A miniaturized hyperspectral imager is enabled with image sensor integrated with dispersing elements in a very compact
form factor, removing the need for expensive, moving, bulky and complex optics that have been used in conventional
hyperspectral imagers for decades. The result is a handheld spectral imager that can be installed on miniature UAV
drones or conveyor belts in production lines. Eventually, small handhelds can be adapted for use in outpatient medical
clinics for point-of-care diagnostics and other in-field applications.
The requirements for standoff detection of Explosives and CWA/TICs on surfaces in the battlefield are challenging because of the low detection limits. The variety of targets, backgrounds and interferences increase the challenges. Infrared absorption spectroscopy with traditional infrared detection technologies, incandescent sources that offer broad wavelength range but poor spectral intensity, are particularly challenged in standoff applications because most photons are lost to the target, background and the environment. Using a brighter source for active infrared detection e.g. a widely-tunable quantum cascade laser (QCL) source, provides sufficient spectral intensity to achieve the needed
sensitivity and selectivity for explosives, CWAs, and TICs on surfaces. Specific detection of 1-10 μg/cm2 is achieved
within seconds. CWAs, and TICs in vapor and aerosol form present a different challenge. Vapors and aerosols are present at low
concentrations, so long pathlengths are required to achieve the desired sensitivity. The collimated output beam from the
QCL simplifies multi-reflection cells for vapor detection while also enabling large standoff distances. Results obtained by the QCL system indicate that <1 ppm for vapors can be achieved with specificity in a measurement time of seconds, and the QCL system was successfully able to detect agents in the presence of interferents. QCLs provide additional capabilities for the dismounted warfighter. Given the relatively low power consumption, small package, and instant-on capability of the QCL, a handheld device can provide field teams with early detection of toxic agents and energetic materials in standoff, vapor, or aerosol form using a single technology and device which makes it attractive compared other technologies.
Block Engineering has developed a widely tunable quantum cascade laser (QCL) spectrometer, a probe, and algorithms
specific to detecting low levels of surface contamination. This paper discusses the basic technology of the QCL
spectrometer both in a standoff and probe based configuration. It provides information on the algorithms and probes
developed for this application. The paper compares the QCL based technique to other approaches for detecting surface
contamination.
Block Engineering has developed an absorption spectroscopy system based on widely tunable Quantum Cascade Lasers
(QCL). The QCL spectrometer rapidly cycles through a user-selected range in the mid-infrared spectrum, between 6 to
12 μm (1667 to 833 cm-1), to detect and identify substances on surfaces based on their absorption characteristics from a standoff distance of up to 2 feet with an eye-safe laser. It can also analyze vapors and liquids in a single device. For
military applications, the QCL spectrometer has demonstrated trace explosive, chemical warfare agent (CWA), and toxic
industrial chemical (TIC) detection and analysis.
The QCL's higher power density enables measurements from diffuse and highly absorbing materials and substrates.
Other advantages over Fourier Transform Infrared (FTIR) spectroscopy include portability, ruggedness, rapid analysis,
and the ability to function from a distance through free space or a fiber optic probe. This paper will discuss the basic
technology behind the system and the empirical data on various safety and security applications.
Rapid quantitative imaging of chemical species is an important tool for investigating heterogenous mixtures, such as laminated plastics, biological samples and vapor plumes. Using traditional spectroscopic methods requires difficult computations on very large data sets. By embedding a spectral pattern that corresponds to a target analyte in an interference filter in a beamsplitter arrangement; the chemical information in an image can be obtained rapidly and with a minimal amount of computation. A candidate filter design that is tolerant to the angles present in an imaging arrangement is evaluated in near-infrared spectral region for an organic analyte and an interferent.
Quantitative multivariate spectroscopic methods seek spectral patterns that correspond to analyte concentrations even in the presence of interferents.By embedding a spectral pattern that corresponds to a target analyte in an interference filter in a beamsplitter arrangement;bulky and complex instrumentation can be eliminated with the goal of producing a field-portable instrument.A candidate filter design for an rganic analyte,of military interest,and an interferent is evaluated.
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