.

Abstract: An optical device for holographic recording or reading is provided and includes: a light emission unit that emits light to be irradiated on an optical recording medium, the light being recording or reading light; a first prism unit that moves in accordance with a moving speed of the optical recording medium and refracts the light to move the light irradiated on the optical recording medium over a distance in a moving direction of the optical recording medium so that the light is irradiated on substantially the same position on the optical recording medium for a period of time; and a second prism unit that moves in accordance with the moving speed of the first prism unit to compensate for an optical path length of the light.

Abstract: A thermally assisted magnetic head has a slider having a medium-facing surface, and a light source unit having a light source support substrate, and a light source disposed on the light source support substrate; the slider has a slider substrate and a magnetic head portion disposed on a side surface of the slider substrate; the magnetic head portion has a magnetic recording element for generating a magnetic field, first and second waveguides, for receiving light through an end face and guiding the light to the medium-facing surface, and a near-field light generator disposed on an end face; the light source support substrate is fixed to a surface of the slider substrate so that light emitted from the light source can enter the end face of the first waveguide.

Abstract: An optical-pickup apparatus comprising: a polarization beam splitter fixed to a base, which includes a first prism that laser light emitted from a laser diode enters, a second prism that return light of the laser light reflected from a signal recording layer of an optical disc enters, and a control film that is formed on either one of opposed surfaces of the first and second prisms so that the laser light and the return light are selectively passed through or reflected from the control film, the opposed surfaces being opposed to each other; and first and second positioning pins provided on the base to position the polarization beam splitter, the polarization beam splitter being fixed to the base in a state where the opposed surface of at least one of the first and second prisms is made in contact with at least one of the first and second positioning pins.

Abstract: A multiple wavelength-adaptive optical pickup according to the present invention enables to obtain stable signals by suppressing displacement of optical intensity distribution at a light receiving section. When an incident angle of a central beam of a zero-dimensional beam of a beam reflected at an optical disc into a half mirror is taken as ?, if variation in transmittance of the mirror become a maximum with respect to change in the incident angle from ? to a plus side in any one of the wavelengths corresponding to the respective optical discs, a ?1 dimensional beam generated on the minus side with respect to the zero-dimensional beam is received by the light receiving section, and if the variation in the transmittance of the mirror become the maximum with respect to change in the incident angle from ? to the minus side, a +1 dimensional beam generated on the plus side with respect to the zero-dimensional beam is received by the light receiving section.

Abstract: An optical head for recording or reproducing a signal on or from an optical recording medium including a light source, an objective lens for condensing light emitted from the light source to the optical recording medium, and a light-separating device arranged between the light source and the objective lens in order to separate the light reflected from the optical recording medium from the light emitted from the light source. The light-separating device includes a first glass, a multilayer film formed on the first glass, and an adhesive layer arranged on the multilayer film in order to bond a second glass onto the multilayer film. The majority of the light emitted from the light source enters into the light-separating device through the first glass and is reflected by the multilayer film.

Abstract: An optical pickup device includes: a light source; a collimator lens for converting a light beam emitted from the light source into parallel light; an objective lens for converging the light beam to the optical disc; an extending portion in which a light flux transversal width as the width of the parallel direction with respect to the information recording face of the optical disc of the light beam converted into the parallel light by the collimator lens is extended until a final light flux diameter as the diameter of the light beam at an incident time to the objective lens; and a prism in which a light flux longitudinal width as the width of a direction perpendicular to the information recording face of the optical disc of the extended light beam is extended until the final light flux diameter, and the light beam is emitted to the objective lens.

Abstract: An optical integrated unit of the present invention includes: a semiconductor laser that is a light source; at least one light receiving element; a light dividing section which divides outgoing light from the semiconductor laser and returning light from an optical disc, and reflects the returning light so as to guide it to the light receiving element; and a support substrate, and a second support substrate is concave, the light dividing section includes at least three prisms, the prisms on both sides of the light dividing section are respectively adhered to two protrusions of the concave second support substrate, and the light receiving element is adhered to the light dividing section via a cover glass. With this, it is possible to solve a problem of a conventional technology, that is, such a problem that the light receiving element cannot be adjusted highly accurately because of the thickness errors of the support substrate and the relay substrate.

