Abstract: A method producing a refractive or diffractive optical device, including: production, in a first layer, of at least one inclined general profile approximated by a staircase profile including plural stairsteps; production of the profile including: forming buffer patterns on the first layer and at least one sequence including: forming masking patterns, so each masking pattern includes at least one edge situated above a buffer pattern and covers at least one area of the first layer not masked by the buffer patterns, the forming the masking patterns also defining, for the first layer, plural free areas not masked by the masking patterns or by the buffer patterns; etching the free areas to form trenches in the first layer. The production of the profile also includes: removing the masking patterns, removing the buffer patterns revealing walls previously covered by the buffer patterns, and then an isotropic etching to remove the walls.

Abstract: An objective lens (101) is configured to converge laser light of a first wavelength ?1 (390 [nm]??1?430 [nm]), laser light of a second wavelength ?2 (630 [nm]??2?680 [nm]), and laser light of a third wavelength ?3 (750 [nm]??3?810 [nm]) on an information recording surface of a first information recording medium, an information recording surface of a second information recording medium, and an information recording surface of a third information recording medium, and is configured such that the distance from a convergent point of normal diffracted order light, to a virtual collecting point formed by virtual diffracted order light between the convergent point of normal diffracted order light and a collecting point of unwanted diffracted order light is twice or more of the pull-in range of a focus error signal to be obtained in recording or reproducing information with respect to the third information recording medium.

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: Provided are an organic-inorganic composite resin composition and an organic-inorganic composite resin material made of a cured product thereof, containing at least an organic compound having a polymerizable functional group, metal oxide fine particles, and a polymerization initiator. The cured product obtained by curing the organic-inorganic composite resin composition through application of an active energy has a refractive index nd of 1.61 or more and 1.65 or less, Abbe's number ?d of 13 or more and 20 or less, and an anomalous dispersion characteristic ?g,F of 0.42 or more and 0.54 or less. Further provided is an optical element comprising a transparent substrate and the organic-inorganic composite resin material formed on the transparent substrate.

Abstract: Films for optical use, articles containing such films, methods for making such films, and systems that utilize such films, are disclosed.

Abstract: An Al film is formed so that film forming particles are incident at normal incidence to grating wall surfaces of a diffraction grating having multiple grating portions and are incident at oblique incidence to optical effective surfaces. After that, oxidation treatment is performed from a direction to be incident at normal incidence to the optical effective surface so that the Al layer on the optical effective surface is changed to Al2O3 layer. Hence, in the diffraction grating having the multiple grating portions, the Al2O3 layer is formed on the optical effective surface for transmitting light, and the Al layer is formed on the grating wall surfaces as a light shielding layer. Thus, flare of the diffractive optical element can be suppressed.

Abstract: An element includes a first resin layer and a second resin layer disposed between a first glass lens substrate and a second glass lens substrate, a boundary surface between the first resin layer and the second resin layer having a diffraction grating shape including a plurality of inclined surfaces and wall surfaces. The second resin layer is composed of a fluororesin in which fine metal oxide particles are dispersed. Since a refractive index distribution easily occurs in this material during curing by application of ultraviolet light, by applying ultraviolet light substantially perpendicular to the inclined surfaces of the diffraction grating shape, a refractive index distribution is formed in the thickness direction perpendicularly to the inclined surfaces.

Abstract: A diffractive light outcoupling unit for forming a part of a directive light outcoupling system of a lighting device including a plurality of diffractive outcoupling units. The diffractive light outcoupling units each include a carrier element for accommodating a diffractive surface relief pattern, and a diffractive surface relief pattern including a plurality of consecutive diffractive surface relief forms defined on a surface area of the carrier element arranged to couple light incident on the diffractive surface relief pattern outside the carrier element via interaction involving at least two surface relief forms of the plurality of surface relief forms of the diffractive surface relief pattern so as to enhance the directivity of the coupled light. A diffractive light outcoupling system includes a plurality of diffractive light outcoupling units. A lightguide includes the outcoupling system.

