557 results about "Spectral filtering" patented technology

An optical fiber for transmitting radiation comprising two or more core regions, two or more core regions, each core region comprising a substantially transparent core material and having a core refractive index, a core length, and a core diameter, wherein said core regions are arranged within a cladding region, said cladding region comprising a length of first substantially transparent cladding material, having a first refractive index, wherein said first substantially transparent cladding material has an array of lengths of a second cladding material embedded along its length, wherein the second cladding material has a second refractive index which is less than said first refractive index, such that radiation input to said fiber propagates along at least one of said core regions. The cladding region and the core regions may be arranged such that radiation input to said optical fiber propagates along one or more said lengths of said core regions in a single mode of propagation. The optical fiber may be used as a bend sensor, a spectral filter or a directional coupler. The invention also relates to a method of manufacturing a multicore optical fiber.

A hyperspectral imager that achieves accurate spectral and spatial resolution by using a micro-lens array as a series of field lenses, with each lens distributing a point in the image scene received through an objective lens across an area of a detector array forming a hyperspectral detector super-pixel. Spectral filtering is performed by a spectral filter array positioned at the objective lens so that each sub-pixel within a super-pixel receives light that has been filtered by a bandpass or other type filter and is responsive to a different band of the image spectrum. The micro-lens spatially corrects the focused image point to project the same image scene point onto all sub-pixels within a super-pixel.

A pulsed laser comprises an oscillator and amplifier. An attenuator and / or pre-compressor may be disposed between the oscillator and amplifier to improve performance and possibly the quality of pulses output from the laser. Such pre-compression may be implemented with spectral filters and / or dispersive elements between the oscillator and amplifier. The pulsed laser may have a modular design comprising modular devices that may have Telcordia-graded quality and reliability. Fiber pigtails extending from the device modules can be spliced together to form laser system. In one embodiment, a laser system operating at approximately 1050 nm comprises an oscillator having a spectral bandwidth of approximately 19 nm. This oscillator signal can be manipulated to generate a pulse having a width below approximately 90 fs.

Waveguide grating devices. One includes at least one waveguide having an end, the end having an endface; and a waveguide grating fabricated on the endface, the waveguide grating having at least one waveguide layer and at least one grating layer. The waveguide layer is a separate waveguide from the waveguide on which the waveguide grating is fabricated. Systems for spectral filtering. One, which utilizes a guided-mode resonance effect in a waveguide, includes at least one waveguide having a proximal end and a distal end having an endface; and a waveguide grating fabricated on the end of the waveguide and having a plurality of variable parameters such as permittivity of the grating layer(s) and permittivity of the waveguide layer(s). Methods of forming waveguide grating devices, and methods of detecting one or more parameters of a medium using a waveguide grating device are also disclosed.

An illumination panel for illuminating an object, comprising a substrate, a light diffractive grating and a light source. The substrate is made from an optically transparent material having first and second area surfaces disposed substantially parallel to each other and a light input surface for conducting a light beam into the substrate. The light diffractive grating is mounted to the first areal surface and has a slanted fringe structure embodied therein for diffracting the light beam falling incident thereto, along a first diffractive order of the slanted fringe structure. The light source produces a light beam for transmission through the input surface and direct passage through the substrate to the slanted fringe structure so as to produce an output light beam of areal extent that emerges from either the first or second areal surface along the first diffractive order, for use in illuminating an object. A spatial-intensity modulation panel can be mounted to the illumination panel to form a color image display device. In the illustrative embodiments, the light diffractive grating is a volume hologram that is pixelated and spectrally-tuned in order to carry out spectral filtering functions within the color image display device.

A two-dimensional focal plane array (FPA) is divided into sub-arrays of rows and columns of pixels, each sub-array being responsive to light energy from a target object which has been separated by a spectral filter or other spectrum dividing element into a predetermined number of spectral bands. There is preferably one sub-array on the FPA for each predetermined spectral band. Each sub-array has its own read out channel to allow parallel and simultaneous readout of all sub-arrays of the array. The scene is scanned onto the array for simultaneous imaging of the terrain in many spectral bands. Time Delay and Integrate (TDI) techniques are used as a clocking mechanism within the sub-arrays to increase the signal to noise ratio (SNR) of the detected image. Additionally, the TDI length (i.e., number of rows of integration during the exposure) within each sub-array is adjustable to optimize and normalize the response of the photosensitive substrate to each spectral band. The array provides for parallel and simultaneous readout of each sub-array to increase the collection rate of the spectral imagery. All of these features serve to provide a substantial improvement in the area coverage of a hyperspectral imaging system while at the same time increasing the SNR of the detected spectral image.

