Patents:


7,593,835 Reformulated atmospheric band model method for modeling atmospheric propagation at arbitrarily fine spectral resolution and expanded capabilities.
A radiative transport band model method for prediction and analysis of high spectral resolution radiometric measurements, Atomic and molecular line center absorption is determined from finite spectral bin equivalent widths.  A mathematically exact expansion for finite bin equivalent widths provides a high accuracy at any desired spectral resolution.  The temperature and pressure dependent Voight line tail spectral absorption contributing to each spectral bin is pre-computed and fit to Padé approximants for rapid and accurate accounting of neighboring-to-distant lines.  A Specific embodiment has been incorporated into the MODTRAN®radiation transport model.

7,680,337 Process for finding endmembers in a data set.
The invention provides a method for identifying one or more materials in a scene by determining a set of spectral vectors, called endmembers, from a data set comprised of spectra from the image data, and matching the set of endmembers to predefined library materials. The image data of the scene is captured with a sensor, and comprises a plurality of spectra. The method applies the iterative mathematical criterion, termed residual minimization, to find the endmembers. The first endmember may be selected based on the largest mean square value or the largest mean magnitude value.  Subsequent endmembers are determined by calculating weighting factors, such that the weighting factors are non-negative and the calculated vector differences, or residuals, generate the smallest error metric. The error metric is dependent upon the vector difference between two spectra in the image data set and may be the mean squared vector differences between two spectra.

7,337,065 Methods for atmospheric correction of solar-wavelength hyperspectral imagery over land.
This invention discloses several improved methods of correcting for atmospheric effects on a remote image of the Earth's surface taken from above, wherein the image comprises a number of simultaneously acquired images of the same scene, each including a large number of pixels, each at a different wavelength band, and including infrared through ultraviolet wavelengths. One method is for retrieving the aerosol/haze amount (i.e., visible range) from an assumed ratio of in-band reflectances, rather than from an assumed reflectance value. Another method is for identifying cloud-containing pixels. This is used to improve the calculation of the spatially averaged radiance L*.sub.e and reflectance .rho..sub.e images in standard equations. Another method greatly reduces the number of mathematical operations required to generate the reflectance values. This method operates by averaging the water vapor and .rho..sub.e values over small groups of neighboring pixels, so that the same A, B, S, L*.sub.a parameter values may also be assigned to all pixels within the group. Yet another new method accounts for shifts in the wavelength calibration within the image, such as would be caused by spectral "smile". This method loops the calculation of A, B, S and L*.sub.a over a set of possible wavelength shifts with respect to the input channel centers, and assigns the appropriate set of parameters to each pixel based on a pixel-location-dependent formula for the wavelength shift.

7,324,196 Spectral encoder.
A spectral encoder for producing spectrally selected images of radiation field containing multiple spectral components. An imaging spectrograph defines a first optical path that produces from the input radiation field a spectrally dispersed image comprising multiple spectral components displaced along a dispersion direction. Spectral pass bands are encoded on the dispersed image by a programmable spatial light modulator using one or more spatial mask.  The imaging spectrograph further defines a second optical path that reverses the spectral dispersion of the first path and produces a spectrally-encoded polychromatic output image containing only those spectral components encoded by the spatial mask.  The first and second optical paths share a common dispersing element. A detector records at least one spatial region of the spectrally encoded output image.

7,046,859 Methods for determining a measure of atmospheric aerosol optical properties using a multi- or hyperspectral, multi-pixel image.
A method of automatically determining a measure of atmospheric aerosol optical properties using a multi- or hyper-spectral, multi-pixel image.  A plurality of spectrally-diverse pixels are resolved from the image. A statistical spectral deviation of the spectrally-diverse pixels is determined and then corrected for non-aerosol transmittance losses.  One or more wavelength-dependent aerosol optical depths are derived from the statistical spectral deviation. Wavelength-dependent gaseous optical depths can be derived from the statistical spectral deviation.

6,909,815 Method for performing automated in-scene based atmospheric compensation for multi-and hyperspectral imaging sensors in the solar reflective spectral region.
A method of automatically compensating of multi- or hyper-spectral, multi-pixel image for atmospheric effects, compromising revolving a plurality of spectrally diverse pixels from the image, determining a statistical spectral deviation of the spectrally-diverse pixels, normalizing the statistical spectral deviation by applying a scale factor, and compensating image pixels with both the spectral baseline and the normalized spectral deviation. Another embodiment features a method of automatically determining a measure of atmospheric aerosol optical properties using a multi- or hyper-spectral, multi-pixel image, comprising resolving a plurality of spectrally-diverse pixels from the image, determining a statistical spectral deviation of the spectrally-diverse pixels, correcting the statistical spectral deviation for non-aerosol transmittance losses, and deriving from the statistical spectral deviation of the spectrally-diverse pixels, correcting the statistical spectral deviation for non-aerosol transmittance losses, and deriving from the statistical spectral deviation one or more wavelength-dependent aerosol optical depths. A final embodiment features a method of automatically determining a measure of atmospheric gaseous optical properties using a multi- or hyper-spectral, multi-pixel image, compromising resolving a plurality of spectrally-diverse pixels from the image, determining a statistical spectral deviation of the spectrally-diverse pixels, and deriving from the statistical spectral deviation wavelength-dependent gaseous optical depths.

