Abstract: There is described a process for the production of a multi-layer body (100) having a partially shaped first layer (3m), wherein it is provided that in the process a diffractive first relief structure (4) with a high depth-to-width ratio of the individual structure elements, in particular with a depth-to-width ratio of >0.3, is shaped in a first region (5) of a replication layer (3) of the multi-layer body (100) and the first layer (3m) is applied to the replication layer (3) in the first region (5) and in a second region (4, 6) in which the relief structure is not shaped in the replication layer (3), with a constant surface density, and the first layer (3m) is partially removed in a manner determined by the first relief structure so that the first layer (3m) is partially removed in the first region (5) or in the second region (4, 6) but not in the second region (4, 6) or in the first region (5) respectively.

Abstract: An apparatus for measuring an image of a pattern to be formed on a semiconductor by scanning the pattern using a scanner, the apparatus including an EUV mask including the pattern, a zoneplate lens on a first side of the EUV mask and adapted to focus EUV light on a portion of the EUV mask at a same angle as an angle at which the scanner will be disposed with respect to a normal line of the EUV mask, and a detector arranged on another side of the EUV mask and adapted to sense energy of the EUV light from the EUV mask, wherein NAzoneplate=NAscanner/n and NAdetector=NAscanner/n*?, where NAzoneplate denotes a NA of the zoneplate lens, NAdetector denotes a NA of the detector, and NAscanner denotes a NA of the scanner, ? denotes an off-axis degree of the scanner, and n denotes a reduction magnification of the scanner.

Abstract: A diffractive optical element 10 is constituted by sandwiching and closely bonding first and second optical element components 13, 14 which have different refractive indices and are adhered via a relief pattern 20, between third and fourth optical element components 11, 12.

Abstract: A disclosed device for optically scanning a target surface includes a light source unit configured to emit a light beam; a light intensity detecting unit; a coupling unit configured to substantially collimate the emitted light beam; a beam limiting unit configured to limit the amount of the collimated light beam; a beam splitting unit configured to split the beam limited light beam and thereby to cause a first portion of the beam limited light beam to enter the light intensity detecting unit, wherein the light intensity detecting unit is configured to detect the intensity of the first portion of the beam limited light beam; and a beam deflecting unit configured to deflect a second portion of the split light beam toward the target surface. In the disclosed device, the beam limiting unit and the beam splitting unit are integrated as a single unitary structure and positioned between the coupling unit and the light deflecting unit.

Abstract: A multilayer wire-grid polarizer for polarizing light includes a stack of thin film layers disposed over a substrate, including a wire-grid array of elongated metal elements having lengths longer than a wavelength of the light and a period less than half the wavelength of the light. One of the layers can include a thin film layer with a refractive index greater than a refractive index of the substrate. One of the thin film layers can include a dielectric array of non-metal elements.

Abstract: In a transmission grating as a dispersive element, diffraction efficiency is enhanced and manufacturing costs are considerably reduced. A dispersive element includes resin members for forming a diffraction grating, being composed of a plurality of diffraction grating members having a cross-sectional shape respectively surrounded by two straight lines such as a triangular shape, and metal members as light-shielding members each being formed on corresponding one of the diffraction grating members at one side of the diffraction grating member along any of the straight line and the curved line of the cross-sectional shape of the diffraction grating member formed by the resin member. The metal members are configured to reduce zero-order transmitted light with respect to incident light, and to enhance diffraction efficiency of first-order transmitted light.

Abstract: A diffractive optical element according to the present invention includes: a body 1 being composed of a first optical material containing a first resin, and having a diffraction grating 2 on a surface thereof; and an optical adjustment layer 3 being composed of a second optical material containing a second resin, and provided on the body 1 so as to cover the diffraction grating 2. The first optical material has a refractive index which is smaller than a refractive index of the second optical material; the refractive index of the first optical material has a wavelength dispersion which is greater than a wavelength dispersion of the refractive index of the second optical material; and a difference in solubility parameter between the first resin and the second resin is no less than 0.8 [cal/cm3]1/2 and no more than 2.5 [cal/cm3]1/2.

Abstract: Microparticles 8 includes an optical substrate 10 having at least one diffraction grating 12 disposed therein. The grating 12 having a plurality of colocated pitches ? which represent a unique identification digital code that is detected when illuminated by incident light 24. The incident light 24 may be directed transversely from the side of the substrate 10 with a narrow band (single wavelength) or multiple wavelength source, in which case the code is represented by a spatial distribution of light or a wavelength spectrum, respectively. The code may be digital binary or may be other numerical bases. The micro-particles 8 can provide a large number of unique codes, e.g., greater than 67 million codes, and can withstand harsh environments. The micro-particles 8 are functionalized by coating them with a material/substance of interest, which are then used to perform multiplexed experiments involving chemical processes, e.g., DNA testing and combinatorial chemistry.

