Active Mid-Wave to Long-Wave Supercontinuum FTIR Sensor for Standoff Chemical Detection

We demonstrate a prototype mid-wave to long-wave infrared supercontinuum, Fourier transform sensor capable of chemical detection and identification at 3.6 m. The system utilizes a 150 mW supercontinuum source with a continuous spectrum from 1.6-11 μm and an M
²
<; 1.4, from 3 <; λ <; 11 μm, to provide high brightness at the target. We measure scattering spectra from powder particles on soda-lime glass down to a concentration of 7.4 μg/cm
²
and show that they match theoretical spectra simulated via a Bobbert-Vlieger model. Unlike diffuse scattering measurements performed on commercial Fourier transform infrared spectrometers, this standoff sensor collects a numerical aperture of 0.0375 and received powers are four orders of magnitude lower than probe powers.