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: A lens in accordance with the present invention includes an switchable cell consisting of optical substrate with diffraction surface, elastic film in contact with the diffraction surface of the substrate, optical fluid that fills the space between the film and diffraction surface and the mean to transfer the optical fluid in and out of the space between the film and diffraction surface. The refractive index of the optical fluid matches the refractive index of the optical substrate. The switchable cell changes focus positions between refractive focus in relaxed state when the pressure at both sides of the film is the same and diffraction focus when the optical fluid is transported from the space between the film and optical substrate for the film to largely conform to the diffraction surface shape of the optical substrate.

Abstract: Provided is an immersion diffraction element that prevents decrease of diffraction efficiency thereof so as to satisfy optical performance. A reflection type diffraction element is made of a material transmitting a light, beam having a predetermined wavelength. An echelle diffraction grating covered with a reflecting film that prevents transmission of the light beam is formed on one surface of the material. A diffraction grating is formed off in a repeated manner, a blazed surface facing incident light and a non-blazed surface connecting the blazed surface to a neighboring blazed surface. An angle formed between the blazed surface and the non-blazed surface is an acute angle. A defect generated at a grating vertex of the blazed surface fails in a shadow of the neighboring blazed surface so as to prevent the incident light from becoming scattered light due to the defect portion.

Abstract: A diffractive optical element includes: a body being composed of a first optical material and having a diffraction grating on the surface thereof; and an optical adjustment layer being composed of a second optical material and provided on the body so as to cover the diffraction grating. An envelope passing through the edge of the diffraction grating presents a curved surface, and the optical adjustment layer has a uniform thickness along the normal direction from the envelope.

Abstract: A color sequential illumination device including in series: first and second light sources; a condenser lens; and a grating device. The grating device includes at least one Bragg grating. The condenser lens directs light from the first and second sources into the grating device at first and second incidence angles respectively. The grating device diffracts light from the first and second sources into a common direction. Desirably, the Bragg gratings are Electrically Switchable Bragg Gratings. In one embodiment the light sources are Light Emitting Diodes. Alternatively lasers may be used.

Abstract: A lens including: a central refracting portion and a peripheral portion configured to support the lens in a lens mount wherein the peripheral portion has a surface including at least one out-coupling element configured to couple light out of the lens.

Abstract: A method for manufacturing a blazed diffraction grating made of a crystalline material comprising zinc selenide (ZnSe) or zinc sulfide (ZnS) includes forming the blazed diffraction grating by forming a plurality of grating grooves on a machined surface of a workpiece by machining, wherein the grating grooves are formed so that a surface comprising a (110) plane is arranged to receive the most incident light among the surfaces that constitute each grating, where (110) describes a crystal orientation of the crystalline material.

Abstract: A method for manufacturing a blazed diffraction grating made of a crystalline material comprising gallium phosphide (GaP) or gallium arsenide (GaAs) includes forming the blazed diffraction grating by forming a plurality of grating grooves on a machined surface of a workpiece by machining, wherein the grating grooves are formed so that a surface comprising a (110) plane is arranged to receive the most incident light among the surfaces that constitute each grating, where (110) describes a crystal orientation of the crystalline material.

Abstract: A diffractive optical element includes a first diffractive grating including a first grating surface and a first grating wall surface, a light shielding member disposed on the first grating wall surface, and a second diffractive grating including a second grating surface and a second grating wall surface, disposed so that the second grating surface contacts the first grating surface and the second grating wall surface contacts the light shielding member. An extinction coefficient k of a material that constitutes the light shielding member meets the expression of 0.001<k<0.5.

Abstract: There is provided a diffractive multifocal lens, wherein a diffraction phase structure of a diffraction pattern has a structure expressed by the following formula: ? ? ( ? ) = { p 1 ? ? , 0 ? ? < w p 2 ? ( ? - 0.5 ) - q ? ? ? , w ? ? < 1 - w p 1 ? ( ? - 1 ) , 1 - w ? ? ? 1 ( 1 ) wherein ? indicates a position in a radial direction of the lens in one period of the diffraction pattern, and ?(?) indicates a value (radian) of a phase shift amount of light passing through the position of ? from the phase of light passing through a reference plane.