Abstract: The present invention can simplify the configuration of a polarization adjustment plate. According to the present invention, the crystal axis of the polarization adjustment wavelength plate 32 is so arranged as to be turned up from the X-Y plane being an orthogonal plane with respect to the optical axis 40a, and the wavelength dependence which the crystal material is originally provided with is largely expressed, and further the thickness “ta” with respect to the optical axis 40a is set up such that the phase difference ? to be brought about at the beam center becomes low from 360°+180°=540° being a desired design value to irradiate the optical beam as the P-polarization by a predetermined difference value or 60°.

Abstract: There is provided an inexpensive optical pickup device that is capable of accurately detecting light quantities of output laser beams on occasion of at least either of reproduction and recording on an information recording medium. A beam from a first light source 1 which beam does not pass through a wavelength selection film 6 of a light separation element 7 is reflected by a first reflection film 10 in a direction to an optical monitor 5. A beam from a second light source 2 which beam does not pass through the wavelength selection film 6 of the light separation element 7 is reflected by a second reflection film 11 in a direction to the optical monitor 5.

Abstract: A near field light generating device generating near field light from incident light by using a solid immersion mirror and a heat assisted magnetic recording head with the same are provided. The near field light generating device includes a light source; a waveguide core which transmits light; and a solid immersion mirror, which generates near field light, including an upper transmission surface through which light from the waveguide core is transmitted into the solid immersion mirror, a lower reflection surface, opposite the upper transmission surface, which reflections light incident thereon, lateral reflection surfaces, facing each other at sides of the solid immersion mirror, which reflect light incident thereon, and a lower transmission region disposed at a center of the lower reflection surface. Light reflected from the lateral reflection surfaces forms a light spot on the lower transmission region.

Abstract: An optical element for use in an optical pickup apparatus includes a substrate made of resin; an antireflection layer coating the substrate and having a low refractive index layer and a high refractive index layer, wherein the resin includes a polymer with an alicyclic structure, the low refractive index layer is formed of a material selected from the group consisting of silicon oxide; aluminum fluoride; yttrium fluoride; magnesium fluoride; a mixture of silicon oxide and aluminum oxide; and a mixture thereof, the high refractive index layer is formed of a material selected from the group consisting of scandium oxide; niobium oxide; lanthanum oxide; praseodymium titanate; lanthanum titanate; lanthanum aluminate; yttrium oxide; hafnium oxide; zirconium oxide; tantalum oxide; a mixture of tantalum oxide and titanium; silicon nitride; and a mixture thereof.

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 pickup system includes a first light source emitting first light beams with a first wavelength, a second light source emits second light beams with a second wavelength greater than the first wavelength, a third light source emits third light beams with a third wavelength greater than the second wavelength, a composite prism comprising a first prism facing the first and second light sources, a second prism facing the third light source, and a third prism for receiving the first, second and third light beams from the first and second prisms, the first prism has a surface facing the first and second light sources, the surface defines first and second regions, the second region has an aspherical surface to compensate aberration of the second light beams, a collimating lens and objective lens disposed in a common optical path for transmitting the three light beams from the composite prism.

Abstract: An optical pickup which can remove birefringence due to the non-uniformity of an optical recording medium by using a polarization beam splitter. The optical pickup includes a light source emitting a laser beam, a beam splitter reflecting part of incident light and straight transmitting the remaining light to change a proceeding path of the incident light, an objective lens focusing the incident light passed through the beam splitter to form a light spot on an optical recording medium, a polarization beam splitter arranged on an optical path between the beam splitter and the objective lens for transmitting light having one polarization and reflecting light having a different polarization.

Abstract: An optical pickup head (100) for a high density recording and/or reproducing device compatible with three types of optical recording media. The pickup head includes a first light source (11a) emitting first beams with a first wavelength, a second light source (12a) emitting second beams with a second longer wavelength, a third light source (13a) emitting third beams with a third even longer wavelength, a prism unit (3), a collimating lens (4) located beside the prism unit, and an objective lens (7) for receiving the light beams and transmitting them to the recording media respectively. The prism unit includes a first portion facing the first source and receiving the first beams, a second portion facing the second source and receiving the second beams, a third portion facing the third source and receiving the third beams, and first and second aberration-correcting portions for the second and third beams to pass therethrough.

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

Abstract: It is an object of the invention to provide an aberration correcting mirror which has a small size, power saving, a low voltage, a low price and high precision. In particular, it is an object to provide a practical mirror for correcting a spherical aberration.

