Abstract: A tunable light projector including the following is provided. A light source is configured to emit a light beam. A fixed optical phase modulator is disposed on a path of the light beam and is configured to modulate phases of the light beam. A tunable liquid crystal panel is disposed on the path of the light beam and a partial region of the tunable liquid crystal panel is configured to electrically switch the light beam between a structured light and a flood light. A driver is configured to control the light source and control the tunable liquid crystal panel to switch the light beam between the structured light and the flood light. The tunable liquid crystal panel includes: a first substrate; a second substrate; a liquid crystal layer; a first electrode layer; and a second electrode layer.

Abstract: Method and apparatus for non-invasive condition detection using an all fiber portable terahertz imaging system. An imaging system of the present disclosure may comprise a control module comprising a femtosecond pulsed laser configured to generate an output light beam, a dispersion compensation unit configured to receive the output light beam and transmit a laser light beam generated based upon the output light beam, a beam splitter configured to receive the laser light beam and divide the laser light beam into a pump light beam and a reference light beam; and a rapid scanning optical delay line configured to receive the pump light beam and transmit an exit light beam generated based upon the pump light beam, a patch probe comprising a transmitter module, an optics lens, and a detector module.

Abstract: An antenna control system in a base station system, and a configuration method of the antenna control system are disclosed. A method of controlling antennas in a multi-ALD (Antenna Line Device) system including ALDs and ports linked with multiple base stations is provided including receiving configuration command by one of ALDs from one of base stations, transferring configuration command by the ALD that received configuration command to each of remaining ALDs, and setting an antenna for controlling or port for linking by each ALD according to the configuration command. In accordance with some embodiments, a multi-ALD system for controlling a plurality of antennas includes ports for linking with multiple base stations, respectively, and ALDs for controlling the antennas, wherein the ALDs are linked for intercommunications with each other, to set an antenna to control or a port to link according to configuration command received from one of the base stations.

Abstract: An optical member having a concentric diffraction surface facing the outside, wherein the projection having a inclined surface concentric to the diffraction surface having an angle of inclination ? smaller than the angle of inclination ? is provided outside the diffraction surface having the largest ?, so that an interference of a cutting tool is avoided, and simultaneously, deterioration of a surface roughness may be restrained.

Abstract: Imaging systems may include camera modules that include multiple image sensor pixel arrays. A transparent lens substrate may be formed over the image pixel arrays. Lenses may be formed in the lens substrate such that each lens transmits light to a corresponding image sensor pixel array. Total internal reflection mitigation structures such as groove structures may be formed in one or more surfaces of the lens substrate between each of the lenses. The groove structures may include concentric ring shaped grooves in a surface of the lens substrate so that each lens is surrounded by a respective group of concentric ring shaped grooves. The groove structures may have a depth, angle, shape, and spacing that prevents total internal reflection of image light between the lenses so that high incident angle image light incident on a given pixel array is not captured by an adjacent pixel array.

Abstract: Systems and methods for long-term non-volatile non-rotating optical storage of digital information rely on storage elements that include optical storage media, an access subsystem configured to access bits of information from one of the storage elements, and a support structure configured to support multiple storage elements. A laser used to retrieve and/or record bits of digital information may be moved along two orthogonal dimensions while the storage element is non-rotating.

Abstract: Systems and methods for long-term non-volatile non-rotating optical storage of digital information rely on storage elements that include optical storage media, an access subsystem configured to access bits of information from one of the storage elements, and a support structure configured to support multiple storage elements. A laser used to retrieve and/or record bits of digital information may be moved along two orthogonal dimensions while the storage element is non-rotating.

Abstract: A method for designing a diffraction grating lens of the present invention is a method for designing a diffraction grating lens having a diffraction grating composed of a plurality of diffraction zones, the method including the steps of: (a) determining widths of the plurality of diffraction zones; and (b) determining an aspherical coefficient of a diffraction surface on which the diffraction grating is provided while the determined widths of the plurality of diffraction zones are fixed, after the step (a).