Abstract: Certain exemplary embodiments can provide a system, machine, device, manufacture, circuit, composition of matter, and/or user interface adapted for and/or resulting from, and/or a method and/or machine-readable medium comprising machine-implementable instructions for, activities that can comprise and/or relate to, switch a diffractive first electro-active lens from a first power state corresponding to a first optical power to a second power state corresponding to a second optical power that differs from said first optical power.

Abstract: An ophthalmic lens for providing a plurality of foci includes an optic having an anterior surface, a posterior surface, and an optical axis. The ophthalmic lens has a first region and a second region. The first region has a first refractive optical power and includes a first base curvature having a finite radius of curvature and a first phase plate having at least one diffraction order with a diffractive optical power. The first region is configured for forming a first focus and a second focus. The second region has a second refractive optical power and includes a second base curvature having a finite second radius of curvature that is different from the first radius of curvature and a second phase plate having at least one diffraction order with a diffractive optical power.

Abstract: A diffractive MEMS device has an in-plane binary reflective diffraction pattern formed in an outer surface of a tiltable platform. The binary reflective diffraction pattern includes rectangular or trapezoidal ridges and valleys, or grooves, of a same depth. The binary reflective diffractive pattern has a high diffraction efficiency even though the surfaces of the “grooves” or “ridges” are not perpendicular to the incoming optical beam. The diffractive pattern is supported by a pair of torsional hinges and is tiltable by an electrostatic actuator. The electrostatic actuator can include at least one side electrode for linearization of dependence of tilt angle on the voltage applied to the actuator.

Abstract: An optical imaging system includes a first diffractive optical element that receives a multi-wavelength beam of light and separates the received beam of light into diffractive orders. The optical imaging system also includes a second diffractive optical element that includes panels displaced along the second diffractive element in at least one direction, where each panel is positioned to receive and pass the multi-wavelength beam of one of the diffractive orders. A refractive optical element is positioned to receive multi-wavelength beams of the diffractive orders that pass through the second diffractive element, and an optical lens that receives the multi-wavelength beams of the diffractive orders that pass through the refractive element and focuses each of the multi-wavelength beams of the diffractive orders to a different location on an image plane at the same time.

Abstract: A hybrid diffraction grating, a mold used to produce the hybrid diffraction grating, and their manufacturing methods are described. In one aspect, a hybrid diffraction grating comprises a grating main body and a reflective layer. The grating main body comprises numerous diffraction structures. When viewed along a top-view direction, the numerous diffraction structures are arranged in a pattern defined by a profile. The profile determines various blaze angles of the numerous diffraction structures. The reflective layer, disposed on the diffraction structures, exhibits characteristics of the numerous diffraction structures.

Abstract: A diffractive optical element made by adhering a first diffractive grating and a second diffractive grating to each other, each of which has a blazed structure. At least one of the first and second diffractive gratings is made of a material having a refractive index distribution in a plane normal direction, and the predetermined expressions are satisfied for a wavelength ? in a visible wavelength range.

Abstract: An optical element including: a first light transmitting layer having a first sawtooth blazed surface, the first light transmitting layer including a plurality of first light-transmitting slopes defining a first blaze angle ?; and a second light transmitting layer having a second sawtooth blazed surface including a plurality of second light-transmitting slopes defining a second blaze angle ?, the second light transmitting layer being in contact with the first sawtooth blazed surface of the first light transmitting layer. A tilting direction of the first light-transmitting slope and a tilting direction of the second light-transmitting slope are opposite.

Abstract: A diffractive lens 11 that includes: a lens base 18, which has a second surface 13 with first and second groups of diffraction grating portions 20 and 21; and a protective coating 17, which is arranged on the first group of diffraction grating portions 20. The first group of diffraction grating portions 20 has a first group of diffraction steps and the second group of diffraction grating portions 21 has a second group of diffraction steps, which is lower in height than the first group of diffraction steps. One of the respective materials of the base 18 and the protective coating 17 has a higher refractive index and a greater Abbe number than the other material. And the second group of diffraction steps is not covered with the protective coating 17.

