Abstract: A space variant polarization optical element for spatially manipulating polarization-dependent geometrical phases of an incident light beam. The element comprises a substrate with a plurality of zones of gratings with a continuously varying orientation. The orientation denoted by ?(x-y) is equal to half of a desired geometrical phase (DGP) modulus 2?. Each grating has a local period that is smaller than the wavelength of the incident light beam. In other embodiments of the present invention the substrate comprises a plurality of zones of gratings with a continuously varying orientation.

Abstract: A method for fabricating an optical identification element is provided, wherein a removable plate or substrate having photosensitive material fabricated thereon, one or more gratings are written on the photosensitive material, then lines are etched to create one or more separate optical identification elements. The one or more gratings may be written by exposing the photosensitive material to ultraviolet (UV) light. The lines may be etched to create the one or more separate optical identification elements by photolithography to define/create the same.

Abstract: An optical device includes a light guide plate, and first and second reflective volume hologram diffraction grating members. The first member has interference fringes extending from therewithin towards surfaces thereof and arranged at an equal pitch. Each interference fringe and each surface of the first member form an inclination angle therebetween. The first member has the following conditions. (a) In an outer region positioned farther away from the second member than a minimum inclination angle region having a minimum inclination angle, the inclination angles of the interference fringes increase with increasing distance from the minimum inclination angle region. (b) In an inner region positioned closer to the second member than the minimum inclination angle region, the inclination angles of the interference fringes include a maximum inclination angle in an inner area disposed adjacent to the minimum inclination angle region and decrease with increasing distance from the minimum inclination angle region.

Abstract: A device for projecting an object in a space of a vehicle is described. This object is preferably projected holographically, and a voice input and output system is assigned to this object. An artificial passenger is thus created for a driver.

Abstract: In a diffraction grating element 10, between a first medium 11 and a fourth medium 14, a second medium 12 and a third medium 13 are disposed alternately to form a diffraction grating. The light, which enters the diffraction grating from the first medium 11, is diffracted at the diffraction grating portion and output to a fourth medium 14. Or, the light, which enters the diffraction grating from the fourth medium 14, is diffracted at the diffraction grating portion and output to the first medium 11. The index of refraction n1-n4 of each medium satisfies a relational expression of “n3<n1<n2, n3?n4?n2” or “n3?n1?n2, n3<n4<n2”.

Abstract: The present invention provides a multi-channel tunable filter and methods for making such a filter. In one embodiment, the filter comprises a bank of gratings or a continuously varying filter frequency imprinted into a filter material, such as Lithium Niobate or glass or polymer. An optical read-head comprising a pair of lenses is configured to pass light from within an optical fiber carrying multiple wavelengths through an appropriate grating to extract or drop a specific wavelength. To ensure continuous data transmission, the filter is tuned to a wavelength by configuring the read-head to move in a hitless manner. In one embodiment, the gratings are recorded by the interference of two beams. A first plane wave reflects off a first mirror stack and a second plane wave reflects off a second mirror stack. In another embodiment, the gratings are recorded by a phase masking method.

Abstract: An optical tunable filter has a fixed substrate having a first recess formed therein and a movable substrate bonded to the fixed substrate. The movable substrate includes a movable portion having an opening formed at a location facing the first recess and a support portion for supporting the movable portion so that the movable portion can be displaced. The optical tunable filter also has a light-transmittable substrate bonded to the movable portion, a fixed reflection film formed on a bottom of the first recess, and a movable reflection film formed on a surface of the light-transmittable substrate. The optical tunable filter includes an interference gap formed between the fixed reflection film and the movable reflection film. The optical tunable filter also includes an actuator operable to displace the movable portion relative to the fixed substrate.

Abstract: A security device comprises a holographic or diffractive optically variable effect generating structure which, when viewed normally i.e. perpendicularly to the plane of the device, replays at least one composite image, the composite image being defined by at least a pair of discrete image elements, the structure being such that at least two of the discrete image elements of the composite image have different optimal replay angles.

Abstract: Aspects of the present invention are generally directed to a holographic system. Generally, aspects of the present invention are directed to allocating power of a light beam generated by a coherent light source among the various discrete light beams used in a holographic system. Specifically, a variable optical divider is incorporated into an optical steering subsystem of the holographic memory system to redirect the coherent light beam into one or more discrete light beams, and to dynamically allocate power of the coherent light beam among the discrete light beams.

Abstract: A hologram device records information of an interference fringe of signal light and reference light onto a hologram recording medium and reproduces the recorded information by emitting the reference light onto a recording area of the hologram recording medium. The hologram device includes a recording/reproducing controller performing a recording operation of the information concurrently with a reproducing operation of previously-recorded information, and an error detector detecting an error in the previously-recorded information reproduced concurrently with the recording operation.