Abstract: An objective lens capable of converging light of a used wavelength with a satisfactory aberration on a recording medium is provided. An objective lens for converging light of a predetermined wavelength ? on a recording medium satisfies the following condition: |CML|+|CMF|<0.03?, where CML is an amount of a generated third-order coma aberration per 1 degree of tilt of the objective lens, and CMF is an amount of a generated third-order coma aberration per 1 degree of tilt of off-axis light.

Abstract: An objective lens for optical pickup and an optical pickup apparatus having the same are provided. The objective lens for optical pickup includes a light source side lens surface and a disc side lens surface. The light source side lens surface and the disc side lens surface each include an effective region disposed at a central region of the objective lens and a non-effective region disposed outside the effective region. An optical path changing element, disposed in the non-effective region of at least one of the light source side lens surface and the disc side lens surface, changes a path of light incident thereon.

Abstract: An objective lens for an optical pickup device is characterized in that compatibility of three types of optical discs, which are a BD, a DVD, and a CD, may be realized by a common objective lens, and a flare can be created by providing an over-spherical aberration when a third optical disc is used from a size relationship between a pitch on a central region side and a pitch on an intermediate region side across a boundary and a relationship of a direction of a step in the base structures superimposed in a central region and an intermediate region of 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 including an objective lens capable of enhancing temperature characteristics and wavelength characteristics, and which enables compatibility for three types of optical discs of BDs, DVDs, and CDs by using the objective lens in common, an optical information recording and reproducing apparatus, and an objective lens suitable for it. In a first optical path difference providing structure in which at least a first basic structure and a second basic structure are superimposed on each other, an amount of a level difference in an optical axis direction can be reduced, whereby it becomes possible to suppress the lowering of a diffraction efficiency when wavelength changes. Further, in the first basic structure and the second basic structure deterioration of the spherical aberration due to the change of the refractive index of the objective lens can be corrected by utilizing a phenomenon that the wavelength of the light source rises similarly due to a rise in the environmental temperature.

Abstract: An objective lens element which has excellent compatibility with optical discs having different base material thicknesses is provided. An objective lens element 141 has optically functional surfaces on an incident side and an exit side. Either one of the optically functional surfaces is divided into an inner part 131B including a rotational symmetry axis and an outer part 131F which is a ring-shaped region surrounding the inner part 131B. On the inner part 131B, a plurality of discontinuous steps are provided. The plurality of steps change in height in the same direction from the optical axis toward the outer part, and each of the steps causes a constant optical path difference longer than the wavelength ?1 to the first incident light beam 61 and causes a constant optical path difference shorter than the wavelength ?2 to the second incident light beam 62.

Abstract: In one embodiment, an optical pickup device includes a fixed portion 100, a movable portion 11, first and second elastic supporting members 12a and 12b, one and the other ends of which are secured to the fixed portion 100 and the movable portion 11, respectively, and an objective lens 8 secured to the movable portion 11. The objective lens 8 is arranged inside of the area that is defined between two lines that are respectively drawn from one and the other ends of the first elastic supporting member 12a perpendicularly to the first elastic supporting member 12a and outside of the area defined between the first and second elastic supporting members 12a and 12b.

Abstract: A lens surface of an objective lens includes an optical surface formed of a plurality of annular optical surfaces which include an approximately stair-shaped cross section and which are annularly partitioned centered around an optical axis of the objective lens, and a plurality of connecting surfaces that connect the plurality of mutually adjacent annular optical surfaces to each other. The plurality of connecting surfaces include cylindrical connecting surfaces formed of a cylindrical surface centered around the optical axis and a conical connecting surface formed of a conical surface centered around the optical axis, and the conical connecting surface connects the annular optical surface and the annular optical surface.

Abstract: An objective lens element having improved diffraction efficiency at least one of used wavelengths is provided. The objective lens element includes one surface including: a first region including an optical axis; and a second region surrounding the first region. A periodic first diffraction structure is formed on the first region, and a periodic second diffraction structure different from the first diffraction structure is formed on the second region. The objective lens element satisfies the following conditions. |A1?B1|<|A2?B2|??(1) |B1|?|B2|??(2) Here, A1 and B1 are diffraction orders at the first region to converge light of a first wavelength and light of a second wavelength on a recording surface, respectively, and A2 and B2 are diffraction orders at the second region to converge the light of the first wavelength and the light of the second wavelength on a recording surface, respectively.

