Abstract: A method for producing a library includes the steps of calculating a plurality of conditions for a reflection light from a periodic pattern by changing the sectional shape of the periodic pattern, a condition of an incident light which is emitted to the periodic pattern, an optical constant of a material which forms the periodic pattern, relating a plurality of the libraries to the plurality of the reflection light's conditions, and the optical constant corresponding to the plurality of the reflection light's conditions respectively.

Abstract: Novel methods are disclosed for designing and constructing miniature optical systems and devices employing light diffractive optical elements (DOEs) for modifying the size and shape of laser beams produced from a commercial-grade laser diodes, over an extended range hitherto unachievable using conventional techniques. The systems and devices of the present invention have uses in a wide range of applications, including laser scanning, optical-based information storage, medical and analytical instrumentation, and the like. In the illustrative embodiments, various techniques are disclosed for implementing the DOEs as holographic optical elements (HOEs), computer-generated holograms (CGHs), as well as other diffractive optical elements.

Abstract: A tunable optical resonator for use as a tunable laser or optical filter comprising a cavity in which the cavity is delimited by a reflection grating and a reflector in which the reflection grating is fixed to a flexible support, the resonator also comprising means for flexing the flexible support for causing the grating to mimic rotation about a selected point. A micro-mechanical tunable resonator as above providing mode-hop free tuning.

Abstract: Method and apparatus are disclosed for optical packet decoding, waveform generation, and wavelength multiplexing/demultiplexing using a programmed holographic structure. A configurable programmed holographic structure is disclosed. A configurable programmed holographic structure may be dynamically re-configured through the application of control mechanisms which alter operative holographic structures.

Abstract: In a holographic pattern provided in a holographic optical element, a pattern 1a twists a diffracted light beam in a clockwise direction, to form a semi-circular light spot Sa on photodetection parts A and B so as to extend over a dividing line LX in a four-segment photodetection part. A pattern 1b similarly twists the diffracted light beam in a clockwise direction, to form a semi-circular light spot Sb on photodetection parts C and D so as to extend over a dividing line LX in the four-segment photodetection part.

Abstract: This invention relates to a platform (11) and a method for generating electromagnetic field distributions. The invention relates in particular to optical sensors for measuring biological or chemical substances. The platform (11) according to the invention comprises a substrate (13), a structured layer (19) and, positioned between the substrate (13) and the structured layer (19), a multilayer assembly (17), said components being so matched relative to one another that upon appropriate impingement by electromagnetic radiation an electromagnetic field distribution is generated that is at a maximum within the structured layer (19).

Abstract: A diffraction grating with periodically arranged protrusions and grooves at a relatively narrow pitch and improved diffraction efficiency is disclosed. The protrusions of the grating are made of a material whose index of refraction is greater than that of the grooves, and the ratio of the width D of the protrusion to the pitch ? of the protrusion is set equal to or less than 0.4 (D/??0.4).

Abstract: A wavelength selective switching device and method for selectively transmitting optical signals based on wavelength utilizes diffraction to spatially separate the optical signals of different wavelengths such that the optical signal of a selected wavelength can be selectively transmitted. The wavelength selective switching device selectively rotates the polarization components of the optical signals such that the polarization states of the polarization components are the same in both incoming and outgoing directions at the diffraction grating. Thus, a diffraction grating with a high grating line frequency (e.g. greater than 900 grating lines per mm for signals in the 1550 nm wavelength range) can be used for diffracting the polarization components of the optical signals in both the incoming and outgoing directions.

Abstract: An optical imaging system and method for achieving a large depth of field without decreasing the relative aperture of an imaging lens. The imaging system has a light source for sequentially illuminating an object to be imaged with light of different ones of a plurality of wavelengths, and an imaging lens that has a focal length that varies with the wavelength of the light that illuminates the object. For each wavelength of light by which the object is illuminated, the imaging lens will image a different object plane onto an image receiving unit, and the image receiving unit will capture one well-focused, high resolution image of the object.

Abstract: A diffractive security element (2) is divided into surface portions, having an optically effective structure (9) at interfaces embedded between two layers of a layer composite (1) of plastic material. At least the base layer (4), which is to be illuminated, of the layer composite (1) is transparent. The optically effective structure (9) as a base structure has a zero order diffraction grating with a period length of at most 500 nm. In at least one of the surface portions an integrated optical waveguide (5) with a layer thickness (s) of a transparent dielectric is embedded between the base layer (4) and an adhesive layer (7) of the layer composite (1) and/or a protective layer (6) of the layer composite (1), wherein the profile depth of the optically effective structure (9) is in a predetermined relationship with the layer thickness (s).

