Abstract: In a lens module, a sidewall of a lens barrel includes a first wall section that surrounds at least one access hole, and a second wall section that is other than the first wall section. The first wall section has a first inner circumferential surface and a first distance defined between the first inner circumferential surface and an outer circumferential surface of the at least one lens. The second wall section has a second inner circumferential surface and a second distance defined between the second inner circumferential surface and the outer circumferential surface of the at least one lens. The first distance is larger than the second distance.

Abstract: A system may render glyphs based on stored textures without loss of quality at subpixel scales. The system may determine a content of a pixel of a display corresponds to a glyph, determine a subpixel alignment offset of a specified screen coordinates for the glyph with respect to the pixels of the display, based on the subpixel alignment offset, select one or more versions of the glyph from a plurality of versions of the glyph, a first version of the glyph of the plurality of versions of the glyph having a corresponding first subpixel alignment offset and a second version of the glyph of the plurality of versions of the glyph having a corresponding second subpixel alignment offset, and generate a display version of the pixel based on the selected one or more versions of the glyph and the subpixel alignment offset of the specified screen coordinates.

Abstract: An optical laser beam director assembly is disclosed. The beam director assembly includes a monolithic optics piece formed of transparent optical material, a laser source is coupled to the monolithic optics piece to provide a laser beam to the optics piece, and a beam steerer connected to the optics piece to direct the laser beam output from the optics piece onto a target.

Abstract: A structured light projectors includes an illuminator configured to emit illumination light, a pattern mask configured to project structured light by partially transmitting the illumination light, and a lens configured to project the structured light, wherein the pattern mask includes a first lens distortion compensation region including a plurality of opaque first light shielding patterns having a first pattern width, respectively, and a second lens distortion compensation region surrounding the first lens distortion compensation region, the second lens distortion compensation region including a plurality of opaque second light shielding patterns having a second pattern width, respectively, wherein the second pattern width is less than the first pattern width.

Abstract: A device including a near field transducer, the near field transducer including gold (Au), silver (Ag), copper (Cu), or aluminum (Al), and at least two other secondary atoms, the at least two other secondary atoms selected from: boron (B), bismuth (Bi), indium (In), sulfur (S), silicon (Si), tin (Sn), manganese (Mn), tellurium (Te), holmium (Ho), lutetium (Lu), praseodymium (Pr), scandium (Sc), uranium (U), barium (Ba), chlorine (Cl), cesium (Cs), dysprosium (Dy), europium (Eu), fluorine (F), germanium (Ge), hydrogen (H), iodine (I), rubidium (Rb), selenium (Se), terbium (Tb), nitrogen (N), oxygen (O), carbon (C), antimony (Sb), gadolinium (Gd), samarium (Sm), thallium (Tl), cadmium (Cd), neodymium (Nd), phosphorus (P), lead (Pb), hafnium (Hf), niobium (Nb), erbium (Er), zinc (Zn), magnesium (Mg), palladium (Pd), vanadium (V), zinc (Zn), chromium (Cr), iron (Fe), lithium (Li), nickel (Ni), platinum (Pt), sodium (Na), strontium (Sr), calcium (Ca), yttrium (Y), thorium (Th), beryllium (Be), thulium (Tm), erbium

Abstract: A super-resolution system for nano-patterning is disclosed, comprising an exposure head that enables a super-resolution patterning exposures. The super-resolution exposures are carried out using electromagnetic radiation and plasmonic structures, and in some embodiments, plasmonic structures having specially designed super-resolution apertures, of which the “bow-tie” and “C-aperture” are examples. These apertures create small but bright images in the near-field transmission pattern. A writing head comprising one or more of these apertures is held in close proximity to a medium for patterning. In some embodiments, a data processing system is provided to re-interpret the data to be patterned into a set of modulation signals used to drive the multiple individual channels and multiple exposures, and a detection means is provided to verify the data as written.

Abstract: A forward-viewing spectrally encoded endoscope (SEE) probe includes a light guiding component, a light focusing component, and a grating component arranged along a longitudinal axis of a drive cable. The SEE probe is configured for guiding light from the light guiding component, through the light focusing component, and to the grating component, and then forwarding a spectrally dispersed light line from the grating component towards an image plane. One or more of the light guiding component, the light focusing component, and the grating component is arranged at an angle with respect to the longitudinal axis of the drive cable so that at least one wavelength of the spectrally dispersed light line goes to the direction of axis of the drive cable.