The present invention relates to the production of instantaneous or non-instantaneous multi-band images, to be transformed into multi- or hyperspectral images, comprising light collecting means (11), an image sensor (12) with at least one two dimensional sensor array (121), and an instantaneous colour separating means (123), positioned before the image sensor array (121) in the optical path (OP) of the arrangement (1), and first uniform spectral filters (13) in the optical path (OP), with the purpose of restricting imaging to certain parts of the electromagnetic spectrum. The present invention specifically teaches that a filter unit (FU) comprising colour or spectral filter mosaics and / or uniform colour or spectral filters mounted on filter wheels (114) or displayed by transmissive displays (115), is either permanently or interchangeably positioned before the colour separating means (123) in the optical path (OP) in, or close to, converged light (B). Each colour or spectral filter mosaic consists of a multitude of homogeneous filtering regions. The transmission curves (TC) of the filtering regions of a colour or spectral filter mosaic can be partly overlapping, in addition to overlap between these transmission curves and those belonging to the filtering regions of the colour separating means (123). The transmission curves (TC) of the colour or spectral filter mosaics and the colour separating means (123) are suitably spread out in the intervals of a spectrum to be studied. The combination of the colour separating means (123) and the spectral or colour or spectral filter mosaics produces different sets of linearly independent transmission curves (TC). The multiple-filter image captured by the image sensor (12) is demosaicked by identifying and segmenting the image regions that are affected by the regions of the multiple filter mosaic, and after an optional interpolation step, a multi-band image is obtained. The resulting multi-band image is transformed into a multi- or hyperspectral image.

Systems and methods in accordance with embodiments of the invention utilize array cameras incorporating quantum dot color filters. One embodiment includes: lens elements formed on substrates separated by spacers, where the lens elements, substrates and spacers form a plurality of optical channels; at least one aperture located within each optical channel; at least one spectral filter located within each optical channel, where each spectral filter is configured to pass a specific spectral band of light; and at least one quantum dot color filter located within each optical channel to receive the specific spectral band of light passed by the at least one spectral filter located within the optical channel, where the at least one quantum dot color filter is configured to emit a spectral band of light having a bandwidth that is narrower than the specific spectral band of light passed by the at least one spectral filter.

A spectral filtering apparatus and method is presented, which enables the functions of hyperspectral imaging to be performed with increased speed, simplicity, and performance that are required for commercial products. The apparatus includes a photosensitive array having a plurality of photosensitive elements such that different subsections of photosensitive elements of the array receive light of a different wavelength range of a characteristic spectrum of a target, and output electronics combines signals of at least two photosensitive elements in a subsection of the array and outputs the combined signal as a measure of the optical energy within a bandwidth of interest of the characteristic spectrum.

Method and apparatus are contemplated for receiving from an input, an optical signal in a volume hologram comprising a transfer function that may comprise temporal or spectral information, and spatial transformation information; diffracting the optical signal; and transmitting the diffracted optical signal to an output. A plurality of inputs and outputs may be coupled to the volume hologram. The transformation may be a linear superposition of transforms, with each transform acting on an input signal or on a component of an input signal. Each transform may act to focus one or more input signals to one or more output ports. A volume hologram may be made by various techniques, and from various materials. A transform function may be calculated by simulating the collision of a design input signal with a design output signal.

The invention discloses a laser three-dimensional imaging device based on a single-photon detector, belonging to the technical field of photoelectric instruments. A target to be detected is irradiated by the laser pulse emitted by a pulsed laser via a scanning system; the returning photons are received by a receiving / emitting co-axial optical system, i.e., the returning photons are received by a double-gating single-photon detecting module via a spectral filter and a spatial filter and an arriving pulse is outputted, so that the photon flight time of the target measuring point can be measured by combining the laser emission detection and the multi-photon arriving pulse time; and a data processing unit is used for carrying out the coordinate conversion based on the position and attitude data, scanning mirror targeting data, and photon flight time of the three-dimensional imaging device, de-noising and three-dimensional image construction and correction, so as to output the reliable target three-dimensional range image. The invention solves the problems that the existing laser three-dimensional imaging device is incapable of penetrating vegetation and camouflage and being miniaturized when conducting long-distance operations.

