Abstract: An optical device includes a first birefringent crystal having a refractive index difference &Dgr;n1 and a length l1 and a second birefringent crystal having a refractive index difference &Dgr;n2 and a length l2. The first and second birefringent crystals are optically aligned and oriented so that a face of the first birefringent crystal and a face of the second birefringent crystal permit at least one optical beam to enter the face of the first birefringent crystal, pass through the first birefringent crystal, enter the face of the second birefringent crystal, and pass through the second birefringent crystal The face of the first birefringent crystal and the face of the second birefringent crystal are tilted relative to each other. The tilting adjusts at least the path length of optical beam through the first birefringent crystal, thereby permitting a precisely tuned frequency response without requiring corresponding precision in the length of the crystals.

Abstract: An external resonator type wavelength variable light source comprises a semiconductor laser 5 formed on one end face with a antireflection coating 5a, a lens 6 for converting emitted light from the end face of the semiconductor laser 5 formed with the antireflection coating 5a into collimated light, a diffraction grating 7 for selecting a wavelength of the collimated light provided through the lens 6 and diffracting the light, and a mirror for reflecting the light diffracted through the diffraction grating 7 and feeding back the light again diffracted through the diffraction grating 7 into the semiconductor laser 5 through the lens 6. A V-groove grating mirror 8 having reflecting faces with an arrangement like a grating, of a plurality of V grooves 2 each shaped like V at right angles in cross section in a base material 1 with a reflection coating 3 formed on the surface of each V groove is used as the mirror.

Abstract: An improved method is provided for reducing four-wave mixing induced degradation in an optical data signal traversing an optical transport network that uses Raman amplifiers. The method includes: introducing at least two Raman amplifiers into the optical transport network, each Raman amplifier having a laser source, and synchronously modulating the laser sources of the Raman amplifiers, thereby reducing four-wave mixing in the optical data signal. Modulation of the laser sources is performed at such a rate that crosstalk from the modulation to the optical data signals experiencing the Raman gain is minimized.

Abstract: An image recording apparatus and an image recording method can be suitably used for preparing a large number of edge-lit type holograms or holographic stereograms in a simple manner by copying. A hologram recording medium 11 is applied onto a principal surface 10a of a light-introducing block for copying 10 and held in contact with a master 15. Then, reference light L equivalent to reproducing light for reproducing the image of the master 15 is introduced into the light-introducing block for copying 10 through an end face thereof 10b.

Abstract: Apparatus for producing and guiding a light beam, in particular for a laser interferometer, includes a laser having a laser tube (100) and an external cavity (112). Two laser beams (110A′ and 110B′) of orthogonal polarization states are directed from the cavity into polarization maintaining fibers (12, 14). The two beams are generated from a single beam (110) by a birefringent prism (120) in the cavity. Additional beam steering prisms (130A and 130B) are included to direct the beams from the birefringent prism to the fibers. The additional steering prisms compensate for temperature induced beam deviations in the birefringent prisms. Interferometric sensing heads (20, 22) receive the beams from the fibers and include a rotatable wedge prism and mechanical adjustment means for guiding the beams onto reflecting surfaces on an object for positioning the object. The ends of the fibers attached to the sensing heads are kinematically located in the head.

Abstract: The invention describes an optical network architecture which uses a limited number of wavelength channels while providing flexible connections between the network nodes. Each node in the network deploys a fixed wavelength transmitter and a fixed wavelength receiver, whose wavelengths are misarranged so that a set of wavelengths of the transmitter differs from the set of wavelengths of the receiver, and wavelengths of transmitters and receivers at different nodes are arranged so that for any pair of nodes there is at least one common wavelength which is the same for one of the transmitter and receiver at one node and one of the respective receiver and transmitter at the other node, thus providing a direct connection between the nodes. The corresponding structure of the optical add/drop multiplexer/demultiplexer for use at the network node, and method of providing direct connections between the nodes, are also provided.

Abstract: An actuator mechanism for a tunable optical filter unit that filters a selected wavelength band of the input light from a DWDM input light. The input light comprises a plurality of wavelength bands or optical channels of light, each of which are centered at a respective channel wavelength. The actuator mechanism exerts a substantially linear force to strain or stress a tunable optical filter element to a desire reflection wavelength(s). A controller, in accordance with a control algorithm, provides a drive signal to the actuator mechanism in response to a command signal and a feedback signal indicative of the center wavelength of the desired optical channel(s) to be filtered. The actuator mechanism includes a drive mechanism that translates linearly a slide in response to the drive signal.

Abstract: A diffractive optical element acts as a lens. The optical element has a diffraction grating. The diffractive grating is provided with a plurality of ridges. Each of the ridges has a transmissive surface. A sectional profile of the transmissive surface is composed of a plurality of successively connected strait lines of an identical length. The length varies from one ridge to another.

Abstract: A holographic optical element comprising at least two sets of regions, the regions of each set being different from the regions of the other set(s) and being interleaved or overlapping with the regions of the other set(s) and being constructed such that light incident on each set of regions is directed to a respective one of a plurality of viewing zones. The holographic optical element is typically incorporated in a display device such as a stereoscopic display device.