Abstract: Laser module including a meniscus collimating lens. In some embodiments, a monolithic material having an index of at least 2.0 provides a concave lens surface proximal to an emission surface of the laser and a convex lens surface distal from the emission surface. In some embodiments, a perimeter of the collimating lens has a face-flat that may be disposed directly against a reference surface while the concave lens surface is separated from the emission surface. The meniscus lens may advantageously provide reduced angle of ray incidence and require lower asphericity relative to a plano-convex collimating lens.

Abstract: Some embodiments of the present inventive concept provide optical coherence tomography (OCT) systems for integration with a microscope. The OCT system includes a sample arm coupled to the imaging path of a microscope. The sample arm includes an input beam zoom assembly including at least two movable lenses configured to provide shape control for an OCT signal beam; a scan assembly including at least one scanning mirror and configured for telecentric scanning of the OCT signal beam; and a beam expander configured to set the OCT signal beam diameter incident on the microscope objective. The shape control includes separable controls for numerical aperture and focal position of the imaged OCT beam.

Abstract: A liquid droplet forming apparatus includes a liquid retention unit configured to retain particle suspension liquid in which precipitated particles are suspended; a membrane member, in which a nozzle is formed, configured to discharge the particle suspension liquid retained in the liquid retention unit, as a liquid droplet, by vibration from the nozzle; and a particle state detection unit configured to detect, from a side of the liquid retention unit, a particle state of the precipitated particle around the nozzle in the particle suspension liquid.

Abstract: An endoscope includes a light outlet surface at the distal end of the endoscope and a controllable light-refracting device for controllable refraction of illuminating light by a shapeable phase interface between two fluids, such that the controllable light-refracting device is disposed at the distal end of the endoscope.

Abstract: A method and apparatus for optical metrology is disclosed. There is disclosed, for example, a method involving a radiation intensity distribution for a target measured using an optical component at a gap from the target, the method including calculating a correction factor for the variation of radiation intensity of the radiation intensity distribution as a function of variation of the distance of the gap.

Abstract: Some embodiments of the present inventive concept provide optical coherence tomography (OCT) systems for integration with a microscope. The OCT system includes a sample arm coupled to the imaging path of a microscope. The sample arm includes an input beam zoom assembly including at least two movable lenses configured to provide shape control for an OCT signal beam; a scan assembly including at least one scanning mirror and configured for telecentric scanning of the OCT signal beam; and a beam expander configured to set the OCT signal beam diameter incident on the microscope objective. The shape control includes separable controls for numerical aperture and focal position of the imaged OCT beam.

Abstract: A microparticle measuring apparatus for highly accurately detecting the position of a microparticle flowing through a flow channel includes a light irradiation unit for irradiating a microparticle flowing through a flow channel with light, and a scattered light detection unit for detecting scattered light from the microparticle, including an objective lens for collecting light from the microparticle, a light splitting element for dividing the scattered light from the light collected by the objective lens, into first and second scattered light, a first scattered light detector for receiving an S-polarized light component, and an astigmatic element disposed between the light splitting element and the first scattered light detector, and making the first scattered light astigmatic. A relationship between a length L from a rear principal point of the objective lens to a front principal point of the astigmatic element, and a focal length f of the astigmatic element satisfies the following formula I. 1.5f?L?2.

Abstract: The light source device includes a first light source, a second light source, and a substrate including a base member. A first wiring and a second wiring are disposed on the substrate. The first wiring has a connection part including connection parts such that the first light source is electrically connected in series and a connection part including connection parts such that the second light source is electrically connected in series. The base member is provided with at least one through-hole at each portion where the connection parts of the connection parts are disposed, and includes a protrusion in a vicinity of the through-hole such that the protrusion protrudes along a surface of the base member in a direction intersecting the first wiring. The second wiring includes at least one detour path in a vicinity of the protrusion, detouring around the through-hole with an insulation distance from the through-hole.

Abstract: A part to be centered during an assembly process includes an effective portion which performs a function and is shaped for insertion into a hole, a reference portion extended from the effective portion and formed substantially perpendicular to a center axis of the effective portion, and an aligning portion extended from the effective portion and formed around the effective portion. When the effective portion of the part is inserted into the hole, a center of the effective portion is automatically aligned with a centerline of the hole.

