551 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 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.

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 imaging system comprises a plurality of spectral units arranged in an array, each spectral unit of the plurality of spectral units comprising: a microlens having an optical axis; a spectral filter having a center wavelength and aligned with the optical axis; a fiber optic bundle, the fiber optic bundle having a curved light receiving surface and a planar light output surface, wherein the curved light receiving surface is aligned with the optical axis; and a plurality of pixel sensors configured to receive light from the planar light output surface of the fiber optic taper portion.

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.

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.

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 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.

The invention is directed to a hyperspectral/multispectral system referred to as the OxyVu-1 system. The hyperspectral imaging technology performs spectral analysis at each point in a two-dimensional scanned area producing an image displaying information derived from the analysis. For the OxyVu-1 system, the spectral analytical methods determined in superficial tissues approximate values of oxygen saturation (HT-Sat), oxyhemoglobin levels (HT-oxy), and deoxyhemoglobin levels (HT-deoxy). The OxyVu-1 system displays the tissue oxygenation in a two-dimensional, color-coded image.

The system contains a system console, a cart, system electronics, CPU, monitor, keyboard, pointing device and printer. The hyperspectral instrument head with support arm contains broadband illuminator, camera and spectral filter for collecting hyperspectral imaging cube. The single use OxyVu Check Pads and Targets are used to perform an instrument check prior to patient measurements. The OxyVu Target is placed within the intended field of view and is used as a fiduciary mark for image registration and for focusing.

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.