Portable open-path chemical sensor using a quantum cascade laser

Corrigan, Paul; Lwin, Maung; Huntley, Reuven; Chhabra, Amandeep; Moshary, Fred; Gross, Barry; Ahmed, Samir

doi:10.1117/12.820687

Cited by 4 publications

(2 citation statements)

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“…However, FTIR measurements are larger than QCL measurements for sanded aluminum surfaces which may be the results of strong water vapor absorbance near 5µm and geometric errors in experimental setup. We applied the above results to an open-path chemical sensor model, called link-power analysis, which was explained detail in our previous paper [1]. In link-power analysis, optical efficiency (η) can be calculated from total power attenuation (α tot ) due to atmosphere conditions and sensor system components, relative power gain (γ tot ), receiver and link parameters (surface albeto β, and solid angle Ω)as shown in equation (3).…”

Section: Resultsmentioning

confidence: 98%

“…In Lambertian (diffuse) reflection, under normal illumination, the scattered light is a function of the angle between the surface normal and observer's line of sight and can be stated as (1) where I θ is reflected intensity, I 0 is reflected intensity normal to the surface and θ is the angle between the observing direction and normal to the surface. In reality, no surface is a perfect Lambertian reflector but for sufficiently rough surfaces, the Lambertian model can be used as a first approximation [4].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Mid-infrared backscattering measurements of building materials using a quantum cascade laser

et al. 2010

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Open-path quantum cascade laser (QCL) systems are being developed for remote environmental monitoring applications for detection of small levels of toxins or pollutant gases in ambient air. In monostatic systems that rely on topographic backscatter, the surface reflection of the target becomes important. To address the feasibility of natural targets in an open-path geometry, we present the backscattering measurements of common urban building materials (aluminum, natural stones, ceramic wall tiles and concrete block) using a distributed feedback (DFB) pulsed QCL. Real surface roughness in the materials was taken into account. In particular, oblique scattering cases which are often unavoidable in field measurements were also investigated. The QCL measurements were evaluated with a FTIR system in which wide frequency range (2.8μm -25μm) measurements were possible. These results were applied to a total link model to define the potential and range of an open path QCL chemical sensor system.

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Section: Resultsmentioning

confidence: 98%

Section: Theoretical Backgroundmentioning

confidence: 99%