Abstract: A polarization device includes an optical stack with a diffraction grating and a wire grid polarizer with one disposed over the other. The wire grid polarizer includes an array of elongated, parallel conductive wires in accordance with PWGP<?/2 where PWGP is the period of the wires and ? is the wavelength of the light. The diffraction grating includes an array of elongated parallel dielectric ribs in accordance with PDG>?/2 where PDG is the period of the ribs.

Abstract: A diffractive optical element includes a first optical part and a second optical part bonded to each other with a bonded surface therebetween configured as a diffraction surface. In this diffractive optical element, the diffraction order of diffracted light with the largest quantity of light out of diffracted light for one of a plurality of kinds of laser beams obtained on the diffraction surface is different from the diffraction order for at least another laser beam.

Abstract: A sub-wavelength anti-reflective diffractive structure is incorporated with a base diffractive structure having a small period to form a high efficiency diffractive structure. In the high efficiency diffractive structure, the anti-reflective structure and/or the base diffractive structure are altered from their ideal solo structure to provide both the desired performance and minimize reflections.

Abstract: A multilayer dielectric transmission grating is made by coating a substrate with an antireflective (AR) coating and placing a dielectric grating on the AR coating. This grating is designed to transmit the maximum amount of light transmitted through the optic into the ?1 order. Both the grating and the AR coating are designed to user specifications based on the desired incidence angle and wavelength range. The AR coating and grating act in concert to maximize the transmitted diffraction efficiency.

Abstract: A method of producing a personalized security document or article includes providing a substrate which is transparent at least to visible light. A diffractive optical microstructure is formed in a substantially opaque layer disposed on a surface of the substrate. The diffractive structure comprises a plurality of apertures formed in the opaque layer, such that when the structure is suitably illuminated, for example by a beam of collimated light, a projected image is generated which is unique to a particular individual. Also, personalized security documents or articles made in accordance with the method.

Abstract: The specification and drawings present a new apparatus and method for providing color separation in an exit pupil expander system that uses a plurality of diffractive elements for expanding the exit pupil of a display in an electronic device for viewing by introducing a selectively absorbing area or areas in the exit pupil expanders.

Abstract: The invention concerns a multi-layer body (7) having a carrier substrate (750) and a transparent layer (720) at least partially arranged in a window (70) or in a transparent region of the carrier substrate (750). The transparent layer (720) has at least a first subregion (71a) and a second subregion (71b) with a varying refractive index, which are arranged in mutually juxtaposed relationship in the layer plane defined by the transparent layer (720), and are at least partially arranged in the window (70) or in the transparent region of the carrier substrate (750). Each of the subregions (71a, 71b) has a plurality of periodically arranged nodes which form an optical-action element and which are formed by a refractive index variation and which are arranged in substantially mutually parallel planes. The planes in the at least first subregion (71a) are not parallel to the planes in the at least second subregion (71b).

Abstract: The diffractive optical element is constituted by a glass material and a resin material whose dn/dT representing refractive index variation with temperature is larger than that of the glass material, the resin material being in close contact with or facing the glass material, and a diffractive grating formed at a close contact portion or a facing portion between the glass material and the resin material. The resin material is a mixture material of (a) a resin base material, (b) first fine particles formed of a first material whose dn/dT is equal to or higher than ?1×10?5(/° C.) and (c) second fine particles formed of a second material whose Abbe constant is lower than that of the glass material. The diffractive optical element can maintain high diffraction efficiency in a wide wavelength region even if temperature changes, without generating unnecessary diffracted light.

Abstract: A diffractive optical element that can be molded readily, an imaging apparatus incorporating the diffractive optical element, and a method for manufacturing the diffractive optical element are provided. A diffractive optical element (10) includes a substrate (11) that is made of a first material containing a resin and has a surface (11a, 11b) on which a diffraction grating pattern (12a, 12b) is formed, and a coating film (13a, 13b) that is made of a second material containing a resin and is disposed so as to be in contact with a portion of the diffraction grating pattern (12a, 12b), and at least one material selected from the first material and the second material is a composite material containing inorganic particles.