Abstract: Provided is a recording apparatus including a self-excited oscillation semiconductor laser that has a double quantum well separate confinement heterostructure and includes a saturable absorber section to which a negative bias voltage is applied and a gain section into which a gain current is injected, an optical separation unit, an objective lens, a light reception element, a pulse detection unit, a reference signal generation unit, a phase comparison unit, a recording signal generation unit, and a control unit.

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: When bnt denotes the length adjustment amount of a front edge portion of an nT recording mark (n: integer, T: channel clock length) and cnT denotes the length adjustment amount of a rear edge portion thereof with respect to a channel clock reference, d denotes a minimum value of n and k denotes a maximum value of n, the length adjustment amount bdT of a front edge portion of a shortest recording mark dT, the length adjustment amount cdT of a rear edge portion of the shortest recording mark dT, the length adjustment amount bkT of a front edge portion of a longest recording mark kT and the length adjustment amount ckT of a rear edge portion of the longest recording mark dT satisfy bdT+cdT>bkT+ckT.

Abstract: An optical element having compatibility among two or more wavelengths and having an excellent converging performance for light with each wavelength, and an optical head apparatus using the optical element are provided. An optical element according to the present disclosure has a first region including an optical axis and a second region formed around the outer circumference of the first region. The first region and the second region respectively have a first diffraction structure and a second diffraction structure each cyclically formed on an aspheric surface and having a step-like cross section. In the first region, the number of steps included between top portions of the first diffraction structure is different from the number of steps included between the optical axis and a top portion that is closest to the optical axis in the first diffraction structure.

Abstract: A data storage media may have at least a multi-layer recording lamination with a predetermined coercivity. The multi-layer recording lamination can be configured to record at least one servo format mark for a plurality of data tracks with a solid immersion mirror and program a data bit on the multi-layer recording lamination with a near field transducer.

Abstract: The reliability of a super-resolution optical information recording medium whose capacity can be increased is increased. On an optical information recording medium (11) according to the present invention, a content is recorded as a pit group formed such that an average length Tm [nm] of a minimum mark length and a minimum space length becomes shorter than an optical system resolution limit, and reading speed information designating a reading speed in a range from 2×(4.92×Tm/149) [m/s] to less than (10000/60)×2×?×(24/1000) [m/s] is recorded as a reading speed for reproducing the content.

Abstract: An apparatus includes a waveguide configured to deliver light to a transducer region. The apparatus also includes a plasmonic transducer that has two metal elements configured as side-by-side plates on a substrate-parallel plane with a gap therebetween. The gap is disposed along the substrate-parallel plane and has an input end disposed proximate the transducer region and an output end. The transducer is configured to provide a surface plasmon-enhanced near-field radiation pattern proximate the output end in response to the light received by the waveguide.

Abstract: Assuming that third-order coma aberration per unit angle generated by tilt of BD (60) in recording or reproducing information on or from BD (60) is CMDbd, third-order coma aberration per unit angle generated by tilt of CD (80) in recording or reproducing information on or from CD (80) is CMDcd, third-order coma aberration per unit angle generated by tilt of a compatible objective lens (8) in recording or reproducing information on or from BD (60) is CMLbd, and third-order coma aberration per unit angle generated by tilt of the compatible objective lens (8) in recording or reproducing information on or from CD (80) is CMLcd, a sine condition deviation amount (SCbd) in recording or reproducing information on or from BD (60) is expressed by CMDbd+CMLbd, a sine condition deviation amount (SCcd) in recording or reproducing information on or from CD (80) is expressed by CMDcd+CMLcd, and the sine condition deviation amount (SCbd) and the sine condition deviation amount (SCcd) satisfy SCbd>0 and SCcd<0.

Abstract: An optical read/write device in accordance with an embodiment of the present invention includes a lens portion configured to irradiate light emitted from a light source to an optical recording medium, and the lens portion includes: a flexible shape-variable lens; and an electrode portion provided on the shape-variable lens. The shape of the shape-variable lens can be changed when voltage is applied to the electrode.

Abstract: An optical information recording medium includes a substrate that has a recessed portion on a surface thereof, a recording layer, and a reflective layer. By combination of ranges of an optical density of the recording layer and a depth of the recessed portion of the substrate, degradation of reflectance is suppressed.

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: Provided are an objective lens driving unit that maintains the electrical connection between suspension wires and winding bosses. The objective lens driving unit includes a plurality of winding bosses disposed at a side of the frame, each having a projection formed at its end and extending in a direction in which a suspension wire extends.