Abstract: An optical element is provided that may be used for collecting optical radiation incident at large angles of incidence. The element may include a grating window formed of grating elements that may collect large incident angle radiation and reflect that radiation, e.g., under total internal reflection in a substantially normal direction. A lens or lens array may be used to collect the internally reflected radiation and focus that radiation to a detector. Example detectors include infrared detectors. The element may be formed to collect, reflect, and redirect optical radiation incident at angles above 45° as measured from a surface normal to a detector oriented substantially at normal incidence. The detected signal from the optical element may be used to control systems within an aircraft or other vehicle capable of flight.

Abstract: The present invention provides a MEMS device and methods for manufacturing thereof, in which planarizing the surface of a beam and improving performance of the MEMS device are aimed. In addition, the present invention provides a light modulation device and a GLV device in which this MEMS device is used, and methods for manufacturing thereof; and further, a laser display using this GLV device. According to the present invention, a MEMS device includes a substrate side electrode and a beam that is disposed so as to oppose the substrate side electrode and is driven by electrostatic attraction force or electrostatic repulsion force that acts between the substrate side electrode and the driving side electrode, with the substrate side electrode being formed of a single-crystalline semiconductor layer.

Abstract: A method for manufacturing a diffusion grating-based optical identification element is provided. The optical identification element includes a known fiber substrate, having a diffraction grating disposed therein the grating being indicative of a code when exposed to incident light. A large number of elements or microbeads all having the same identification codes can be manufactured by cutting the substrate transversely where the grating is located, thereby creating a plurality of elements, at least two of the elements having the grating therein along substantially the entire length of the elements. The elements may be manufactured in many different ways, including winding the fiber onto a basket, forming the gratings in the basket openings or bays, removing the fiber and cutting the fiber to form the elements 8. Each bay may have a set of elements with a unique set of codes therein.

Abstract: A diffraction element includes a light-transmittable member and a diffraction grating formed on at least one face of the light-transmittable member. When a first laser beam having a first wavelength ?1 and a second laser beam having a second wavelength ?2 are transmitted through the diffraction element at first and second diffraction efficiencies, respectively, the diffraction element functions to equalize the first and second diffraction efficiencies to each other by only the one face of the diffraction element. The diffraction grating has a first phase modulation amount ø1 for the first laser beam and a second phase modulation amount ø2 for the second laser beam and the first and second phase modulation amounts ø1 and ø2 are, respectively, approximate to (2?N1±?ø) and (2?N2±?ø) in which “N1” and “N2” are natural numbers and “?ø” is a phase variation amount.

Abstract: A light guide plate (20) has a light incidence surface (221) for receiving light, a light emitting surface (223) for emitting light, and a bottom surface (222). The light emitting surface has a plurality of diffraction grating units. Each diffraction grating unit has a strong diffractive portion and a weak diffractive portion. In each diffraction grating unit, grating directions of the strong and weak diffractive portions are orthogonal to each other. Area ratios of the strong diffractive portions in the diffraction grating units progressively increase with increasing distance away from the light incidence surface. The grating directions of the strong diffractive portions may vary according to the locations of the diffraction grating units relative to a light source. These features improve the overall efficiency of utilization of light, and enable the light emitting surface to output highly uniform light.

Abstract: The invention relates to a diffractive optical system having a two-dimensional structure, which can be used as a phase shift mask for the fabrication of an optical element having a two-dimensional fine periodic structure, and a two-dimensional light beam splitter. The diffractive optical system 10 comprises a transparent substrate surface 1 that is divided in alignment with orthogonal two directions into minuscule square cell groups 2, 3 of the same shape in a checked pattern. The square cells that give a phase 2p? and a phase {(2q+1)?±??} where 0???0.25 and p and q are each an integer with respect to reference-wavelength light striking vertically on the transparent substrate surface 1 are alternately arranged in each direction, and the phase 2p?-giving square cells and the phase {(2q+1)?±??}-giving square cells are located in such a way as to be in alignment with 45° diagonal directions of said two directions.