Abstract: A wavelength filter, includes a grating in which a first portion extends in X direction on a substrate surface and a second portion extends in the X direction along the first portion and are alternately arranged in Y direction perpendicular to the X direction on the substrate surface at a constant cycle shorter than a wavelength of light to be used. A cross-sectional figure of respective first portions in the Y direction and perpendicular to the substrate surface is provided with at least one protruding portion so as to have the width in the Y direction wider than neighboring portions. Plural waveguide layers parallel to the substrate surface are divided by regions parallel to the substrate surface. Wavelength bands of light reflected from the plural waveguide layers shift while overlapping with each other to reflect a wavelength band broader than that reflected from a single waveguide layer.

Abstract: An optical element, includes: a diffractive functional layer which diffracts at least part of incident light; and a grid formed on a first surface of the diffractive functional layer, the grid including a plurality of fine wires and having a polarization separation function; wherein the optical element reflects a part of the incident light while transmitting another part of the incident light, the first surface of the diffractive functional layer including: a plurality of first regions; a plurality of second regions, a height thereof relative to a second surface of the diffractive functional layer being different from that of the first regions, the second surface being an opposite surface to the first surface; and a step provided at a border between the first regions and the second regions.

Abstract: The diffractive optical element includes two diffraction gratings made of different materials and being in contact with each other at their grating surfaces. The materials satisfy the following conditions, and the second material is obtained by mixing a resin material with a particulate material satisfying the following conditions: nd1?1.48, ?d1?40, (?1.665E?07×?d13+5.213E?05×?d12?5.656E?03×?d1+0.675)??g,F1?(?1.665E?07×?d13+5.213E?05×?d12?5.656E?03×?d1+0.825), (?1.687E?07×?d13+5.702E?05×?d12?6.603E?03×?d1+1.400)??g,d1?(?1.687E?07×?d13+5.702E?05×?d12?6.603E?03×?d1+1.580), nd2?1.6, ?d2?30, ?g,F2?(?1.665E?07×?d23+5.213E?05×?d22?5.656E?03×?d2+0.675), ?g,d2?(?1.687E?07×?d23+5.702E?05×?d22?6.603E?03×?d2+1.400), nd1?nd2>0, ndb2?1.70, ?db2?20. The element achieves a high diffraction efficiency in a specific diffraction order over a wide wavelength range.

Abstract: A diffractive optical element includes a plurality of layered diffraction gratings which includes two diffraction gratings made of materials having different dispersive powers. The plurality of diffraction gratings includes a first diffraction grating having a plurality of grating portions provided on a first base surface, and a second diffraction grating having a plurality of grating portions which are provided on a second base surface. In the second diffraction grating, a height of the grating portion of the central circular zone from the second base surface is greater than a height of the grating portion of the peripheral circular zone from the second base surface.

Abstract: A double-layer grating structure for efficient retroreflection of incident radiation and efficient transmission of the undiffracted incident radiation is disclosed. The grating is constructed of two spaced-apart layers of periodically arranged metal stripes, wherein the stripes in one layer overlap with gaps between the stripes in the second layer. The layers are encapsulated with a dielectric material. A method for producing such grating is also described.

Abstract: A molded product having a phase separation structure formed by photopolymerization of a photopomerizable composition and imparting a sharp diffraction spot at a high diffraction efficiency, and a method for manufacturing same are provided. The molded product (1) comprises a matrix (2) and a multiple columnar structures (3) disposed within the matrix (2) and having an index of refraction different from the matrix (2), wherein the half width of a diffraction spot is 0.6° or less and diffraction efficiency is 10% or greater in an angular spectrum obtained by irradiation with a laser beam having an intensity distribution of standard normal distribution and a half width of the intensity distribution of 0.5°. The multiple columnar structures (3) are oriented in approximately the same direction, and are aligned in a regular lattice on a plane perpendicular to said orientation direction.

Abstract: A transmissive diffraction grating includes a substrate and a plurality of ridges provided in a mutually parallel manner at constant periodicity p on the substrate. The ridges include a first layer, a second layer (refractive index n2: 2.0-2.5), and a third layer with non-continuous refractive indices, arranged in that order from the substrate outward. The first layer adjacent the substrate, in terms of its refractive index, exhibits a difference of 0.1 or less relative to the substrate. The second layer has a higher refractive index than the first layer and third layer and satisfies the following conditions. For a single ridge, the cross-sectional area S of a cross-section of the second layer perpendicular to the longitudinal direction of said ridge is in the range of 0.75p2k1?2/(n2?1)<S<1.20p2k1?2/(n2?1), were, ? is the angle of incidence onto the diffraction grating face, expressed in radian units, and the constant k1 is 1.1. The thickness d2 of the second layer is in the range of 0.