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: Assuming that third-order coma aberration per unit angle generated by tilt of BD (60) in recording or reproducing information on or from BD (60) is CMDbd, third-order coma aberration per unit angle generated by tilt of CD (80) in recording or reproducing information on or from CD (80) is CMDcd, third-order coma aberration per unit angle generated by tilt of a compatible objective lens (8) in recording or reproducing information on or from BD (60) is CMLbd, and third-order coma aberration per unit angle generated by tilt of the compatible objective lens (8) in recording or reproducing information on or from CD (80) is CMLcd, a sine condition deviation amount (SCbd) in recording or reproducing information on or from BD (60) is expressed by CMDbd+CMLbd, a sine condition deviation amount (SCcd) in recording or reproducing information on or from CD (80) is expressed by CMDcd+CMLcd, and the sine condition deviation amount (SCbd) and the sine condition deviation amount (SCcd) satisfy SCbd>0 and SCcd<0.

Abstract: An apparatus includes a waveguide configured to deliver light to a transducer region. The apparatus also includes a plasmonic transducer that has two metal elements configured as side-by-side plates on a substrate-parallel plane with a gap therebetween. The gap is disposed along the substrate-parallel plane and has an input end disposed proximate the transducer region and an output end. The transducer is configured to provide a surface plasmon-enhanced near-field radiation pattern proximate the output end in response to the light received by the waveguide.

Abstract: Provided are an optical pickup and an optical system using the same. The optical pickup may include an aperture that is disposed at a side where a light beam is incident on an objective lens. The aperture may limit a range of the light beam such that a width of the light beam incident on the objective lens in a first direction is less than a width in a second direction that is perpendicular to the first direction.

Abstract: A disclosed objective lens includes: a lens having an entrance surface and an emission surface; and an anti-reflection coat formed on the emission surface, wherein a transmittance T1—0 [%] of the anti-reflection coat when an incident angle of a first laser beam having a first wavelength ?1 (390 nm??1?430 nm) is 0°, and the transmittance T1—40 [%] of the anti-reflection coat when the incident angle of the first laser beam is 40° satisfy 0.95?T1—0/T1—40?1.05, and a transmittance T2—0 [%] of the anti-reflection coat when an incident angle of a second laser beam having a second wavelength ?2 (630 nm??2?680 nm) is 0° and a transmittance T2—40 [%] of the anti-reflection coat when the incident angle of the second laser beam is 40° satisfy 0.85?T2—0/T2—40?0.97.

Abstract: An optical pickup assembly includes a first optical pickup unit (OPU) and a second OPU. The OPUs are either stacked on each other in separate housings or integrated together in a common housing such that the OPUs are arranged laterally across a tape path and are positioned at a longitudinal position along the tape path.

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 objective lens element that can suppress occurrence of an aberration is disclosed. Sawtooth-like diffraction structures having different height and cycles (pitches) are provided on an inner part R21 and an outer part R22, respectively. A curved surface M211 extending at an intermediate level of recesses and projections of the sawtooth-like diffraction structure provided on the inner part R21, and a curved surface M212 extending at an intermediate level of recesses and projections of the sawtooth-like diffraction structure provided on the outer part R22 are smoothly connected to each other. Even when wavelength of the light source and/or the environmental temperature change, a phase shift does not occur between the inner part R21 and the outer part R22, and a decrease in diffraction efficiency and occurrence of an aberration can be suppressed.

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: An optical element has at least one surface divided into a plurality of regions and includes: a first region configured to converge light with a wavelength ?1 onto a storage surface of a first optical disc and converge light with a wavelength ?2 onto a storage surface of a second optical disc; and a second region formed around the outer circumference of the first region and configured to converge light with the wavelength ?1 onto the storage surface of the first optical disc. The second region has a concave-convex structure concentrically formed on an aspheric surface and having a cross section being a saw teeth shape. The concave-convex structure is formed by a plurality of different saw teeth shapes, and the plurality of different saw teeth shapes respectively give different phase differences corresponding to substantially integer multiples of the wavelength ?1, for light with the wavelength ?1.

Abstract: Aspects of the disclosure provide an apparatus. The apparatus includes a collimator configured to have a plurality of positions, and a controller configured to control the collimator to move to a predetermined position associated with a data layer of an optical storage medium to collimate a light beam. The collimated light beam is then focused onto the data layer of the optical storage medium.