Abstract: A reflective grating for precision location measurement. In one embodiment, the reflective grating has a non-reflective substrate and a non-reflective adhesion layer disposed on the substrate layer. A reflective surface layer is disposed on the adhesion layer. In another embodiment, the reflective grating is manufactured on the reflective (polished) surface of a monolithic substrate. A series of grating lines are formed in the reflective surface layer by vaporizing portions of the reflective surface layer with a laser in order to expose the non-reflective adhesion layer. Accordingly, alternating reflective and non-reflective grating lines are formed that are used for making precision measurements.

Abstract: A wavelength selective switching device and method for selectively transmitting optical signals based on wavelength utilizes diffraction to spatially separate the optical signals of different wavelengths such that the optical signal of a selected wavelength can be selectively transmitted. The wavelength selective switching device selectively rotates the polarization components of the optical signals such that the polarization states of the polarization components are the same in both incoming and outgoing directions at the diffraction grating. Thus, a diffraction grating with a high grating line frequency (e.g. greater than 900 grating lines per mm for signals in the 1550 nm wavelength range) can be used for diffracting the polarization components of the optical signals in both the incoming and outgoing directions.

Abstract: An optical pickup apparatus having laser light sources emit a first light beam having a relatively shorter wavelength for a DVD and a second light beam having a longer wavelength for a CD-R, an objective lens having a focal length of an information recording surface in the DVD, an optical path control unit controls the light beams so that the light beam emitted from one of the laser light sources is directed to the objective lens and the light output from the objective lens is directed to the optical detection unit, and a phase shift unit between the optical path control unit and the objective lens and which shifts a phase of the second light to reduce the size of a beam spot which is formed the information recording surface in the CD-R.

Abstract: An optoelectronic device that provides an excellent reproduction signal and a stable servo control while preventing deterioration of S/N ratio caused by stray light. The optoelectronic device has a semiconductor laser (101) that emits light beams on an information-recording medium (105), a hologram optical element (102) having a diffraction grating region (108) and located between the semiconductor laser (101) and the information-recording medium (105), and a photodetector (106) for receiving light that is diffracted at the diffraction grating region (108) of the hologram optical element (102), among returning light beams from the information-recording medium (105), and the optoelectronic device has also a diffraction grating region (107) in the vicinity of the diffraction grating region (108) of the hologram optical element (102) so as to prevent stray light other than diffracted light from the diffraction grating region (108) from entering the photodetector (106).

Abstract: A wavelength selective optical switch particularly usable as a programmable N×M optical switch in a multi-wavelength communication system. The switch uses a grating that separates multi-channel optical signals into a plurality of optical channels, and combines a plurality of optical channels into multi-channel optical signals. Programmable mirrors switch each optical channel to any of a plurality of fibers coupled to the switch.

Abstract: A diffractive optical element includes a first diffractive element and a second diffractive element that is made of a material different from that of the first diffractive element and is cemented with the first diffractive element, forming a diffraction grating at the cemented surface. A shade film is formed on a wall surface of each groove of the diffraction grating to enhance the angular characteristic of the grating.

Abstract: Disclosed is a light modulator having a digital micro blaze diffraction grating. In the light modulator, a fine protrusion is formed on an edge of a lower surface of a diffraction member so that a reflective surface inclines due to the fine protrusion when the diffraction member is drawn downward.

Abstract: A plastic lens includes refractive and diffractive optical apparatus configured to produce optothermal changes substantially canceling each other over a predetermined working temperature range to render the plastic lens substantially athermalized over the range.

Abstract: An apparatus for forming a nano grating device to film nano-scale interference fringes by holography in order to makes a nano-scale meshed structure is disclosed. A beam emitted form a light source passes subsequently through a beam splitter and two reflectors to reach at symmetrically mounted light emitting modules. The light emitting modules generate two beams passing along the same optical paths and then projecting on a photosensitive substrate that is attached on a hemi-sphere lens. Thus, a first set of interference fringes are formed. Then, the substrate rotates with an angle and then is subjected to exposure to form a second set of interference fringes crossing the first set of interference fringes. Thereby, a nano-scale meshed structure is obtained.