Abstract: Briefly, in accordance with one or more embodiments, an optical relay comprises a partially-reflective-coated Fresnel lens or similar low-profile lens such as a diffractive lens or a holographic lens having a first index of refraction and a filler medium having a second index of refraction and being disposed adjacent to the Fresnel lens. The optical relay enables the optical power of the Fresnel or similar low-profile lens embedded within the two layers to influence a beam that is reflected from the optical relay while allowing transmitted light to experience little or no influence from the embedded lens.

Abstract: An optical structure includes a light transmissive substrate having a surface relief pattern applied thereon, such as a hologram. One or more layers can be patterned corresponding to materials playing the role of absorbers or reflectors on a Fabry-Perot type of optical structure. These materials are applied over portions of the surface relief pattern so as to form alphanumeric characters, bars codes, or pictorial or graphical designs. Additional layers may be applied to the patterned layer of the reflective or absorber materials and exposed portions of the surface relief pattern in order to provide desirable optical effects to the exposed portions of the surface relief pattern. In some embodiments, the optically active coating is a color shifting thin film, or contains color shifting flakes based on Fabry Perot designs.

Abstract: An Si—O containing hydrogenated carbon film as an optical film has a refractive index in a range from at least 1.48 to at most 1.85 for light of 520 nm wavelength and an extinction coefficient of less than 0.15 for light of 248 nm wavelength, wherein the refractive index and the extinction coefficient are decreased with energy beam irradiation. By utilizing such an Si—O containing hydrogenated carbon film, it is possible to provide various types of optical elements and an optical device including the same.

Abstract: A multi-layered diffraction optical element, comprises a transparent substrate, a first layer having a diffraction grating shape at least on one face and comprised of a relatively high refractive index and low dispersion material, and a second layer having a diffraction grating shape at least on one face and comprised of a relatively low refractive index and high dispersion material, wherein the first and second layers are laminated on the transparent substrate so that the respective diffraction grating shapes are mutually opposed to each other with no space therebetween, and, the first layer is comprised of a first organic resin including a first inorganic fine particle, and the second layer is comprised of a second organic resin including a second inorganic fine particle different from the first inorganic fine particle.

Abstract: A film (1) which comprises at least one transparent replicating layer (2) having a diffractive relief structure (3) and a reflective layer, the reflective layer being formed by at least one pigmented lake layer (4), and the film (1, 1?, 1?) showing a latent optically variable effect produced by the diffractive relief structure (3), and the use thereof. The invention furthermore relates to a method for the production of such a film.

Abstract: A diffractive optical element includes: a substrate having a first face and a second face; a diffractive structure section that is formed on the first face of the substrate, shaped in a rectangular form in a cross-sectional view of the diffractive structure section, and having an upper face and a plurality of protuberance portions; and a grid section that is formed of a dielectric material, formed on at least one of the upper face of the diffractive structure section and the second face of the substrate, and including micro protuberance portions that are smaller than each of the protuberance portions.

Abstract: A small shooting lens has high optical performance and is suitable for mass production. To attain this, the shooting lens includes at least three lens groups disposed in order from an object side, wherein an adhesion multiple-layer diffractive optical element is formed on one of surfaces disposed between an object surface and an imaging plane, and a maximum image height Y and an entire length L satisfy 0.1<Y/L<3.0 . . . (1). Thus using the multiple-layer diffractive optical element in the shooting lens makes it possible to improve diffraction efficiency over a wide range and reduce flare. Particularly, the multiple-layer diffractive optical element has a merit that its production and assembling are easy. Further, according to the conditional expression (1), it is possible to realize the downsizing of the shooting lens while also maintaining its imaging quality.

Abstract: An achromatic lens system is provided with a cemented resin lens having positive refractive power constructed by a resin lens L11 having positive refractive power cemented with a resin lens L12 having negative refractive power, and a close-contact multi-layer type diffractive optical element L11E, the diffractive optical element L11E being disposed to an image side of the cemented resin lens, the diffractive optical element L11E being constructed by cementing two diffractive element members DE11, DE12 each made of different optical materials with each other, and the cemented surface thereof being a diffractive optical surface Gf on which grooves of a diffraction grating are formed, there by being lightweight and easily manufactured, capable of excellently correcting chromatic aberration and spherical aberration at the same time.