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 optical arrangement includes a light source which emits coherent light of a wavelength ?, and a diffraction grating which has a multiplicity of diffraction structures which follow one another periodically at the spacing of a grating period d and are arranged along a base surface, the individual diffraction structures respectively having a blaze flank and an antiblaze flank, the blaze flanks being arranged at an angle ? and the antiblaze flanks being arranged at an angle ? to the base surface, and respectively neighbouring blaze and antiblaze flanks enclosing an apex angle ?, and an incident light beam being arranged at a Littrow angle ?L relative to a grating normal of the diffraction grating.

Abstract: Planar reflective devices that operate as reflective blazed diffraction gratings are disclosed. In one aspect, a reflective device includes a substrate with a planar surface, and a planar, high-contrast, sub-wavelength grating disposed on the surface. The grating is divided into a number of regions that each reflect incident light of a particular wavelength and with a particular angle of incidence into a single diffraction order and associated diffraction angle.

Abstract: An Echelle diffraction grating has a Littrow configuration. Each grating includes a resin layer made of light curing resin and having a thickness between 2 ?m and 10 ?m, and a reflective coating layer formed on the resin layer, having a thickness between 120 nm and 500 nm, and made of aluminum. An apex angle between a blazed surface and a counter surface is between 85° and 90°. A first blaze angle is an angle that maximizes diffraction efficiency of a set blazed order for incident light of a wavelength of 193.3 nm. A blaze angle has an initial value of a second blaze angle smaller than the first blaze angle. 0.25°?bd?ba?1.2° is satisfied where bd denotes the first blaze angle and ba denotes the second blaze angle.

Abstract: A manufacturing method for an excimer laser that includes a reflective Echelle diffraction grating includes obtaining information of a wavelength of a light source, a blazed order, a repetitive pitch of the grating, a material of the grating, and a predefined orientation ratio B/A that is a ratio between that a diffraction efficiency A of the blazed order and a diffraction efficiency Bb of an order lower by one order than the blazed order, and determining an initial value of a blaze angle based upon these pieces of information.

Abstract: Provided are an objective lens with enhanced transmittance and an optical pickup apparatus which can record and/or reproduce information properly for three kinds of discs with different recording densities, even if a single lens is used as the objective lens. When all the expressions (1) to (3) are satisfied, excellent aberration characteristics can be obtained for the three kinds of discs: ?0.02?m1?0.02 (1); 0?(WD1?WD2)?1.57 m2+0.123 or 1.57 m2+0.24?(WD1?WD2)?0.7 (2); and 0?(WD1?WD3)?1.79 m3+0.333 or 1.66 m3+0.508?(WD1?WD3)?0.7 (3).

Abstract: An optical member includes: a total reflection mirror 14 including a reflection surface 14a for reflecting a laser beam 16; a filter 13 including a partially transmissive surface 13a for passing therethrough a part of the laser beam 16 and reflecting the remaining part of the laser beam, the partially transmissive surface 13a being located so as to be opposed to the reflection surface 14a; and a diffraction grating 18 into which the laser beam 16 enters, for diffracting the incident laser beam 16 to enter the total reflection mirror 14 or the partially transmissive filter 13.

Abstract: The present invention provides improved ophthalmic lenses and methods for their design and use. Monofocal and multifocal diffractive ophthalmic lenses having reduced light scatter and/or improved light energy distribution properties are provided. These properties are provided by the diffractive profiles of the invention, often having subtly shaped echelettes with appropriately curving profiles. Light scatter may be generated by the sharp corners associated with vertical steps between adjacent conventional diffractive echelettes. Smooth diffractive profiles of the invention reduce light scatter. Light energy directed towards non-viewing diffractive orders may have a unwanted effects on vision quality. Diffractive profiles of the invention may limit the light energy in certain, selected orders, thereby improving viewing quality and mitigating unwanted effects such as dysphotopsia.

Abstract: An optical de-multiplexer (de-MUX) that includes an optical device that images and diffracts an optical signal using a reflective geometry is described, where a free spectral range (FSR) of the optical device associated with a given diffraction order abuts FSRs associated with adjacent diffraction orders. Moreover, the channel spacings within diffraction orders and between adjacent diffraction orders are equal to the predefined channel spacing associated with the optical signal. As a consequence, the optical device has a comb-filter output spectrum, which reduces a tuning energy of the optical device by eliminating spectral gaps between diffraction orders of the optical device.

