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.