Abstract: An objective lens a first optical path difference providing structure in which a first basic structure and a second basic structure are overlapped with each other. The first basic structure is a blaze-type structure which emits a Xth-order diffracted light flux, when the first light flux passes through the first basic structure, where the value of X is an odd integer. At least a part of the first basic structure arranged around an optical axis includes a step facing an opposite direction to the optical axis. The second basic structure is a blaze-type structure which emits a Lth-order diffracted light flux, when the first light flux passes through the second basic structure, where the value of L is an even integer. At least a part of the second basic structure arranged around the optical axis includes a step facing the optical axis.

Abstract: An object of the invention is to provide an optical disc device, an optical head, and an information processing device that enable to advantageously record or reproduce information with respect to an information recording medium having three or more information recording surfaces with light transmissive layers of different thicknesses from each other.

Abstract: In an optical head device which performs recording/reading of data in/from a high-density optical disc using an objective lens with a large NA, a saw-tooth shape diffraction element is used for also performing recording/reading of data in/from a conventional optical disc, such as DVD, CD, or the like. A step difference that produces an optical path length for blue light which is equal to or longer than the wavelength of the blue light and optical path lengths for red and infrared light which are shorter than the wavelengths of the red and infrared light is utilized so as to exert an inverse action on the blue light to those exerted on the red and infrared light. The effect of increasing the working distances for CD and DVD enables multiple compatibility. The optical element is integrally combined with the objective lens to perform a tracking servo following operation.

Abstract: An objective lens, an optical head, an optical disk apparatus and an information processing apparatus which can suppress deterioration of a focal spot caused by a drop in the diffraction efficiency. Inner and outer circumference areas converge a laser beam, out of laser beams having a wavelength ?1 which are diffracted by the inner and outer circumference areas, on a first information recording medium; the inner circumference area and a mid-circumference area converge a laser beam, out of the laser beams having a wavelength ?2 which are diffracted by the inner circumference area and the mid-circumference area, on a second information recording medium; and the diffraction efficiency of the laser beam having the wavelength ?2 is greater than the diffraction efficiency of the laser beam having the wavelength ?1.

Abstract: Provided is an optical pickup device capable of ensuring the compatibility among three types of optical discs, i.e., BDs, DVDs, and CDs, with a common objective lens and, in addition, capable of ensuring a sufficient working distance for CDs, and also provided are an optical information recording and reproducing device and an objective lens suitable for the optical information recording and reproducing device. On the objective lens, there is arranged a first optical path difference providing structure formed such that: the direction of step differences of a basic structure wherein the diffraction order of a blue-violet laser light flux become an odd order faces toward the opposite direction of the optical axis; the direction of step differences of a basic structure wherein the diffraction order of the blue-violet laser light flux become an even order faces toward the optical axis; and both the basic structures are overlapped together.

Abstract: An optical pickup apparatus, which reads signals recorded on first and second signal recording layers of an optical disc, includes: a laser diode; an objective lens to condense a laser beam to the first and second signal recording layers; and a collimating lens disposed in a light path of the laser beam between the laser diode and the objective lens and configured to correct a spherical aberration by moving in a light axis direction of the laser beam, and the objective lens includes a bifocal lens and is configured such that a second focal point does not coincide in position with the second signal recording layer when a first focal point coincides in position with the first signal recording layer, and the first focal point does not coincide in position with the first signal recording layer when the second focal point coincides in position with the second signal recording layer.