Abstract: An objective optical system for an optical information recording/reproducing apparatus, at least one surface of the objective optical system being configured to be a phase shift surface having a phase shift structure, wherein: the phase shift surface has a first area contributing to converging first, second and third light beams onto recording surfaces of first, second and third optical discs, respectively; in the first area, the phase shift surface has at least two types of phase shift structures including a first phase shift structure having first steps and a second phase shift structure having second steps; the phase shift surface has a plurality of combinations of annular zones which satisfy a condition: 0.95<P1/P2<1.05??(1), and the phase shift surface satisfies a following condition: ?3.00<??1/??2<?0.10??(2).

Abstract: A diffraction grating structure having ultra-high density of grooves comprises an echellette substrate having periodically repeating recessed features, and a multi-layer stack of materials disposed on the echellette substrate. The surface of the diffraction grating is planarized, such that layers of the multi-layer stack form a plurality of lines disposed on the planarized surface of the structure in a periodical fashion, wherein lines having a first property alternate with lines having a dissimilar property on the surface of the substrate. For example, in one embodiment, lines comprising high-Z and low-Z materials alternate on the planarized surface providing a structure that is suitable as a diffraction grating for EUV and soft X-rays. In some embodiments, line density of between about 10,000 lines/mm to about 100,000 lines/mm is provided.

Abstract: An optical pickup device divides signal light so as to detect the divided signal light. For example, a photodetector can include a region “A” and another region “B.” Among diffracted light diffracted from a track on an optical disc, only zeroth-order diffraction light enters region “A”, whereas the zeroth-order diffraction light, + first-order diffraction light, and ? first-order diffraction light enter region “B”. A focusing error signal from the photodetector is produced based upon a signal detected by the photodetector, whereas a tracking error signal is produced based upon signals detected from the regions “A” and “B.” A stable focusing error signal and a stable tracking error signal can be detected with respect to a dual layer optical disc, or a multi layer optical disc.

Abstract: Methods of forming microelectronic structures are described. Embodiments of those methods may include forming a photomask on a (110) silicon wafer substrate, wherein the photomask comprises a periodic array of parallelogram openings, and then performing a timed wet etch on the (110) silicon wafer substrate to form a diffraction grating structure that is etched into the (110) silicon wafer substrate.

Abstract: An element includes a first resin layer and a second resin layer disposed between a first glass lens substrate and a second glass lens substrate, a boundary surface between the first resin layer and the second resin layer having a diffraction grating shape including a plurality of inclined surfaces and wall surfaces. The second resin layer is composed of a fluororesin in which fine metal oxide particles are dispersed. Since a refractive index distribution easily occurs in this material during curing by application of ultraviolet light, by applying ultraviolet light substantially perpendicular to the inclined surfaces of the diffraction grating shape, a refractive index distribution is formed in the thickness direction perpendicularly to the inclined surfaces.

Abstract: A method for manufacturing a diffraction grating having a plurality of grating grooves that extends in parallel in a direction includes a first cutting processing step of moving, in the direction, a work and a cutting tool having a first blade and a second blade relatively to each other, and of forming a first surface of the grating groove in the work through cutting processing using the first blade of the cutting tool, and a second cutting step of moving, in the direction, the work and the cutting tool relatively to each other after the first cutting processing step, so that the first blade does not contact the first surface formed by the first cutting processing step, and of forming a second surface of the grating groove in the work through cutting processing using the second blade of the cutting tool.

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: The present invention provides improved ophthalmic lenses and methods for their design and use. Monofocal and multifocal diffractive ophthalmic lenses having reduced light scatter, improved light energy distribution properties, and/or other improvements in optical performance are provided. These properties are provided, at least in part, by the diffractive profiles of the invention, often having subtlety shaped echelettes with appropriately curving profiles. Smooth diffractive profiles may be used reduce light scatter. Diffractive profiles may be configured to limit the light energy in certain selected orders, thereby improving viewing quality and mitigating unwanted effects such as dysphotopsia. Diffractive profiles of may additionally or alternatively vary the light energy distributed between individual echelettes, providing additional advantages in various viewing situations.