Abstract: An optical packet header identifier having a simplified configuration and being superior in reliability, stability, and economical efficiency, an optical router incorporating the identifier therein, and a routing method using the optical router are provided. The optical packet header identifier includes an optical waveguide, optical focusing elements, and a photo receiver. Tilted gratings for diffracting an incident optical beam and emitting the beams as diffracted optical beams to the outside of the waveguide are formed within the optical waveguide. The tilted gratings are not formed uniformly in a longitudinal direction of a core of the optical waveguide, but are arranged at intervals. The length of a portion containing a set of gratings and the length of a portion containing no gratings can be defined in increments of length “L”. “L” equals to the spatial length which 1 bit in an optical signal occupies.

Abstract: A diffraction optical device includes a first diffraction element and a second diffraction element arranged adjacent to each other. One of the first diffraction element and the second diffraction element has a positive power, and the other has a negative power. The first diffraction element reduces the incident angle of light upon the second diffraction element. As a result, a lowering of diffraction efficiency due to the dependency thereof upon the incident angle of light is suppressed, and flare light is prevented from occurring due to diffracted light of unnecessary orders.

Abstract: Method and apparatus are disclosed for optical packet decoding, waveform generation and wavelength multiplexing/demultiplexing using a programmed holographic structure. A configurable programmed holographic structure is disclosed. A configurable programmed holographic structure may be dynamically re-configured through the application of control mechanisms which alter operative holographic structures.

Abstract: A security element for sticking onto a document comprises a layer composite of plastic material and has embedded, optically effective structures of a pattern . The optically effective structures in surface portions of the pattern are in a reference plane, defined by co-ordinate axis (x; y), of the layer composite and are shaped into a reflecting interface. The interface is embedded between a transparent shaping layer and a protective layer of the layer composite. At least one surface portion is of a dimension of greater than 0.4 mm and in the interface has at least one shaped macrostructure which is an at least portion-wise steady and differentiatable function of the co-ordinates (x; y). The macrostructure is curved at least in partial regions and is not a periodic triangular or rectangular function. In the surface portion adjacent extreme values of the macrostructure are at least 0.1 mm away from each other.

Abstract: In a holographic digital data storage system, a light source generates a reference beam, a holographic optical element saves a plurality of interference patterns between the reference beam and a plurality of beams of specific sizes and a beam splitter splits each reproduced beam into a holographic signal beam and a holographic reference beam. A medium records an interference pattern between the holographic reference beam and the holographic signal beam and reflecting the holographic reference beam to generate a reflective information beam and, if only the holographic reference beam is illuminated, a displaying means displays a holographic reproduced beam for the holographic signal beam and detecting the reflective information beam.

Abstract: A dispersion compensator having relatively uniform transmission characteristics over the bandwidth of a communication channel. The compensator is designed to process an optical signal corresponding to the communication channel by decomposing that signal into spectral components, routing different components along different optical paths that impart relative delays between the components, and recombining the delayed components spatially and directionally to generate a processed optical signal with reduced chromatic dispersion. In one embodiment, the compensator includes a diffraction grating optically coupled to a mirror array, in which different mirrors receive light corresponding to different communication channels. For each channel, a desired group delay value is produced by selecting the curvature of the corresponding mirror. A compensator employing independently addressable, variable-curvature mirrors enables generation of variable, channel-specific group delays.

Abstract: In a volume phase grating, a plurality of phase gratings for causing a refractive index of a substrate having an incident surface and a launched surface facing each other to be cyclically changed between the incident surface and the launched surface are so formed as to be inclined at a specified angle to the incident surface. The volume phase grating is constructed such that an incident light is caused to be obliquely incident on the incident surface, and an angle of inclination of the phase gratings to the incident surface is set such that the incident light obliquely incident on the incident surface is refracted at the incident surface and perpendicularly incident on the phase gratings.

Abstract: A method of wave propagation from 100–10000 GHz. The currently disclosed method and apparatus adapts micro-opto-electro-mechanical systems (MOEMS) technologies and processes to construct Kinoform optical components from microwave to terahertz range. The method uses induced coupled plasma (ICP) and gray scale processes for upper terahertz band; LIGA-based high aspect ratio (HAR) and gray scale processes are for the mid band; and computer numerical control (CNC) for lower band. In all cases, the thickness of any processed components is about the respective wavelength and system efficiency is about 95%. A Kinoform lens element is designed at 5000 GHz. However, the method is applicable for the entire terahertz band.