Abstract: Provided is an objective optical element which can appropriately correct degradation from spherical aberration upon fluctuation of a light source wavelength while maintaining light use efficiency, just by changing the magnification of the objective optical element, and which can record/reproduce information to/from different optical discs. Also provided is an optical pickup device using the objective optical element. When a light flux having two different wavelengths ?11, ?12 (wherein ?11<?12 and ?12??11=5 nm) within a range of wavelength ?1 is introduced to the objective optical element to measure the wavefront aberration, the following third order and fifth order spherical aberrations in unit of ?rms are obtained: SA3(?11), SA5(?11), SA3(?12), SA5(?12). If ?SA3=|SA3(?12)?SA3(?11)|, ?SA5=|SA5(?12)?SA5(?11)|, the following expression is satisfied: 0.18>?SA3>?SA5>0 (1).

Abstract: A complex objective lens composed of a hologram and an objective lens, capable of realizing stable and high-precision compatible reproducing/recording of a BD with a base thickness of about 0.1 mm for a blue light beam (wavelength ?1) and a DVD with a base thickness of about 0.6 mm for a red light beam (wavelength ?2). In an inner circumferential portion of the hologram, a grating is formed, which has a cross-sectional shape including as one period a step of heights in the order of 0 time, twice, once, and three times a unit level difference that gives a difference in optical path of about one wavelength with respect to a blue light beam, from an outer peripheral side to an optical axis side. The hologram transmits a blue light beam as 0th-order diffracted light without diffracting it, and disperses a red light beam passing through an inner circumferential portion as +1st-order diffracted light and allows it to be condensed by an objective lens.

Abstract: An optical head (10) transmits a light beam to an optical disc (30), in which light-transmitting layers largely change in thickness, and includes a degree-of-diversion/convergence enlarging member (20) fixed between a collimating lens (4) and an objective lens (6). The diversion/convergence enlarging member (20) reduces a moving range of the collimating lens (4), and allows the optical head (10) to be miniaturized.

Abstract: An objective lens relating to the present invention includes a first optical path difference providing structure in which a first basic structure and a second basic structure are overlapped with each other. The first basic structure is a blaze-type structure which emits a Xth-order diffracted light flux, when the first light flux passes through the first basic structure, where the value of X is an odd integer. At least a part of the first basic structure arranged around an optical axis includes a step facing an opposite direction to the optical axis. The second basic structure is a blaze-type structure which emits a Lth-order diffracted light flux, when the first light flux passes through the second basic structure, where the value of L is an even integer. At least a part of the second basic structure arranged around the optical axis includes a step facing the optical axis.

Abstract: In the invention, a movable lens varying the rate of convergence or divergence of light reaching an objective lens by moving in an optical axis direction has its position adjusted to correspond to ambient temperature. The objective lens is arranged to be tilted with respect to an optical axis of light reaching the objective lens from the movable lens. First coma aberration of which the amount produced varies according to movement of the movable lens, and second coma aberration of which the amount produced varies due to variation in the warping state of an optical disc that is caused along with variation in ambient temperature both occur in the radius direction of the optical disc, and the objective lens has its tilting direction adjusted such that the first coma aberration and the second coma aberration have their increasing and decreasing directions of the amount of coma aberration produced with respect to variation in ambient temperature reversed.

Abstract: It is aimed to provide an optical head, an optical head manufacturing method and an optical disc device capable of correcting coma aberration generated due to different positions of emission points of a plurality of laser lights having different wavelengths. A two-wavelength laser light source 1 is arranged to correct coma aberration generated in a radial direction of a CD 80 in the case where an objective lens 6 is tilted to locate an inner peripheral end of the objective lens 6 in the radial direction of the CD 80 lower than an outer peripheral end thereof, and an objective lens actuator 9 tilts the objective lens 6 to locate the inner peripheral end of the objective lens 6 in the radial direction of the CD 80 lower than the outer peripheral end thereof.

Abstract: An optical head includes a blue-violet laser light source for emitting a blue-violet laser beam, a mirror with a diffraction grating for transmitting and reflecting the blue-violet laser beam at a predetermined ratio, and a front monitor sensor for receiving transmitted light or reflected light from the mirror with a diffraction grating and creating an APC signal for controlling an output of the blue-violet laser light source. The mirror with a diffraction grating includes a first surface which the blue-violet laser beam enters, and a second surface facing the first surface. The first surface and the second surface are mutually parallel. A reflecting coat for transmitting and reflecting the blue-violet laser beam at a predetermined ratio is formed on the first surface, and a diffraction grating is formed on the second surface.

