Fast infrared spectrometer for flowing gases by the use of a hollow fiber and a PtSi sensor array

Low-volume, fast response-time hollow silica waveguide gas cells for mid-IR spectroscopy

“…However, the ends of the system were not explicitly coupled to the gas supply and represent potential dead space in the system. Saito and Kato [37] describe a hollow waveguide gas cell with metal holders at each end, which allow gas in and out. The holders house a calcium fluoride (CaF 2 ) window to allow light in and out.…”

Tunable infrared filter made of thin silicon wedges

“…Fabry-Pérot interferometers are therefore used extensively in various technical fields; e.g., diaphragm pressure sensors [1,2], optical communication devices [3][4][5], and laser oscillators [6]. While most experiments on these applications have been conducted in the visible or near-infrared regions, applications to mid-infrared measurements are also attracting interests recently [7][8][9][10], since high-speed, compact, inexpensive spectrometers are required in such advanced infrared measurements as in situ spectrometry and multi-wavelength thermometry [11]. Until now various tuning methods have been proposed for Fabry-Pérot filters [12]; e.g., air compression in a cavity [13], electric reorientation of liquid crystal [4][5][6]14,15], piezoelectric mirror drive [3,7,8,15], and thermal bending of a cantilever [16].…”

Fabrication of Mid-Infrared Tunable Filter with Roughened Silicon Plates

“…However, spectrometers are large and expensive, since they use diffraction gratings [multi-channel charge-coupled device (CCD) spectrometers] or Michelson interferometers (Fourier transform spectrometers). 1,2) These requirements can be satisfied using a tunable Fabry-Perot filter; i.e., an interference filter whose optical thickness nd (n: refractive index, d: cavity length) is changeable. 3) In the visible and near-infrared regions, tunable Fabry-Perot filters were developed using liquid crystals.…”