A method and system for identifying, tracking, and / or authenticating objects that is simple to apply and to use by an intended user, but is extremely difficult to counterfeit or compromise by an unintended user. Also disclosed is a multi-color, co-planar indicium made of a combination of printed patterns of multiple inks. The printed patterns may be modified by software-generated masks to ensure that the patterns are co-planar. The indicium is undecipherable unless irradiated with specified wavelengths of light radiation, filtered through specified spectral filters, and read and decoded by an electronic image reader. The indicium may be visible or covert. The indicium encodes unique true information about the object and may encode nonsensical or intentionally incorrect information as a further deterrent to unauthorized use. The method permits the indicia to be applied to objects at high processing speeds possible with inkjet printing.

Systems and methods in accordance with embodiments of the invention utilize array cameras incorporating quantum dot color filters. One embodiment includes: lens elements formed on substrates separated by spacers, where the lens elements, substrates and spacers form a plurality of optical channels; at least one aperture located within each optical channel; at least one spectral filter located within each optical channel, where each spectral filter is configured to pass a specific spectral band of light; and at least one quantum dot color filter located within each optical channel to receive the specific spectral band of light passed by the at least one spectral filter located within the optical channel, where the at least one quantum dot color filter is configured to emit a spectral band of light having a bandwidth that is narrower than the specific spectral band of light passed by the at least one spectral filter.

A novel method for high power optical amplification of ultrashort pulses in IR wavelength range (0.7-20 Ãm) is disclosed. The method is based on the optical parametric chirp pulse amplification (OPCPA) technique where a picosecond or nanosecond mode locked laser system synchronized to a signal laser oscillator is used as a pump source or alternatively the pump pulse is created from the signal pulse by using certain types of optical nonlinear processes described later in the document. This significantly increases stability, extraction efficiency and bandwidth of the amplified signal pulse. Further, we disclose five new practical methods of shaping the temporal and spatial profiles of the signal and pump pulses in the OPCPA interaction which significantly increases its efficiency. In the first, passive preshaping of the pump pulses has been made by a three wave mixing process separate from the one occurring in the OPCPA. In the second, passive pre-shaping of the pump pulses has been made by spectral filtering in the pump mode-locked laser or in its amplifier. In the third, the temporal shape of the signal pulse optimized for OPCPA interaction has been actively processed by using an acousto-optic programmable dispersive filter (Dazzler) or liquid crystal light modulators. In the fourth alternative method, the signal pulse intensity envelope is optimized by using passive spectral filtering. Finally, we disclose a method of using pump pulses which interact with the seed pulses with different time delays and different angular orientations allowing the amplification bandwidth to be increased. In addition we describe a new technique for high power IR optical beam delivery systems based on the microstructure fibres made of silica, fluoride or chalcogenide glasses as well as ceramics. Also we disclose a new optical system for achieving phase matching geometries in the optical parametric interactions based on diffractive optics. All novel methods of the ultrashort optical pulse amplification described in this disclosure can be easily generalized to other wavelength ranges.

A wafer-scale apparatus and method is described for the automation of forming, aligning and attaching two-dimensional arrays of microoptic elements on semiconductor and other image display devices, backplanes, optoelectronic boards, and integrated optical systems. In an ordered fabrication sequence, a mold plate comprised of optically designed cavities is formed by reactive ion etching or alternative processes, optionally coated with a release material layer and filled with optically specified materials by an automated fluid-injection and defect-inspection subsystem. Optical alignment fiducials guide the disclosed transfer and attachment processes to achieve specified tolerances between the microoptic elements and corresponding optoelectronic devices and circuits. The present invention applies to spectral filters, waveguides, fiber-optic mode-transformers, diffraction gratings, refractive lenses, diffractive lens / Fresnel zone plates, reflectors, and to combinations of elements and devices, including microelectromechanical systems (MEMS) and liquid crystal device (LCD) matrices for adaptive, tunable elements. Preparation of interfacial layer properties and attachment process embodiments are taught.

The present invention features incorporating an adaptive spectral filter into a confocal scanner optical arrangement or other suitable optical device to permit real time control of the fluorescence signal spectrum being monitored. This new arrangement would allow for better balancing of the fluorescence signals in the analysis of the array.