Abstract: An objective lens for an optical information recording/reproducing apparatus, at least one of optical surfaces of the objective lens comprising a diffraction surface having a diffraction structure defined by an optical path difference function, and wherein: the diffraction surface has a first region contributing to converging first and second light beams and having a diffraction structure configured such that diffraction orders at which the diffraction efficiencies are maximized for the first and second light beams are 1st order; the diffraction surface has a second region located outside the first region, and the second region is configured to contribute to converging the first light beam and not to contribute to convergence of the second light beam; and the objective lens satisfies a condition: 35<P2×f2<200 ??(1).

Abstract: In an optical head device which performs recording or reading of data in/from a high-density optical disc using an objective lens with a large NA, a saw-tooth shape diffraction element is used for also performing recording or reading of data in/from a conventional optical disc, such as DVD, CD, or the like. A step difference that produces an optical path length for blue light which is equal to or longer than the wavelength of the blue light and optical path lengths for red and infrared light which are shorter than the wavelengths of the red and infrared light is utilized so as to exert an inverse action on the blue light to those exerted on the red and infrared light. The effect of increasing the working distances for CD and DVD enables multiple compatibility. The above optical element is integrally combined with the objective lens to perform a tracking servo following operation.

Abstract: Provided is a method for forming a near-field light generating element, which is capable of sufficiently suppressing the unevenness of a waveguide surface and the distortion within the waveguide. The forming method comprises the steps of: forming a first etching stopper layer on a lower waveguide layer; forming a second etching stopper layer; forming, on the second etching stopper layer, a plasmon antenna material layer; performing etching with the second etching stopper layer used as a stopper, to form a first side surface of plasmon antenna; forming a side-surface protecting mask so as to cover the first side surface; and performing etching with the first and second etching stopper layers used as stoppers, to form the second side surface. By providing the first and second etching stopper layer, over-etching can be prevented even when each etching process takes enough etch time, which allows easy management of etching endpoints.

Abstract: A compatible near field optical recording/reproducing apparatus includes a solid immersion lens unit including a first lens, which has an aspherical surface in which light incident from the first light source is condensed, and a second lens, which realizes a high numerical aperture via a near field effect by light condensed by the first lens and has an aspherical surface. An effective beam size-controlling device controls an effective size of a light beam transmitted to the solid immersion lens unit such that either near field light or far field light is transmitted to an information storage medium by the solid immersion lens unit and a focal point adjusting optical system adjusts a focal position of light transmitted to the information storage medium according to the type of the information storage medium.

Abstract: An optical pickup apparatus comprises: a first laser diode that generates a first laser beam having a first wavelength; a second laser diode that generates a second laser beam having a second wavelength longer than the wavelength; a third laser diode that generates a third laser beam having a third wavelength longer than the first wavelength and shorter than the second wavelength; an objective lens having an inner, outer, intermediate regions on an incident surface, the first laser beam being condensed on a signal recording layer of a first optical disc by condensing actions of the inner and outer regions, the second laser beam being condensed on a signal recording layer of a second optical disc by condensing actions of the inner and intermediate regions, the third laser beam being condensed on a signal recording layer of a third optical disc by condensing actions of the inner and intermediate regions.

Abstract: An objective optical system for an optical information recording/reproducing apparatus for recording/reproducing for first, second and third optical discs by selectively using three types of substantially collimated light beams including first, second and third light beams respectively having first, second and third wavelengths, wherein at least one of optical surfaces of the objective optical system comprises a diffraction surface having a diffraction structure, the diffraction surface includes a first region defined by first and second optical path difference functions, a second region defined by at least one type of optical path difference function, and a third region defined by at least one type of optical path difference function, the first region satisfies a condition: ?0.15<f1/fD11<?0.03??(1), where fD11=?1/(2×P112×m11×?), and the diffraction surface satisfies a condition: ?0.05<(?13(h3)??13(h2))/(m13×f1)<?0.005??(2).