6,640,199 System and Method for Optically Determining Properties of Hot Fluids from the Spectral Structure Of Emitted Radiation.
A system and method for remotely determining at least one of the temperature of, and the relative concentrations of species making up, a hot fluid, based on the spectral structure of radiation emitted from the fluid. Thermal radiation over a field of view including the hot fluid is collected. At least a portion of the emission spectrum from the collected radiation is resolved. The resolved emission spectrum is resolved into spectra that are characteristic of specific emitting species and emitter temperatures. The temperature of, and the relative concentrations of species making up, the hot fluid, are determined from the relative amounts of at least two resolved spectra.

6,066,295 System and Method for Remote Detection and Remediation of Airborne and Waterborne Chemical/Biological Agents.
A method and device for remotely analyzing an agent dispersed in the atmosphere is disclosed in which a body is dispensed into a volumetric region of the atmosphere overlapping the region containing the agent. The body is tailored to induce changes in an electromagnetic response of the volumetric region including the agent due to body the reactive probe and the agent. By sensing electromagnetic radiation from the region, information may be gained concerning the agent based upon the new electromagnetic response of the volumetric region induced by the reactions. Since a probe is used, source need not be known, and the electromagnetic signature may be tailored to atmospheric and device limitations.

5,822,058 Systems and Methods for Optically Measuring Gases
A system and method for optical interrogation and measurement of a hydrocarbon fuel gas includes a light source generating light at near-visible wavelengths. A cell containing the gas is optically coupled to the light source which is in turn partially transmitted by the sample. A spectrometer disperses the transmitted light and captures an image thereof. The image is captured by a low-cost silicon-based two-dimensional CCD array. The captured spectral image is processed by electronics for determining energy or BTU content and composition of the gas. The innovative optical approach provides a relatively inexpensive, durable, maintenance-free sensor and method which is reliable in the field and relatively simple to calibrate. In view of the above, accurate monitoring is possible at a plurality of locations along the distribution chain leading to more efficient distribution.

5,459,574 Off-Line-Locked Laser Diode Species Monitor System
An off-line-locked laser diode species monitor system includes: reference means for including at least one known species having a first absorption wavelength; a laser source for irradiating the reference means and at least one sample species having a second absorption wavelength differing from the first absorption wavelength by a predetermined amount; means for locking the wavelength of the laser source to the first wavelength of the at least one known species in the reference means; a controller for defeating the means for locking and for displacing the laser source wavelength from said first absorption wavelength by said predetermined amount to the second absorption wavelength; and a sample detector device for determining laser radiation absorption at the second wavelength transmitted through the sample to detect the presence of the at least one sample species.

5,485,276 Multi-pass Optical Cell Species Concentration Measurement System
A multi-pass optical cell for measuring the concentration of one or more species in a fluid to be monitored includes a sample region; a source of collimated radiation; a detector device for sensing the intensity of the radiation; at least two reflective surfaces for reflecting in a first direction in the sample region a number of times the radiation from the source and delivering it to the detector device.

5,026,991 Gaseous Species Absorption Monitor
A wavelength-locked laser gaseous species monitor including a variable wavelength laser with a laser output actively stabilized to a wavelength at or near an absorption wavelength of the species being monitored. The laser is modulated about that wavelength to establish a modulated output with a known frequency and bandwidth. The modulated output is passed through the sample being monitored and then collected. An even harmonic of the collected output with respect to the modulation frequency is determined, and the presence in the sample of the species being monitored is detected from the even harmonic signal.

4,953,976 Gas Species Monitor System
A gas species monitor system includes a sample volume for receiving a gas to be monitored; an external, independent laser source; means for directing the laser radiation to the volume; a multipass optical cell, responsive to the means for directing, for multiplying the laser radiation intensity in the sample volume; means for continuously flowing the gas to be monitored through the sample volume; a narrow bandpass filter; means for collecting more than a steradian of Raman scattered radiation from the sample in the volume and directing the collected radiation in parallel through the narrow bandpass filter; and means responsive to the parallel radiation from the filter for detecting the Raman scattered radiation representative of the concentration of the species in the gas sample being monitored.

4,782,232 Infrared Molecular Species Monitor
An infrared monitor for measuring the presence of at least one gas phase molecular species including a sample path for containing a sample to be monitored for the molecular species. A sample beam of infrared source emission of the molecular species to be monitored for passage through the sample path is provided to the sample path. The sample beam includes at least one primary spectral emission line which is significantly absorbed by the molecular species. The decrease in the intensity of the at least one primary infrared source spectral emission line passing through the sample path is detected as a function of the absorption of the at least one line by the molecular species present in the sample

4,780,613 Infrared Species-Specific Emission Source
An infrared species specific emission source which includes a closed container having at least one transparent portion for containing at least one specific molecular species. The molecular species within the container is heated sufficiently to cause the species to emit a characteristic infrared spectral emission through the at least one transparent portion of the container to the infrared instrument.