An element-specific imaging technique utilizes the element-specific fluorescence X-rays that are induced by primary ionizing radiation. The fluorescence X-rays from an element of interest are then preferentially imaged onto a detector using an optical train. The preferential imaging of the optical train is achieved using a chromatic lens in a suitably configured imaging system. A zone plate is an example of such a chromatic lens; its focal length is inversely proportional to the X-ray wavelength. Enhancement of preferential imaging of a given element in the test sample can be obtained if the zone plate lens itself is made of a compound containing substantially the same element. For example, when imaging copper using the Cu La spectral line, a copper zone plate lens is used. This enhances the preferential imaging of the zone plate lens because its diffraction efficiency (percent of incident energy diffracted into the focus) changes rapidly near an absorption line and can be made to peak at the X-ray fluorescence line of the element from which it is fabricated. In another embodiment, a spectral filter, such as a multilayer optic or crystal, is used in the optical train to achieve preferential imaging in a fluorescence microscope employing either a chromatic or an achromatic lens.

Techniques for providing spectroscopic imaging integrates an acousto-optic tunable filter (AOTF), or an interferometer, and a focal plane array detector. In operation, wavelength selectivity is provided by the AOTF or the interferometer. A focal plane array detector is used as the imaging detector in both cases. Operation within the ultraviolet, visible, near-infrared (NIR) spectral regions, and into the infrared spectral region, is achieved. The techniques can be used in absorption spectroscopy and emission spectroscopy. Spectroscopic images with a spectral resolution of a few nanometers and a spatial resolution of about a micron, are collected rapidly using the AOTF. Higher spectral resolution images are recorded at lower speeds using the interferometer. The AOTF technique uses entirely solid-state components and requires no moving parts. Alternatively, the interferometer technique employs either a step-scan interferometer or a continuously modulated interferometer.

A two-dimensional focal plane array (FPA) is divided into sub-arrays of rows and columns of pixels, each sub-array being responsive to light energy from a target object which has been separated by a spectral filter or other spectrum dividing element into a predetermined number of spectral bands. There is preferably one sub-array on the FPA for each predetermined spectral band. Each sub-array has its own read out channel to allow parallel and simultaneous readout of all sub-arrays of the array. The scene is scanned onto the array for simultaneous imaging of the terrain in many spectral bands. Time Delay and Integrate (TDI) techniques are used as a clocking mechanism within the sub-arrays to increase the signal to noise ratio (SNR) of the detected image. Additionally, the TDI length (i.e., number of rows of integration during the exposure) within each sub-array is adjustable to optimize and normalize the response of the photosensitive substrate to each spectral band. The array provides for parallel and simultaneous readout of each sub-array to increase the collection rate of the spectral imagery. All of these features serve to provide a substantial improvement in the area coverage of a hyperspectral imaging system while at the same time increasing the SNR of the detected spectral image.

A tunable optical filter is provided that includes an array of independently tunable filter elements. Each of the elements is located along a different optical path that extends between an input and an output port. Optical assemblies for receiving an incident optical signal for providing a filtered optical signal are also provided. In one embodiment, polarization independent spectral filtering can be achieved. Wavelength selectable add / drop multiplexers and demultiplexers, dynamic gain equalizers and attenuators, optical channel blockers and branch filters, switches, and modulators are also provided. Furthermore, methods for constructing and operating filters consistent with this invention are also provided.

PCT No. PCT / RU97 / 00278 Sec. 371 Date Jul. 9, 1998 Sec. 102(e) Date Jul. 9, 1998 PCT Filed Sep. 3, 1997 PCT Pub. No. WO98 / 28643 PCT Pub. Date Jul. 2, 1998The invention relates to fiber optics and can be employed in fiber radiation collimators, optical waveguide couplers, spectral filters, optical isolators, long-period gratings, dispersion compensators, cascade mode field diameter conversion fibers on simulated Raman effect, physical value sensors, radiation suppression units for predetermined wavelengths, and for smoothing the gain spectrum in erbium fiber amplifiers. The invention facilitates fabrication of optical waveguides and apparatuses based on them. To produce preforms for optical waveguides (1) by a plasma chemical vapor deposition method, molecular gaseous agents, fed to a substrate tube (24), are mixed so that less than five atoms of oxygen fall on every atom of silicon and more than one atom of nitrogen falls on every 1000 atoms of oxygen. The refractive index is locally changed by heating a length of an optical waveguide (1). This causes a local thermal diffusion of elements contained in a core (3) into a cladding (2), or vice versa. The length of the optical waveguide (1) is heated by current of an electric arc (10) or by radiation (16) of an infrared laser (15). The core (3) is doped with nitrogen at concentration from 0.01 at. % to 5 at. %. In the mode field diameter conversion fiber, a diameter of the core (3) changes along the length of the optical waveguide (1), increasing towards its end (4).