Abstract: A multilayer optical recording system to record information with light includes a lens unit, a recording medium, and a microscopic drive unit. The lens unit includes a metamaterial lens or a plasmon lens. The metamaterial lens has a first dielectric member in which first microstructures are implanted in a substantially regular manner. The plasmon lens has an aperture. The aperture is a hole or a slit created in a metal film. The microscopic drive unit is configured to adjust a relative position between the lens unit and the recording medium. In addition, the principal plane is placed to be in contact with the lens unit or to have a gap between the principal plane and the lens unit. Furthermore, the second microstructures are arranged periodically in a direction substantially perpendicular to the principal plane of the recording medium.

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 according to the present invention includes: a first light source that emits light with a first wavelength; a beam splitter that splits the light emitted from the first light source into a first light beam traveling in a first direction and a second light beam traveling in a second direction different from the first direction; a first collimator lens for changing degrees of divergence of the first light beam; a first mirror that changes the traveling directions of the first light beam, of which the degrees of divergence have been changed; a first objective lens for converging the first light beam, which has had its traveling directions changed, toward a storage layer of a first optical disk; a mover that holds the first objective lens; a first photodetector that receives the first light beam reflected from the storage layer of the first optical disk and converts it into an electrical signal; a condenser lens for condensing the second light beam; and a second photodetector that receives the sec

Abstract: Provided is an objective lens for an optical pickup apparatus. The objective lens collects diffracted light generated by an optical path difference giving structure onto the information recording surface of an optical information recording medium as a spot and suppresses fluctuation of diffraction efficiency due to a change of using wavelength. The optical pickup apparatus using such objective lens is also provided. The total diffraction efficiency can be improved by adjusting a wavelength at which the diffraction efficiencies of a plurality of basic structures forming the optical path difference giving structure in the objective lens are maximum, in accordance with a basic structure.

Abstract: Provided are an optical pickup apparatus and an objective lens which can record and/or reproduce information for discs with different recording densities and can realize simplification of the structure of themselves and reducing cost. When the expression (1) is satisfied, step differences of a step structure can be further reduced than those in the case that d1=?1(n?1) holds, and fine grooves corresponding to a steps structure, formed on an optical-surface transfer surface of a mold for molding the objective lens become shallow, to be easily processed. In addition, the moldability is enhanced because the material of the objective lens easily enters the inner portion of the grooves. Further, a fluctuation of a diffraction efficiency caused when wavelength of a light flux changes or temperature changes is reduced so that information can be recorded and/or reduced stably.

Abstract: A disclosed optical pickup for performing at least recording, reproduction, or deletion of information on a first, second, third, and fourth optical recording media having different recording densities includes a first light source configured to emit first light having a first wavelength ?1 corresponding to the first and second optical recording media; a second light source configured to emit second light having a second wavelength ?2 corresponding to the third optical recording medium; a third light source configured to emit third light having a third wavelength ?3 corresponding to the fourth optical recording medium; an objective lens configured to focus the first light, the second light, and the third light on corresponding recording surfaces of the first, second, third, and fourth optical recording media; and an aberration correcting unit between the objective lens and the first, second, and third light sources.

Abstract: An optical pickup device includes a first laser element that emits first laser light, a second laser element that emits second laser light of which the wavelength is longer than that of the first laser light, an optical path composition element that composes the first laser light and the second laser light to one optical path, a wavelength selective element that acts on the composed first or second laser light; and an objective lens that condenses the first laser light and the second laser light on an optical disk. The magnitude of the power of the wavelength selective element as a lens with respect to the second laser light is larger than the magnitude of the power of the wavelength selective element as a lens with respect to the first laser light. Accordingly, it may be possible to reduce the optical pickup device and the optical disk apparatus in size.

Abstract: There is provided an objective optical system used for information recording/reproducing for three types of optical discs. The objective optical system includes an objective lens, and a diffraction structure formed on an optical surface. The diffraction structure includes a first area for contributing to converging the third light beam. The first area includes first and second steps defined by first and second optical path difference functions, respectively. The first step is configured such that diffraction orders at which diffraction efficiencies for the first, second and third light beams are maximized are 1st order, 0-th order and 0-th order, respectively. The first step satisfies a condition: ?0.36×102<P12×f1+5.0×103×(n1?n3)<1.80×102??(1) The second step is configured such that diffraction orders at which diffraction efficiencies for the first, second and third light beams are maximized are 2nd order, 1st order and 1st order, respectively.