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

Abstract: A diffracting optical element has a structure that a plurality of layers having a periodic relief pattern varying in height in a period are laminated in proximity to or close contact with each other. The diffracting optical element includes two layers equal in the height of the relief pattern and opposite to each other in the direction in which the height of the relief pattern varies in a period, and another layer differing in the height of the relief pattern from the two layers. Materials forming the three layers differ in dispersion from one another.

Abstract: A diffractive optical element emits substantially zero order diffracted light when light with a wavelength of 0.35 ?m to 0.45 ?m is incident and emits substantially first-order diffracted light when light with a wavelength of 0.6 ?m to 0.7 ?m is incident. The diffractive optical element includes a substrate and a grating portion formed on the substrate. The grating portion has a step-wise cross section with any one of levels selected from four levels, five levels and six levels. The diffractive optical element emits substantially zero-order diffracted light when light with a first wavelength ?1 satisfying the relationship: 0.35 ?m??1?0.45 ?m is incident and emits substantially first-order diffracted light when light with a second wavelength ?2 satisfying the relationship: 0.6 ?m??2?0.7 ?m is incident.

Abstract: An optical pickup apparatus having laser light sources emit a first light beam having a relatively shorter wavelength for a DVD and a second light beam having a longer wavelength for a CD-R, an objective lens having a focal length of an information recording surface in the DVD, an optical path control unit controls the light beams so that the light beam emitted from one of the laser light sources is directed to the objective lens and the light output from the objective lens is directed to the optical detection unit, and a phase shift unit between the optical path control unit and the objective lens and which shifts a phase of the second light to reduce the size of a beam spot which is formed the information recording surface in the CD-R.

Abstract: An apparatus providing full spectrum electronic images includes a full-spectrum light source, a programmable diffraction grating to separate light from the source into its spectral components, a reflection system controllable on a pixel by pixel basis to modulate light output from the diffraction grating, and a scanning mirror to form an image from light modulated by the reflection system. A related method for displaying a full spectrum image includes providing full spectrum light, using a diffraction grating to separate the light into its spectral components, and for each pixel of the image, modulating the intensity of the spectral components to produce a light output characteristic of such pixel, and additionally using a scanning mirror arrangement to form the image.

Abstract: The invention concerns an optically variable element, in particular an optically variable safeguard element for safeguarding banknotes, credit cards and the like, and a security product and a foil, in particular an embossing foil or a laminating foil, with such an optically variable element. The optically variable element has a thin film layer (54, 55, 58) for producing color change by means of interference and a further layer (51, 52, 53, 59). The thin film is in the form of a partial thin film element which covers the surface region of the further layer only in region-wise and pattern-shaped manner.

Abstract: A liquid crystalline transfer sheet 10 includes a liquid crystal layer 12 formed on the surface of a substrate 14, where the surface hardness of the liquid crystal layer 12 is higher on the releasing surface 12A side, which is on the substrate 14 side, than on the adhering surface 12B side, which is on the receiving object 16 side. Therefore, the adhesion between the adhering surface 12B of the liquid crystal layer 12 and the receiving object 16 becomes stronger than that between the releasing surface 12A of the liquid crystal layer 12 and the substrate 14. It is thus possible to securely transfer the liquid crystal layer 12 to the receiving object 16 without leaving a part of the liquid crystal layer 12 on the substrate 14.

Abstract: A method and apparatus for converting a Gaussian laser beam into a propagating far field diffraction pattern using an off-axis diffractive optic. This propagating far field pattern is focused by a lens to obtain a flattop intensity at the focal plane. The technique is based on the idea of Fourier transform pairs and produces a small spot diameter with a useable depth of field. A focused uniform intensity profile can be useful for many laser applications.

Abstract: A volume diffractive composite is disclosed for providing illumination at a first output angle. The volume diffractive composite comprises a first plurality of grating elements that are mutually spaced from another in a first position with a first spacing period along a first plane, and an actuation unit for changing at least one of the position or the spacing period of the first plurality of grating elements to a second position or spacing period to provide illumination at a second output angle.