Abstract: In a lens system having one or a plurality of diffracting surfaces and one or a plurality of refracting surfaces, a power of each surface and a distance between the surfaces are set such that an optical characteristic of the lens system, such as a focal length (focal point) and/or a spherical aberration, remains substantially unvarying relative to temperature variations within a predetermined range and that an achromatic effect is substantially attained for the focal length (focal point) and/or the spherical aberration within a predetermined region of wavelength.

Abstract: A diffractive optical element is composed of a plurality of diffraction gratings which differ in dispersion from each other and are laminated while being spaced to enhance diffraction efficiency for a particular order (design order) throughout an entire usable wavelength region, wherein edges of at least part of corresponding grating portions of the plurality of diffraction gratings are shifted from each other in a direction of arrangement of grating portions of each diffraction grating.

Abstract: An method, and method of production thereof, which provides excellent performance, reduced cost, and reduced breakage due to reduced manual handling. The present invention comprises a substrate, a bond layer coating the substrate, a reflective layer coating the bond layer, and a radiative layer coating the reflective layer. Preferably, the radiative layer comprises SiO2, Si3N4 or SiOxNy, low absorbency of electromagnetic radiation having wavelengths of approximately 200 nm to approximately 2500 nm and high absorbency and emissivity electromagnetic radiation having wavelengths of approximately 2.5 &mgr;m to approximately 25 &mgr;m. Preferably, the bond layer comprises chromium, titanium, or titanium-tungsten and the substrate comprises aluminum, aluminum alloys, polyimide, carbon-filled polyimide, or carbon composite.

Abstract: An optical element suitable for separating and converting directions of polarization, comprising polarization-separating members arranged in a row which extends transversely to an optical principal axis of the optical element for separating incident light from a light source into transmitted light having a first linear direction of polarization and reflected light having a second linear direction of polarization which, on a side facing the light source, is orthogonal to the first direction of polarization, which polarization-separating members have faces extending at an angle to the optical principal axis, while each polarization-separating member has a thickness in the direction of the optical principal axis and a width in a direction transverse to the optical principal axis.

Abstract: This invention provides a synthetic silica glass optical member used together with light having a specific wavelength of 250 nm or less, in which the difference between the maximum value and the minimum value of transmittance [%/cm] per cm in thickness for the light in a predetermined direction within a plane perpendicular to the optical axis is 2.0%/cm or less.

Abstract: A waveguide polarization recovery system both polarizes the input light energy for use with an LCD imager and converts the polarity of unusable light energy to add to the illumination of the LCD imager. The compact polarization recovery waveguide system generally includes: (1) an input waveguide that provides non-polarized light energy into the system; (2) an output waveguide that receives polarized light energy from the system; (3) a polarized beam splitter that received the light energy from the input waveguide and transmits lights energy of a first polarization type and reflects light energy of a second polarization type, and (4) a wave plate that modifies the polarization of either the transmitted or reflected light energy. The polarization recovery system also generally includes one or more mirrors that are positioned as need to direct the transmitted and the reflected light energy to the output waveguide. The input and output waveguides may be shaped as needed by the projection system.

Abstract: Bi-directional wavelength interleaving optical isolators provide the ability to pass a first set of optical signals (e.g., ITU even channels) from a first port to a second port, while preventing a second set of optical signals from passing thereto. The bi-directional wavelength interleaving optical isolators also pass the second set of optical signals (e.g., ITU odd channels) from the second port to the first port, while preventing the first set of optical signals from passing thereto. Thus, the bi-directional wavelength interleaving optical isolator can provide bi-directional communications by passing a first set of signals in a first direction and a second set of signals in a second direction.

Abstract: An attenuation filter contains absorbing thin film layers, which comprise gray metals or metal compounds. The attenuation filter offers significant advantages when used in optical communication systems subjected to a relatively high flux of incident light. It was surprisingly discovered that particular thin film materials provide significant protection to the attenuating thin film layer thereby improving the temporal stability and power handling capacity over prior art devices.

Abstract: A time compensation architecture for use with a plurality of optical signals is disclosed. It comprises means for receiving the plurality of optical signals, optical means for selectively delaying the propagation of each of the plurality of optical signals, and means for outputting the time delayed optical signals. The delay may be achieved by changing the indices of refraction or the material lengths of the elements and can either be an active or a passive compensation technique.

Abstract: A stereoscopic image pair may be viewed through a plate having an appropriately-sized aperture. When the viewer's left and right eyes view the image pair through the aperture, a stereoscopic effect may result. In one embodiment, a stereoscopic video conference system may include stereoscopic cameras positioned between the viewer and the apertured plate.

Abstract: A coloring structure includes a light-reflecting base, a brilliant layer placed on the base, and transparent brilliant units contained in the brilliant layer, each brilliant unit including an alternate lamination of at least two polymers having different refractive indexes, the lamination producing interfered light resulting from reflection and interference of light and transmitted light resulting from transmission of light, each brilliant unit controlling interfered and transmitted lights. The coloring structure is provided with a coloring mechanism for producing at least an interference color resulting from interfered light, a first object color resulting from reflection of transmitted light produced by the base, and a second object color resulting from reflection of incident light produced by the base without striking any brilliant units.