Abstract: A compatible optical pickup apparatus and method are provided. The apparatus and method include a first light source for generating and emitting a first light having a predetermined wavelength, a second light source for generating and emitting a second light having a wavelength different from the wavelength of the first light, a beam shaping beam splitter provided in paths of the first and second lights for shaping the first and second lights in order to change a shape of a profile of each of the first and second lights to a circular shape and change the paths of the first and second lights, an objective lens for focusing the first and second lights and forming light spots on an optical recording medium, and a main photodetector for receiving the first and second lights by being reflected from the optical recording medium and passing through the objective lens and the beam shaping beam splitter, and detecting an information signal and an error signal.

Abstract: An optical pickup device has first and second light sources that emit first and second laser beams of different wavelengths, an object lens that concentrates the first and second laser beams on a data recording surface of an optical disk, an optical separator disposed between the first and second light sources and the object lens, and an optical monitor that detects a quantity of light of the second laser beam. The optical separator has a wavelength selecting film that, on one hand, reflects the first laser beam emitted from the first light source toward the object lens and, on the other hand, transmits the second laser beam emitted from the second light source to the object lens, and a reflector that reflects a part of the second laser beam emitted from the second light source toward the optical monitor.

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

Abstract: 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: An optical pickup device and an optical recording and reproducing apparatus are suitable for use with a near-field optical recording and reproducing system.

Abstract: This invention is an optical pickup device having a composite optical element (32) which has a first diffraction grating (45) for splitting a light beam emitted from a light source (31) into zeroth-order light, plus-first-order light and minus-first-order light, a second diffraction grating (46) for diffracting the optical path of a return light beam from an optical disc (2), and a split prism (47) arranged at a position where the minus-first-order light diffracted by the second diffraction grating (46) is incident and adapted for splitting the minus-first-order light into a plurality of light beams. It also has a light receiving unit (35) for acquiring a focusing error signal FE by receiving each return light beam split by the split prism (47) and for acquiring a tracking error signal by receiving return light beams from the optical disc (2) of the plus-first-order light and the minus-first-order light split by the first diffraction grating (45).

Abstract: A light receiving and emitting unit has a plurality of light sources, a light receiving element, a light control unit, and an optical block. The optical block has at least a first and a second member formed of a material having birefringent property, and a third member interposed between the first and the second member and formed of a material having lower refractive index than the first and the second members. The light control unit has a crystal thin plate, a pair of electrodes formed on the surfaces of the crystal thin plate so as to sandwich the crystal thin plate for applying a voltage to the voltage application area, and a first and a second insulating member for sandwiching the crystal thin plate so as to cover the electrodes.

Abstract: An optical head for use in the scanning of a record carrier, the record carrier having data stored on data tracks therein on a plurality of information layers (3, 4) at a plurality of depths within the record carrier. The optical head comprises: a movable optical element (16) arranged in an optical path to act upon a first radiation beam (12) and a second radiation beam (14) to provide the beams with a different displacement perpendicular to the optical path; and a lens system for focusing said first beam (12) at a first focal point (A) on a first information layer (3) of the record carrier and the focusing of the second beam (14) at a second different focal point (B) on a second information layer (4), wherein a spacing, transverse to the data tracks, between said first and second focal points (A, B) is controllable by varying the configuration of the movable optical element.

Abstract: An optical pickup which appropriately detects reflected light and return light reflected back from an information recording medium even if a laser light B1 emitted from a light source varies in wavelength. The transmittances of a half mirror to the laser light B1 emitted from the light source, and to the reflected light Bwr, Ber or the return light Brr reflected back from the information recording medium are preset according to a predetermined condition, i.e., Tpc(?c)/Tp(?)=(1?Ts(?)/(1?Tsc(?c))×(Tsc(?c)/Ts(?)).

Abstract: A reflection type compound prism and an optical pickup apparatus employing the same. As a light beam is passed through the compound prism, a size of the light beam in a direction perpendicular to a reference plane is reduced by a first reflection surface, propagated toward an objective lens by second and third reflection surfaces and the size restored by reflecting the light beam from a fourth reflection surface forming an angle less than 45° with respect to the reference plane so that a height of an optical system is reducible to obtain a small thin optical pickup with a desired NA. The second and third reflection surfaces are spaced apart in a direction perpendicular to the reference plane by an amount close to a diameter of the light beam at a point of incidence of the light beam with the compound prism.