Abstract: An inorganic, dielectric grid polarizer includes an optical stack with a diffraction grating and an inorganic, dielectric grid polarizer. The inorganic, dielectric grid polarizer includes a stack of film layers with an array of parallel ribs in accordance with PGP<?/2 where PGP is the period of the ribs and ? is the wavelength of the light. The diffraction grating includes an array of elongated parallel dielectric ribs in accordance with PDG>?/2 where PDG is the period of the ribs.

Abstract: A diffractive optical element includes at least a first diffractive element and a second diffractive element. The conditional expression 0.5?D/DS?0.9 is preferably satisfied where DS denotes the summation of the optimum designed groove height of the first diffractive element d1S and that of the second diffractive element d2S, and D denotes the summation of an actual groove height of the first diffractive element d1and that of the second diffractive element d2. At least one of the first diffractive element and the second diffractive element is made of glass. At least one of the first diffractive element and the second diffractive element is made of resin. The optimum designed value of groove heights of the diffractive optical element are determined so as to satisfy a condition for correcting chromatic aberration at both d-line and g-line.

Abstract: The present invention is a diffractive optical element 1 in which mutually different materials make contact with one another via the same diffraction grating groove 30. One of the mutually different materials is a first ultraviolet curing resin 10 and the other of the mutually different materials is a second ultraviolet curing resin 20 that is different from the first ultraviolet curing resin 10.

Abstract: A diffractive optical element includes a plurality of diffraction gratings. A diffraction grating within the plurality of diffraction gratings includes a plurality of grating parts having a curved grating surface and grating tips which connect to define a curved envelope face. The grating surface has a radius of curvature larger than a radius of curvature of the envelope face. In addition, two diffraction gratings within the plurality of diffraction gratings are composed of different materials having different dispersions. Therefore, even when the radius of curvature of the envelope face is small, the degradation of the diffraction efficiency is suppressed.

Abstract: A bilayer transmission diffraction grating having antireflection lines having rectangular cross-section over grating lines having trapezoidal cross-section is described. The process-dependent grating line profile is accounted for by characterizing the grating line profile and performing electromagnetic wave diffraction simulations, whereby a grating duty cycle is selected that results in an improvement of overall diffraction efficiency and/or reducing polarization dependent loss of a diffraction grating having the characterized grating line profile. Grooves in the substrate between the grating lines further improve diffraction efficiency and reduce polarization dependent loss. The entire grating line profile, including the antireflection line, the grating line, and the groove in the substrate between the grating lines, can be defined using a single etch mask, which reduces process and equipment related manufacturing costs.

Abstract: The present invention relates to pigments comprising or consisting of a layer made of a material with an index of refraction that is higher than the index of refraction of the adjacent material by at least 0.25; whereas said layer has a zero-order diffractive micro-structure; whereas said layer acts as an optical waveguide and whereas said layer has a thickness between 50 nm and 500 nm; to processes for its manufacture and to its use. These pigments show a colour effect upon rotation and/or tilting, and it is believed that this colour effect is based on zero-order diffraction.

Abstract: An optical part for a camera comprising a substrate made of a polyolefin plastic and an optical resin layer placed on the substrate, wherein the surface of the substrate is provided with a polar group and the optical resin layer is formed from a resin composition including a fluorene compound having a (meth)acryloyl group.

Abstract: A grating includes an absorptive substrate and a plurality of reflective lines on the absorptive substrate. Each reflective line is formed by a plurality of reflective areas. The reflective areas can be arranged in a regular pattern. The reflective areas are between 70 nm and 120 nm in diameter. The reflective areas can be circular. The reflective areas can have a random height distribution.

Abstract: An identification document having enhanced security and replication deterrence, while providing a simple low cost solution to other verification and authentication technologies. In one implementation, the document is provided with a multi-layer, multi-axis diffractive optical variable image device (DOVID) that is based on specific data or information on the document. The result is that the DOVID is directly tied to data or information that is specific to the document. This DOVID security feature is verifiable by the human eye so that no high levels of technology are necessary to verify authenticity. In addition, this DOVID security feature has enhanced tamper detection.

Abstract: An optical pulse-width modifier structure includes a first diffraction grating and an optically unpowered reversing mirror. An optical path extends between the first diffraction grating and the optically unpowered reversing mirror. A second diffraction grating lies on the optical path between the first diffraction grating and the optically unpowered mirror. A set of optically powered mirrors lies on the optical path between the first diffraction grating and the second diffraction grating. The diffraction gratings and mirrors are positioned such that an input light beam is diffracted from the first diffraction grating, reflected from each of the set of optically powered mirrors, diffracted from the second diffraction grating, reflected from the optically unpowered reversing mirror back to the second diffraction grating, diffracted from the second diffraction grating, reflected from each of the set of optically powered mirrors, and diffracted from the first diffraction grating as an output light beam.

