Abstract: A pseudo-active chemical imaging sensor including irradiative transient heating, temperature nonequilibrium thermal luminescence spectroscopy, differential hyperspectral imaging, and artificial neural network technologies integrated together. The sensor may be applied to the terrestrial chemical contamination problem, where the interstitial contaminant compounds of detection interest (analytes) comprise liquid chemical warfare agents, their various derivative condensed phase compounds, and other material of a life-threatening nature. The sensor measures and processes a dynamic pattern of absorptive-emissive middle infrared molecular signature spectra of subject analytes to perform its chemical imaging and standoff detection functions successfully.

Abstract: A system, apparatus, and method of generating Stokes vectors, a Mueller matrix, and polarized scattering from an aerosol aggregate includes providing an incident infrared laser beam; causing the incident infrared laser beam to be polarization-modulated using variable stress/strain birefringence imposed on a ZnSe crystal; defining a Stokes vector associated with the incident infrared laser beam; scattering the incident infrared laser beam from an aggregate aerosol comprising interferents and analyte particles; producing a scattered-beam reactant Stokes vector by causing the scattered incident infrared laser beam to be polarization-modulated; generating a Mueller matrix by taking a transformation of the Stokes vector; and identifying the analyte using the Mueller matrix. The Mueller matrix may comprise M-elements that are functions of a wavelength of the infrared laser beam, backsattering orientation of the infrared laser beam, and a shape and size of the interferents and analyte particles.

Abstract: An optomechanical switching device, a control system, and a graphical user interface for a photopolarimetric lidar standoff detection that employs differential-absorption Mueller matrix spectroscopy. An output train of alternate continuous-wave CO2 laser beams [ . . . L1:L2 . . . ] is directed onto a suspect chemical-biological (CB) aerosol plume or the land mass it contaminates (S) vis-à-vis the OSD, with L1 [L2] tuned on [detuned off] a resonant molecular absorption moiety of CB analyte. Both incident beams and their backscattered radiances from S are polarization-modulated synchronously so as to produce gated temporal voltage waveforms (scattergrams) recorded on a focus at the receiver end of a sensor (lidar) system. All 16 elements of the Mueller matrix (Mij) of S are measured via digital or analog filtration of constituent frequency components in these running scattergram data streams (phase-sensitive detection).

Abstract: An analog Mueller matrix data acquisition system (AMMS) acquiring middle-infrared Mueller (M) matrices of backscattering surfaces. The M-elements are measured by means of an active photopolarimetric sensor. The AMMS records nine M-elements simultaneously in groups of four modulo 2 incident continuous-wave CO2 laser beams—one incident beam is tuned to a fundamental molecular absorption cross-section by the aerosol of detection interest (analytic wavelength ?a) while the other beam is detuned off that resonance band (reference wavelength ?r) and in the closest vicinity to ?a. Accordingly, those ?M elements exhibiting susceptible behavior to the aerosol analyte, driven on-then-off its molecular vibrational resonance band, cues an identification event thus providing detection decision information.

Abstract: A Thermal Luminescent (TL) spectroscopy system and method for remote sensing and detection of surface chemical contamination involves irradiation of a target surface with energy from a near infrared pump beam, and measurement of TL liberated by that surface within a middle infrared (MIR) region. Fundamental molecular vibration modes of target contaminants present are briefly activated after the surface has been driven out of thermal equilibrium. An emissivity contrast between strata and target contaminant develops, peaks, and then subsides during a finite thermal window of detection opportunity in which detection of fingerprint identifiers for target contaminants is most probable. Target contaminant identification employs neural network models trained and tested against known molecular absorption frequencies of target contaminants. The use of a pump beam that radiates energy outside the MIR spectra of received TL reduces possible interference with the very weak MIR signals given off by target contaminants.

Abstract: A passive interferometer chemical sensor and photopolarimeter communicator includes collector and collimator optics, shared solid-state interferometer/photopolarimeter phase-modulation optics, and a lens imager system. The passive interferometer locates, identifies, and tracks an infrared-absorbing vapor in an open panorama by measuring vibration spectrum moiety. The communicator includes a communications beam that is modulated by the shared projected into the same object space from which chemical imaging is preformed. The communications beam provides detection data that is binary encrypted by Mueller matrix-element encoding.

Abstract: A Thermal Luminescence Water Monitor system and method for real-time remote sensing and identification of chemical and biological materials (CBMs) in a liquid source, comprising an irradiation component having a microwave radiation source tuned to water's vibration-rotation exciting energy, a glass cell for holding a liquid sample contained within a sealed chamber for its irradiation and concomitant liberation of thermal luminescence, a spectrometer analysis component for collecting and processing thermal luminescence emissions, a neural network component for filtering thermal luminescence difference-spectra components and pattern recognition of predetermined CBMs to determine their presence in the liquid source.