Abstract: This invention is a holographic recording medium including a track in which position information to specify a recording position and a reproducing position of page data is formed. The position information of the track is formed of position detection patterns. The position detection patterns each including a first detection mark row including center pits arranged at predetermined intervals; and a second detection mark row including side marks arranged at the same intervals as the intervals of the center pits, the side marks having lengths substantially corresponding to integral multiples of the intervals of the center pits. The second detection mark row is arranged adjacent to the first detection mark row such that both ends of the side marks are arranged so as to correspond to the center pits in a track width direction, and page data is recorded and reproduced on the basis of positions of the center pits or positions of the ends of the side marks.

Abstract: This invention relates to a configurable diffractive optical element comprising an array of diffractive sub-elements having a reflective surface, wherein each sub-element has a controllable position with a chosen range, and in which a number of sub-elements are provided with a reflective grating with a number of chosen spectral characteristics.

Abstract: In an optical communication method, an accurate common clock signal (GPS) is provided to a sender (10) and a receiver (20). In the sender, the common clock signal is received, a first clock signal (CLK1) is generated on the basis of said common clock signal, a carrier wave with a predetermined carrier frequency (f) is generated using said clock signal as timing reference, the carrier wave is modulated with a data signal, and the modulated carrier wave is transmitted using a light beam (13). In the receiver, the common clock signal is received, a reference signal having the same frequency (f) as the carrier frequency is generated on the basis of said common clock signal, said optical beam (13) is received, a detection signal is derived from the optical beam, the receiver is tuned to the predetermined carrier frequency (f), and the data signal is derived from the detection signal.

Abstract: The exposure amounts of R, G, and B laser light emitted from a fabrication light source are so adjusted that the diffraction efficiency at R, G, and B wavelengths in an optical element is commensurate with the light intensity at the R, G, and B wavelengths in the light emitted from a reproduction light source. For example, when the light intensity of the light emitted from the reproduction light source is increasingly low at the B, G, and R wavelengths in this order, the exposure amounts of the R, G, B, laser light emitted from the fabrication light source are so adjusted that the diffraction efficiency in the optical element is increasingly high at the B, G, and R wavelengths in this order. In this way, the hue of the light (reproduction light) obtained from the reproduction light source via the optical element can be adjusted to the hue desired with every reproduction light source used, while the most use is made of the light emitted from the reproduction light source actually used.

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 laser light beam of a first wavelength which is polarized in a first polarizing direction, emitted from first and second semiconductor laser elements and reflected by an information recording surface of an optical recording medium, is made to be transmitted by a second polarizing hologram diffraction grating and diffracted in a direction toward a light receiving element by a first polarizing hologram diffraction grating. A laser light beam of a second wavelength which is polarized in the first polarizing direction, reflected by the information recording surface of the optical recording medium, is made to be converted so to be in a second polarizing direction by the 5?/4 plate. A laser light beam of the second wavelength which is polarized in the second polarizing direction is made to be diffracted in the direction toward the light emitting element by the second polarizing hologram diffraction grating.

Abstract: A display device for a vehicle includes a transparent window with a light emission layer intended to separate the interior of the vehicle for emitting visible light when light is beamed onto the light emission layer, a light source for beaming light onto the window, a reflector mounted in a light path between the light source and the window to reflect the light generated by the light source and an adjustable image generator located between the light source and the reflector.

Abstract: A light quantity distribution control element includes a substrate of 20 mm×20 mm×3 mm made of a material that transmits light, such as optical glass or acryl, and a antireflective structure provided on a surface of the substrate. As the antireflective structure, a conical antireflective structure of a pitch of 0.15 ?m (periodic structure having conical convexities) is formed. This corresponds to a antireflective structure having a pitch of a wavelength or less in the ultraviolet band (150 nm to 400 nm) at the time when ultraviolet light is used as incident light.

Abstract: A beam steering system having first diffraction gratings, each one being associated with a corresponding one of a first plurality of grating vectors disposed substantially in a first plane. The gratings diffract optical energy from any one of a plurality of input directions of resonance to a corresponding one of a plurality of output directions. Second diffraction gratings are associated with a second plurality of grating vectors disposed substantially in a second plane. Each one of the second gratings diffracts optical energy from any one of a plurality of input directions of resonance to a corresponding one of a plurality of output directions.

Abstract: Disclosed is a method of producing a hologram through a two-beam laser interfering exposure process, which comprises emitting a coherent laser light with a pulse width (?) ranging from greater than 900 femtoseconds to 100 picoseconds and a laser power of 10 ?J/pulse or more using a solid-state laser as a light source, dividing the pulses light from the laser into two beams, controlling the two beams temporally and spatially in such a manner that the two beam are converged on a surface of or inside a workpiece for recording a hologram while matching the respective converged spots of the two beams with one another temporally and spatially to create the interference therebetween so as to record a surface-relief hologram on the surface of the workpiece or an embedded hologram inside the workpiece in an irreversible manner.