Abstract: Provided is an objective lens used in an optical pickup that performs recording and/or reproducing of information signals on three different types of optical discs using different wavelengths. The objective lens is configured to collect light beams with the at least three wavelengths ?1, ?2, and ?3, which satisfy a relationship of ?1<?2<?3, on signal recording surfaces of compatible optical discs corresponding to the respective wavelengths. The objective lens includes: a diffractive portion that has a predetermined diffraction structure formed on an incident side surface. The diffractive portion has a first region that is provided in an innermost peripheral portion so as to diffract the light beams, a second region that is provided outside the first region so as to diffract the light beams, and a third region that is provided outside the second region.

Abstract: The invention relates to a transparent substrate comprising at its surface a grating of lines of at least 200 light-diffusing elements, said elements being separated by domains with a different refractive index from that of the elements, the distance d between centers of gravity of neighboring elements varying in a non-monotonic manner from one edge of the grating to the other, so that for any group of 50 successive elements, the distance d between the centers of gravity of neighboring elements of said group is at least once greater than and at least once less than the mean distance dm of distances d between centers of gravity of neighboring elements of said group, dm lying between 75 nm and 200 ?m. This substrate is transparent in direct vision and redirects the light while diffusing it without iridescence in a daylighting application.

Abstract: A wavelength selection filter selectively resonating and reflecting light of a given wavelength contained in incident light, includes a substrate having a rectangular waveform concave and convex structure which is formed on a plane on which the incident light falls incident, the concave and convex structure including convex portions and concave portions which are arranged in one axial direction and a multilayer structure including a first layer and a second layer respectively coating one and the other one of side surfaces, in the one axial direction, of each of convex portions of the concave and convex structure. A refractive index of the first layer and a refractive index of the second layer are both higher than a refractive index of the substrate.

Abstract: An optical element which can be shared by three wavelengths for BD, DVD, and CD and which is easily manufactured is provided. An objective lens system includes an optical element 1A and a converging lens element 1B. A first surface of the optical element 1A on an incident side is concentrically divided into a region 11 including a rotational symmetry axis, a region 12, and a region 13. On the optical element 1A, a periodic stair-like diffraction structure and a periodic sawtooth-like diffraction structure are provided. A second surface of the optical element 1A is divided into a region 21 including a rotational symmetry axis, a region 22, and a region 23. On the region 21, a sawtooth-like diffraction structure is provided. The converging lens element 1B converges light having passed through the optical element 1A, to form a spot on an information recording surface of an optical disc.

Abstract: A multifocal lens device is disclosed. The device comprises a lens body being formed with a plurality of concentric annular zones separated by slanted steps. The concentric zones effect both diffraction and refraction of incident light, while the steps are substantially devoid of any diffractive or refractive power.

Abstract: Provided is an optical pickup device which can properly record and/or reproduce information on and/or from three types of discs having different recording densities and is simple in configuration and low cost. An objective lens is also provided. On the optical surface of the objective lens, an optical path difference giving structure is formed. Out of diffracted light generated when a first luminous flux enters the structure, second order diffracted light has the maximum diffraction volume. Out of diffracted light generated when a second luminous flux enters the structure, zero order diffracted light has the maximum diffraction volume. Out of diffracted light generated when a third luminous flux enters the structure, the minus first order diffracted light has the maximum diffraction volume.

Abstract: A diffraction grating lens of the present invention includes a lens base 51 having a surface 51b obtained by providing a diffraction grating 52 on a base shape. The diffraction grating 52 includes a plurality of zones 61A and 61B and a plurality of first diffraction steps 65A and second diffraction steps 65B located between the plurality of zones; the lens base is made of a first material whose refractive index is n1(?) at a working wavelength ?; and the first diffraction steps 65A and the second diffraction steps 65B have substantially the same height d. The height d satisfies Expression (1) below, where m denotes a diffraction order. A first surface 66A on which tips 63A of the first diffraction steps 65A are located and a second surface 66B on which tips 63B of the second diffraction steps 65B are located are at different positions from each other on an optical axis 53.