Abstract: Optical transceivers include a diffractive optical element (DOE) attached to a surface of a prism or other optical support. The DOE is configured to direct an input optical signal to a planar or curved reflective surface, or receive an output optical signal from the planar or curved reflective surface at angles greater than a critical angle in the prism. In some examples, the optical support includes one or more curved reflective surfaces and the DOE is a hologram. Such optical transceivers include a reflective surface that is rotatable with respect to the DOE, or with respect to a selected communication direction and the DOE for selection of a transmission or reception direction. The optical supports of such optical transceivers can be mounted to a window, and include a reflective region configured to total internally reflect optical signals. Selection of a communication direction is based on a rotation of the rotatable reflective surface.

Abstract: An optical device includes a plurality of metallic stripes, arranged in a substantially planar, subwavelength grating having a laterally varying, continuous grating vector, deposited on a substrate such as GaAs or ZnSe. When used as a polarizer, the device passes a laterally uniform polarized beam of electromagnetic radiation incident thereon with a predetermined, laterally varying transmissivity. When used to effect polarization state transformation, the device transforms a beam of electromagnetic radiation incident thereon into a transmitted beam having a predetermined, laterally varying polarization state. The device can be used to provide radially polarized electromagnetic radiation for accelerating subatomic particles or for cutting a workpiece. The device also can be used, in conjunction with a mechanism for measuring the lateral variation of the intensity of the transmitted beam, for measuring the polarization state of the incident beam.

Abstract: A DOE homogenizer including a plurality of parallel lasers emitting Gaussian beams of a diameter d along beam lines extending in a z-direction and aligning at a pitch p in an x-direction, and off-axis DOEs diffracting the Gaussian laser beams at inclining diffraction angles, making quasi-uniform density q×w (q>w) stripe-sectioned beams on an image plane I (xy-plane) which is distanced by a focal length f from the DOEs and aligning at the pitch p on an x-direction extending base line K vertical to the beam lines in an order of larger inclining diffraction angles outward and smaller inclining diffraction angles inward on extensions of the beam lines of the lasers, the DOEs diffracting the laser Gaussian beams into the quasi-uniform density stripe-sectioned beams, superposing the diffracted beams partially at edges and making a unified x-direction extending quasi-uniform beam on the image plane I.

Abstract: A uniform coating is provided using surface features. Multiple ridges or other shapes are fabricated near an area of interest to allow for uniform coating in between the ridges. Areas at either ends of the ridges are left open to allow for excess pooling of photoresist liquid and to aid in obtaining uniform coating. The photoresist liquid or other coating fluid is applied to the sample and spun dry. A soft-bake process is performed to evaporate remaining solvents. An element, such as a diffractive, refractive, or reflective grating structure, is then formed in the area of interest using the uniform photoresist coating.

Abstract: Method and apparatus are disclosed for optical packet decoding, waveform generation and wavelength multiplexing/demultiplexing using a programmed holographic structure. A configurable programmed holographic structure is disclosed. A configurable programmed holographic structure may be dynamically re-configured through the application of control mechanisms which alter operative holographic structures.

Abstract: A diffractive optical element includes a first diffractive optical part having a phase type diffractive grating, and a second diffractive optical part having a phase type diffractive grating formed of a material differing from that of the first diffractive optical part. The first diffractive optical part and the second diffractive optical part are disposed in proximity to each other with an air layer. Each of the first diffractive optical part and the second diffractive optical part has a mark for aligning them with the optical effective areas thereof.

Abstract: The present invention relates to an optical component and the like having a structure that can increase the absolute value of the angular dispersion, and also can reduce the temperature dependence of the diffraction angle. The optical component comprises a diffraction grating element of a transmissive type and a prism. The prism is composed of a material with a refractive index of n1, and the diffraction grating element and the prism are surrounded a material with a refractive index of n0.

Abstract: Provided is a Fresnel lens the manufacture of that is unlikely to be affected by the working errors of the die in the optical axis and its neighborhood. Two lens surfaces 11, 11 that are disposed in the vicinity of the optical axis are disposed in the way they are shifted from each other in a direction along the optical axis, whereby the height Ha in this direction of the optical axis of a non-lens surface 12 located at the boundary between the two lens surfaces 11, 11 is made greater than an original height Ha of the non-lens surface 12 in a case where it is assumed that the lower ends 11a, 11a of each of these lens surfaces 11, 11 has been placed on the same flat plane intersecting the optical axis OA at a right angle with respect thereto. Also, the lens angle ?a of at least one piece of lens surface 21 that is disposed in the vicinity of the optical axis is set to be greater than the original lens angle that should be given according to the focus calculation with respect to the lens angle 21.