Abstract: An optical pickup includes: a first emission unit emitting an optical beam with a first wavelength corresponding to a first optical disc; a second emission unit emitting an optical beam with a second wavelength, which is longer than the first wavelength, corresponding to a second optical disc different from the first optical disc; a third emission unit emitting an optical beam with a third wavelength, which is longer than the second wavelength, corresponding to a third optical disc different from the first and second optical discs; a condensing optical device condensing, on a signal recording surface of a corresponding optical disc, the optical beams emitted from the first to third emission units; and a diffraction unit provided in the condensing optical device, which is disposed on the optical path of the optical beams with the first to third wavelengths.

Abstract: An optical head device compatible to different types of optical discs and capable of guaranteeing a sufficiently wide dynamic range for a low density optical disc, and the like are provided. The optical head device includes a plurality of light sources switchably usable; an objective lens for converging light emitted from one of the plurality of light sources to an information recording layer of an optical disc; and a light detector for receiving the light reflected by the information recording layer and outputting an electric signal based on the amount of the received light. The plurality of light sources include a first light source for emitting light having a first wavelength and a second light source for emitting light having a second wavelength shorter than the first wavelength.

Abstract: An objective lens relating to the present invention includes a first optical path difference providing structure in which a first basic structure and a second basic structure are overlapped with each other. The first basic structure is a blaze-type structure which emits a Xth-order diffracted light flux, when the first light flux passes through the first basic structure, where the value of X is an odd integer. At least a part of the first basic structure arranged around an optical axis includes a step facing an opposite direction to the optical axis. The second basic structure is a blaze-type structure which emits a Lth-order diffracted light flux, when the first light flux passes through the second basic structure, where the value of L is an even integer. At least a part of the second basic structure arranged around the optical axis includes a step facing the optical axis.

Abstract: An objective lens includes a first optical path difference providing structure in which a first basic structure and a second basic structure are overlapped together, and a second optical path difference providing structure in which a third basic structure, a fourth basic structure, and a fifth basic structure are overlapped together. The first and third basic structures emit diffracted light fluxes with the same diffraction order having the maximum light amount. The second and fourth basic structures emit diffracted light fluxes with the same diffraction order having the maximum light amount. The fifth basic structure emits 0th-order diffracted light fluxes with the maximum light amount, for the first light flux, emits 0th-order diffracted light fluxes with the maximum light amount, for the second light flux, and emits Gth-order diffracted light fluxes with the maximum light amount, for the third light flux, where G is an integer excluding zero.

Abstract: An optical pickup apparatus compatible with at least two types of optical recording media, using light beams having respective different wavelengths for recording and reading information, the optical pickup apparatus including two laser light sources to emit light beams having the different wavelengths, a holographic lens including a holographic ring to transmit the light beams incident in an inner region of the holographic ring, and to diffract a specific light beam among the light beams emitted from the laser light sources incident in an outer region relative to the inner region, an objective lens to focus the light beams passed through the holographic ring lens on the respective information recording surfaces of the two types of the optical recording media, optical elements to alter optical paths of the light beams reflected from the information recording surfaces of the optical recording media to corresponding photodetectors.

Abstract: An optical disk reader or read/write system for CD or DVD formats. First and second laser diodes operating at different wavelengths have their output beams collimated and directed at a single element objective lens, and are then reflected off the disk back through the lens to a photodetector. The single element objective lens has a central aperture zone and an outer aperture zone, the central zone being profiled to operate at a first numerical aperture at approximately 0.45 and the output beam of the first laser diode is confined to the central aperture zone. The outer aperture zone together with the central aperture zone are profiled to operate at a second numerical aperture, for example 0.60 wherein the output beam of the second laser diode has ray fans extending across the full aperture of the single element objective lens.