An improved sensor (102) for hydration monitoring in mobile devices, wearables, security, illumination, photography, and other devices and systems uses an optional phosphor-coated broadband white LED (103) to produce broadband light (114), which is then transmitted along with any ambient light to target (125) such as the ear, face, or wrist of a living subject. Some of the scattered light returning from the target to detector (141) is passed through a narrowband spectral filter set (155) to produce multiple detector regions, each sensitive to a different waveband wavelength range, and the detected light is spectrally analyzed to determine a measure of hydration, such as fluid losses, fluid ingested, fluid balance, or rate of fluid loss, in part based on a noninvasive measure of components of the bloodstream. In one example, variations in components of the bloodstream over time such as hemoglobin and water are determined based on the detected light, and the measure of hydration is then determined based on the in components of the bloodstream over time. In the absence of the LED light, ambient light may be sufficient illumination for analysis. The same sensor can provide identifying features of type or status of a tissue target, such as heart rate or heart rate variability, respiratory status, or even confirmation that the tissue is alive. Hydration monitoring systems incorporating the sensor, as well as methods, are also disclosed.

This invention relates to an optical fibre that comprises a core (4) of lower refractive index that is surrounded by a cladding which includes regions of a higher refractive index and is substantially periodic, where the core (4) has a longest transverse dimension that is longer than a single, shortest period of the cladding. In a fibre of this type light is substantially confined to the core area by virtue of the photonic band gap of the cladding material. The invention also relates to a method of manufacturing such an optical fibre, comprising the steps of forming a stack of canes (5), the stack (5) including at least one truncated cane (6) that defines an aperture (7), and then drawing the stack (5) into a fibre having an elongate cavity. The fibre is suitable for high power uses, but is equally suitable for other areas, e.g. optical amplifiers, spectral filters, lasers, gas sensors and telecommunications networks.

In one embodiment of the invention, a transmitting spectral filter includes a thin film layer and a grating structure. The thin film layer is made of transmitting material to transmit a first incident radiation within a first band around a first wavelength. The first incident radiation is reflected from a mirror in an optical path. The grating structure is deposited on the thin film layer and is etched to have a grating period. The grating period causes transmission of the first incident radiation within the first band and causes at least one of reflection and diffraction of the second incident radiation above a second wavelength out of the optical path.

The present invention features a fiber optic imaging system for generating a customized spectral response comprising (a) an optional optical source for generating optical energy, (b) an optical system for focusing multi spectral optical energy to form a focal surface; (b) a fiber optic element for conveying the optical energy, wherein the fiber optic element has an input end optically coupled to the focal surface to receive the optical energy and an output end to transmit the conveyed optical energy; and (c) a spectral filter optically coupled to at least one of the input and output ends of the fiber optic element, wherein the spectral filter has a filter passband configured to provide the fiber optic element with a pre-determined wavelength transmittance capacity, such that only pre-determined wavelengths of the optical energy are transmitted through the output end, thus achieving a customized spectral response. The fiber optic imaging system may further comprise an imaging array optically coupled to the output end of the fiber optic element and configured to gather the transmitted optical energy and to convert it into a data signal corresponding to an image based on the customized spectral response. An example of this type of configuration is a spectrometer.

The UV, deep UV and / or far UV (ultraviolet) filter transmission spectrum of an MPSi spectral filter is optimized by introducing at least one layer of substantially transparent dielectric material on the pore walls. Such a layer will modify strongly the spectral dependences of the leaky waveguide loss coefficients through constructive and / or destructive interference of the leaky waveguide mode inside the layer. Increased blocking of unwanted wavelengths is obtained by applying a metal layer to one or both of the principal surfaces of the filter normal to the pore directions. The resulting filters are stable, do not degrade over time and exposure to UV irradiation, and offer superior transmittance for use as bandpass filters. Such filters are useful for a wide variety of applications including but not limited to spectroscopy and biomedical analysis systems.