Fiber optic coupled quantum cascade infrared laser system for detection of explosive materials on surfaces

The design and assembly of a unique infrared (IR) optical-fiber combined quantum cascade laser (QCL) system is described. This system integrates the output from four individual QCL modules, using infrared optical fibers, into a single output aperture to provide continuous spectral scanning from 6.02 to 11.17 μm. Spectra were collected on a diffuse gold reference as well as multiple concentrations of the explosive 1,3,5-Trinitro-1,3,5-triazinane (RDX) which were inkjet printed on aluminum substrates. The collected RDX spectra were compared to RDX spectra collected using a conventional Fourier-transform infrared spectrometer (FTIR). The results show good agreement between the spectra collected using the fiber-combined QCL system and the standard FTIR.

These results demonstrate that the use of infrared optical fibers to combine multiple QCL modules is a viable approach to developing IR laser sources for use in fieldable devices capable of standoff detection of explosives.