Mid-Infrared Standoff Spectroscopy Using a Supercontinuum Laser with Compact Fabry–Pérot Filter Spectrometers

Abstract

Mid-infrared (MIR) supercontinuum (SC) lasers are an attractive new option in the field of IR spectroscopy, especially for standoff detection. Supercontinuum radiation unites high brightness, high spatial coherence, and broadband spectral coverage, thereby surpassing thermal IR sources and challenging quantum cascade lasers. The employed SC source operates in the spectral region of 1.2-4.6 µm, filling the spectral gap where quantum cascade lasers lack broader availability. In this work, the SC radiation was recorded by compact Fabry-Pérot filter spectrometers ideally suited for sensitive standoff detection with real-time capability. The noise performance of the setup and measurements of different substances at standoff distances are presented, e.g., of different paints on a metal surface and an explosive precursor. Furthermore, the real-time capability of the setup is demonstrated by monitoring the evaporation of liquid 2-propanol.

Review of Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy (IBBCEAS) for Gas Sensing

“…The supercontinuum radiation source which outperforms conventional thermal sources in terms of brightness and collimation is of particular interest for trace gas sensing where strong mid-IR absorption bands associated with fundamental vibrational transitions can be measured [ 91 ]. Further improvements of output powers and spectral flux stability of SC light sources enable the application of mid-IR absorption spectroscopy without the use of expensive mid-IR lasers (e.g., quantum cascade laser, interband cascade laser) [ 101 ].…”

Application of a Novel Low-Cost Hyperspectral Imaging Setup Operating in the Mid-Infrared Region

“…This indicates the importance of the optical design and the sample illumination. Depending on the specific demands of the application, the illumination can also be executed by newly available MIR laser-based light sources such as quantum cascade lasers [5] or supercontinuum lasers [6]. For the first time hyperspectral imaging in the decisive fingerprint region was realized to be low-cost and small-sized.…”

A pocket-sized 3D-printed attenuated total reflection-infrared filtometer combined with functionalized silica films for nitrate sensing in water

“…27 A micro-electro-mechanical system (MEMS)-based mid IR filter using a FP air resonator combined with a pyroelectric detector was first reported in 2003 and is now commercially distributed in several MIR wavelength ranges. 28,29 FP filterdetectors have been successfully paired with miniaturized pulsed MIR emitters were employed for process gas monitoring in transmission gas cells, [30][31][32] for liquid sensing, 33 imaging systems 34 as well as paired with a supercontinuum laser for standoff IR spectroscopy. 32 These reports achieved adequate analytical performance without the high spectral resolution and the full spectral coverage provided by FTIR spectrometers while reducing the costs and size of the respective sensing system.…”