Mid-infrared DMD-based spectral-coding spectroscopy with a supercontinuum laser source
Paul Gattinger, Ivan Zorin, Alexander Ebner, Christian Rankl, Markus Brandstetter
Abstract
We present a mid-infrared spectroscopic system based on a spectral-coding approach enabled by a modified digital micromirror device (DMD). A supercontinuum source offering a confined mid-infrared laser beam is employed to perform gas measurements with this system. The performance, flexibility, and programmability enabled by the DMD is experimentally demonstrated by gas-cell measurements (CO 2 , CH 4 , N 2 O, NO 2 and CO). Full spectra are acquired in 14 ms at 10 nm spectral resolution and in 3.5 ms at 40 nm spectral resolution. Further, we employ the system for stand-off open-path spatially resolved CO 2 measurements that fully exploit the laser emission properties – the bright and highly-collimated supercontinuum beam is scanned by a galvo mirror over a retroreflector array at a scalable remote distance. The measurement concept models a passing gas emitter under lab conditions; time and spatially resolved CO 2 absorbance gas-plume images in the mid-infrared range are obtained.