Society of Photo-optical Instrumentation Engineers, Proceedings of SPIE, 2013
DOI: 10.1117/12.2033620
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We report on an innovative quartz enhanced photoacoustic (QEPAS) gas sensor operating in the THz spectral range, emp loying a custom quartz tuning fork (QTF) with the two prongs spaced by ~800 μm. To test our sensor we employed a quantum cascade laser light source and selected a methanol rotational absorption line falling at 131.054 cm −1 (~3.93 THz), with line-strength S = 4.28·10 -21 cm. The sensor operated at 10 Torr p ressure on the QTF first flexion resonance frequency at 4245 Hz. We achieved a QEPAS normalized noise-equivalent absorption of 2·10 -10 W·cm -1 ·Hz -1/2 comparable with the best result of mid-IR QEPAS systems.