Abstract: An optical pickup device corresponding to a plurality of media is provided. The optical pickup device includes a light emitting system and a light receiving system including a plurality of light sources and a light transmission system shared by the light emitting system and the light receiving system, configured to irradiate light on a medium, and receive light reflected from the medium. The light transmission system irradiates light from the light emitting system to be appropriately focused on the medium, receives light reflected from the medium, and transports light to the light receiving system. The light transmission system includes one beam splitter corresponding to the light emitting system and the light receiving system and a position-changing collimating lens shared to correspond to a plurality of media. The position-changing collimating lens is disposed between the beam splitter and the medium, the position being controlled according to optical characteristics of the media.

Abstract: An objective lens element having improved diffraction efficiency at 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 optical pickup device includes a single objective lens (1) that focuses a light beam to irradiate an optical disk, and an objective lens actuator (29) that drives the objective lens (1). The objective lens actuator (29) includes a lens holder (2) that holds the objective lens (1). Two gaps (Ga, Gb) are formed between the lens holder (2) and the objective lens (1). In an xy plane in which the center of the objective lens (1) is defined as an origin, the tracking direction is defined as an y axis, and the tangential direction of tracks of the optical disk is defined as an x axis, the gap (Ga) is positioned at least in the first quadrant of the xy plane, and the gap (Gb) is positioned at least in the third quadrant of the xy plane.

Abstract: An objective optical system for information recording/reproducing, at least one of optical surfaces of the objective optical system comprising a diffraction surface including a first region contributing to converging first, second and third beams and including a diffraction structure formed such that use diffraction orders for the first, second and third beams are 1st-orders and a condition 0.03<(?B11??1)/?1<0.40 is satisfied; a second region contributing to converging only the first and second beams and including a diffraction structure formed such that the use diffraction orders are 1st-orders and a condition: ?0.35<(?B12??B11)/?1<0.35 is satisfied; and a third region contributing to converging only the first beam and including a diffraction structure formed such that the use diffraction order for the first beam is an odd order and a condition: ?0.23<m13 ((?B13??1)/?1)<0.23 is satisfied.

Abstract: According to one embodiment, a lens driving device includes a fixed member, a movable member, a support part, and a coil. The movable member is configured to retain a lens and a magnet. The supporting part is configured such that a guide member placed substantially in parallel with a lens optical axis supports the movable member at plural positions symmetric with respect to the lens optical axis while the movable member is movable in a direction of the lens optical axis with respect to the fixed member. The coil is configured such that a driving force is generated for the movable member by interaction with the magnet provided in the fixed member.

Abstract: In an optical pickup device for use in recording and reproducing on an optical recording medium, such as a CD or DVD, banks are formed on both sides of an adhesive agent application position for adhering an optical device, such as a photodetector or a laser diode, in an optical pickup case. At this time, a bank on the side of an optical path is formed higher than a height of an outer bank, and an adhesive agent is poured between the banks, to adhere the optical pickup case and the optical device.

Abstract: A lens driving device includes a lens holder for holding a lens, a supporter portion for supporting the lens holder in a movable manner, a drive portion for driving the lens holder, and an elastic portion for supplying the lens holder with a force in a predetermined direction. The supporter portion includes a shaft engaging with a bearing of the lens holder, and the force in a predetermined direction includes a force in a direction perpendicular to the shaft and a force in a direction to rotate the lens holder about the shaft.

Abstract: Provided are an objective lens driving unit that maintains the electrical connection between suspension wires and winding bosses. The objective lens driving unit includes a plurality of winding bosses disposed at a side of the frame, each having a projection formed at its end and extending in a direction in which a suspension wire extends.

Abstract: Provided is an objective lens including a diffraction portion provided on a laser beam incident plane or output plane. The diffraction portion includes first second, and third diffraction regions, wherein first laser beams corresponding to a first optical disc having a first transmissive layer are condensed on a data recording portion of the first optical disc, second laser beams corresponding to a second optical disc having a second transmissive layer thicker than the first transmissive layer are condensed on a data recording portion of the second optical disc, and third laser beams corresponding to a third optical disc having a third transmissive layer thicker than the second transmissive layer are condensed on a data recording portion of the third optical disc. An evaluation parameter calculated on the basis of an in-plane efficiency distribution function has a value corresponding to a symbol error rate that is less than a predetermined value.