Abstract: An optical pickup apparatus includes a light source and a light detector provided on a stem for detecting source emitted light reflected by an optical recording medium; and a light separating device, having first and second areas, for separating light incident thereon into a plurality of light components respectively directed in prescribed directions. The light detector includes a light receiver, divided into first and second light receiving regions for receiving the light components detected by those first and second areas. The first and second light receiving regions are located in a predetermined orientation determined in part by a light emitting point of the light source and a focal point on the light detector. The stem material and the wavelength emitted by the light source are selected to limit movement of that focal point in that orientation in response to temperature change of the apparatus.

Abstract: This invention is an optical pickup device having a composite optical element (32) which has a first diffraction grating (45) for splitting a light beam emitted from a light source (31) into zeroth-order light, plus-first-order light and minus-first-order light, a second diffraction grating (46) for diffracting the optical path of a return light beam from an optical disc (2), and a split prism (47) arranged at a position where the minus-first-order light diffracted by the second diffraction grating (46) is incident and adapted for splitting the minus-first-order light into a plurality of light beams. It also has a light receiving unit (35) for acquiring a focusing error signal FE by receiving each return light beam split by the split prism (47) and for acquiring a tracking error signal by receiving return light beams from the optical disc (2) of the plus-first-order light and the minus-first-order light split by the first diffraction grating (45).

Abstract: The present invention provides for a optical head device having a beam-guiding optical device to bring beams of different wavelengths which are emitted by separate light sources together onto the same optical axis or to guide the beams onto a common photo receiving device. The beam-guiding optical device includes an incident plane and an exit plane and the incident plane and the exit plane are back to back. One of the incident plane and the exit plane has a stair-like surface wherein a step height between neighboring treads in the stair-like surface is set to cause a phase difference of n wavelength to one of the beams passing through the neighboring treads and n is equal to 1, 2, 3 . . . .

Abstract: In an optical head device for recording/reproducing information on/from an optical recording medium, at least one laser light source emits a laser light beam provided with a first polarized light component and a second polarized light component which are perpendicular to each other. A plurality of optical elements transmit a return light beam reflected by the optical recording medium passes to the light receiving element. A transmission efficiency for the first polarized light component and a transmission efficiency for the second polarized light component in each optical element is made different. A total transmission efficiency for the first polarized light component and a total transmission efficiency for the second polarized light component, which are defined by the respective transmission efficiencies of all the optical elements, are made substantially identical.

Abstract: In an optical pickup used in a DVD player, a photo detector has a predetermined photo sensing area pattern for detecting a returning laser beam from an optical disc. The returning laser beam is originated from a first laser beam or a second laser beam. The first and the second laser beams are alternatively emitted from a two wavelength laser having first and second light sources. Either the first laser beam or the second laser beam travels to the optical disc through a grating, a polarizing beam splitter, a collimating lens, a rising mirror, and an object lens and is reflected by the optical disc. The reflected laser beam reflected from the optical disc travels to the photo detector as the returning laser beam through the object lens, the rising mirror, the collimating lens, and the polarizing beam splitter. The predetermined photo sensing area pattern enables the photo detector to detect the returning laser beam regardless of the origin of the returning laser beam.

Abstract: An anamorphic prism according to the invention comprises a first prism 2 made of a first light transmitting material and a second prism 3 made of a second light transmitting material, the first prism and the second prism being bonded together along predetermined respective planes thereof, the light beam entering the first prism being expanded or compressed in a particular direction of cross section of the light beam with a predetermined magnification, the expanded or compressed light beam being let to exit from the second prism 3 and proceed in a direction substantially same as the proceeding direction of the incident light beam entering the first prism 2.

Abstract: A light branching element which branches a light beam emitted from a light source and reflected on a magneto-optical recording medium is provided with four light branching portions, and three phase compensating means which give a fixed phase &dgr;M to a light beam branched by an M-th (M=2 to 4) light branching portion is disposed on paths of light beams branched by the three light branching portions except the first light branching portion of the four light branching portions. In this optical pickup, servo signals of four kinds of optical recording mediums are respectively detected using light beams detected by three or less groups of light receiving portions selected from among four groups of light receiving portions.

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