Abstract: Chemical agent warfare materials and their simulant liquids are identified on terrestrial surfaces at a distance by recognizing the contaminant's infrared fingerprint spectrum brought out in thermal luminescence (TL). Suspect surfaces are irradiated with microwave light that is absorbed into the surface and, subsequently, TL is released by the surface. An optics receiver collects the released TL radiant light, and a data acquisition system searches this TL radiant flux for the contaminant's fingerprint infrared spectrum. A decision on the presence or absence of any-of-N contaminants is done by a neural network system that acts as a filter through real-time pattern recognition of the contaminant's unique infrared absorption or emission spectra.

Abstract: A neural network pattern recognition system for remotely sensing and identifying chemical and biological materials having a software component having an adaptive gradient descent training algorithm capable of performing backward-error-propagation and an input layer that is formatted to accept differential absorption Mueller matrix spectroscopic data, a filtering weight matrix component capable of filtering pattern recognition from Mueller data for specific predetermined materials and a processing component capable of receiving the pattern recognition from the filtering weight matrix component and determining the presence of specific predetermined materials. A method for sensing and identifying chemical and biological materials also is disclosed.

Abstract: An apparatus for remotely sensing and identifying chemical and biological terials comprising an interrogation component having a first and second infrared radiation source providing a predetermined exciting energy and a predetermined referencing energy, a collection component for collecting backscattering radiation, an optical analysis component for converting the collected backscattered radiation into Mueller matrix elements, a filter component for pattern recognition from the Mueller matrix for specific predetermined materials and a comparison component for determining the presence of specific predetermined materials. A method for identifying chemical and biological materials is disclosed.

Abstract: A spectroradiometer for analyzing chemicals located within a panorama comsed of hyperboloid mirrors for directing light received from the panorama through a collimator and via an interferometer to an array of detectors, the signals from which are subjected to parallel discrete Fourier transform and parallel spectra pattern recognition systems. Transmissions of data is achieved by using an interferometer having modulated photoelastic modulators positioned between linear polarizers, directing laser light through the interferometer to the hyperboloid mirrors and providing a receiver comprised of a linear polarizer, a detector, a plurality of band pass amplifiers, and a processor for recognizing the different patterns in the output of the amplifier that result from rotating at least one of the photoelastic modulators and polarizers to a different position.

Abstract: Apparatus for producing interferograms on array of light detectors is described in which light from a field of view is gathered by a concave Newtonian mirror, collimated by a Schwarzchild objective and directed along a first optical path having PEM's modulated so as to act like an interferometer between a pair of linear polarizers and a lens for imaging light passing through said polarizers onto the array. Scattergrams are produced on the array by a laser in a second optical path that includes a linear polarizer, a modulated PEM for producing light that is polarization modulated, optical elements for directing the circularly polarized light into the field of view of the Newtonian mirror, a modulator for causing the PEM's in the first optical path to elliptically polarize light and a device for extracting the first linear polarizer in the first optical path from that path.

Abstract: A four-layer neural network is trained with data of midinfrared absorption by nerve and blister agent compounds (and simulants of this chemical group) in a standoff detection application. Known infrared absorption spectra by these analyte compounds and their computed first derivative are scaled and then transformed into binary or decimal arrays for network training by a backward-error-propagation (BEP) algorithm with gradient descent paradigm. The neural network transfer function gain and learning rate are adjusted on occasion per training session so that a global minimum in final epoch convergence is attained. Three successful neural network filters have been built around an architecture design containing: (1) an input layer of 350 neurons, one neuron per absorption intensity spanning 700.ltoreq..nu..ltoreq.1400 wavenumbers with resolution .DELTA..nu.

Abstract: A system for remotely detecting liquid contaminants on surfaces, including hemical agents and their simulants is presented. The system includes a Fourier Transform Infrared Spectroradiometer aligned to optionally develop graybody photoluminescence spectra from the generation of a plurality of interferograms co-added to provide a favorable signal to noise ratio for use with and thereafter transforming the co-added interferograms. A laser is used for surface irradiating a substrate potentially having the chemical agents to heat the substrate. A shutter controls the laser to receive and record photoluminescence emissions from the heated substrate, and generate a plurality of interferograms co-added to provide a favorable signal to noise ratio for use with the Fourier Transform Infrared Spectroradiometer. The co-added interferograms are used to generate molecular absorption resonant peaks which are mathematically processed in the Fourier Transform Infrared Spectroradiometer.