Abstract: A polarizing element usable for two wavelengths in a predetermined wavelength region and having a simple structure. The polarizing element has a two-layer structure in which a grid pattern of a constant period ? having a triangular cross-section is formed on a substrate and a film with a refractive index higher than that of the substrate is deposited on the grid pattern. When first and second wavelengths ?1, ?2 satisfy ?1<?2, ? cos ?0<?1 where ?0 is the angle of incidence on the grid surface.

Abstract: A diffraction grating device includes a substrate with a primary surface having a plurality of grating areas that are periodically arranged with a constant period in a predetermined axis direction, the grating area including a first area and a second area, a diffraction grating structure providing a chirped grating whose pitch monotonically changes along the predetermined axis direction, a core layer that is optically coupled with the diffraction grating structure with a coupling coefficient, a plurality of grating portions including the diffraction grating structure and the core layer, the grating portion including a first portion and second portion that are arranged on the first area and the second area, respectively, of the primary surface and a perturbing layer disposed at the first portion or the second portion. The perturbing layer changes the coupling coefficient between the diffraction grating structure and core layer.

Abstract: Practical diffractive optical elements are made available efficiently and at low-cost. A refractive-index-modulated diffractive optical element includes a transparent DLC (diamond-like carbon) film (2) formed on a transparent substrate (1), with the DLC film (2) containing a diffraction grating having local regions (2a) of a relatively high refractive index and local regions (2) of a relatively low refractive index. The DLC film (2) can readily be deposited by plasma CVD onto the substrate (1), and the high refractive-index regions (2a) within the DLC film can readily be formed by irradiating it with an energy beam (4) such as an ion beam.

Abstract: A multilayer wire-grid polarizer for polarizing light includes a stack of thin film layers disposed over a substrate, including a wire-grid array of elongated metal elements having lengths longer than a wavelength of the light and a period less than half the wavelength of the light. One of the layers can include a thin film layer with a refractive index greater than a refractive index of the substrate. One of the thin film layers can include a dielectric array of non-metal elements.

Abstract: A resin composition includes a binder component having at least one of a monomer and an oligomer of one or more of a fluorine system and a silicone system having a polymerizable functional group in a molecule. The resin composition also includes fine metal oxide particles, and a polymerization initiator. The fine metal oxide particles include particles selected from the group of zinc oxide, indium oxide, tin oxide, antimony oxide, tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), and fluorine-doped tin oxide (FTO).

Abstract: A grating has a high diffraction efficiency into the minus first diffracted order in transmission, for both TE and TM polarizations. The incident angle may optionally be chosen so that the minus first diffracted order in reflection would be retroreflected back to the incident beam. The grating may be formed from various materials and/or layers, where the thicknesses of the individual layers may be determined by an optimization or simulation process. In one aspect, the grating may have four or more layers, formed with three or more materials. In another aspect, the grating may have a longitudinal refractive index profile that contains at least two local extrema, such as a maximum and/or minimum. Such a grating may be formed from three or more materials, two materials, or a single material that has a continuously varying refractive index. Any or all of the materials may have a continuously varying refractive index profile, as well.

Abstract: A diffractive optical element includes at least a first diffractive element and a second diffractive element. The conditional expression 0.5?D/DS?0.9 is preferably satisfied where DS denotes the summation of the optimum designed groove height of the first diffractive element d1S and that of the second diffractive element d2S, and D denotes the summation of an actual groove height of the first diffractive element d1 and that of the second diffractive element d2. At least one of the first diffractive element and the second diffractive element is made of glass. At least one of the first diffractive element and the second diffractive element is made of resin. The optimum designed value of groove heights of the diffractive optical element are determined so as to satisfy a condition for correcting chromatic aberration at both d-line and g-line.

Abstract: A diffractive optical element includes a plurality of diffraction gratings. A diffraction grating within the plurality of diffraction gratings includes a plurality of grating parts having a curved grating surface and grating tips which connect to define a curved envelope face. The grating surface has a radius of curvature larger than a radius of curvature of the envelope face. In addition, two diffraction gratings within the plurality of diffraction gratings are composed of different materials having different dispersions. Therefore, even when the radius of curvature of the envelope face is small, the degradation of the diffraction efficiency is suppressed.