Pinto Davide, Moser Harald, Waclawek Johannes P, Dello Russo Stefano, Patimisco Pietro, Spagnolo Vincenzo, Lendl Bernhard
Institute of Chemical Technologies and Analytics, Technische Universität Wien, Getreidemarkt 9/164, 1060 Vienna, Austria.
PolySense Lab - Dipartimento Interateneo di Fisica, University and Politecnico of Bari, Via Amendola 173, Bari, Italy.
Photoacoustics. 2021 Feb 1;22:100244. doi: 10.1016/j.pacs.2021.100244. eCollection 2021 Jun.
We report on a comparison between two optical detection techniques, one based on a Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) detection module, where a quartz tuning fork is acoustically coupled with a pair of millimeter-sized resonator tubes; and the other one based on a Photothermal Spectroscopy (PTS) module where a Fabry-Perot interferometer acts as transducer to probe refractive index variations. When resonant optical absorption of modulated light occurs in a gas sample, QEPAS directly detects acoustic waves while PTS probes refractive index variations caused by local heating. Compact QEPAS and PTS detection modules were realized and integrated in a gas sensor system for detection of carbon monoxide (CO), targeting the fundamental band at 4.6 μm by using a distributed-feedback quantum cascade laser. Performance was compared and ultimate detection limits up to ∼ 6 part-per-billion (ppb) and ∼15 ppb were reached for QEPAS and the PTS module, respectively, using 100 s integration time and 40 mW of laser power.
我们报告了两种光学检测技术之间的比较，一种基于石英增强光声光谱（QEPAS）检测模块，其中石英音叉与一对毫米尺寸的谐振管声学耦合；另一种基于光热光谱（PTS）模块，其中法布里-珀罗干涉仪用作换能器来探测折射率变化。当调制光在气体样品中发生共振光吸收时，QEPAS直接检测声波，而PTS探测由局部加热引起的折射率变化。实现了紧凑的QEPAS和PTS检测模块，并将其集成到用于检测一氧化碳（CO）的气体传感器系统中，通过使用分布反馈量子级联激光器针对4.6μm的基频带。比较了性能，使用100秒积分时间和40毫瓦激光功率时，QEPAS和PTS模块分别达到了高达约6十亿分之一（ppb）和约15 ppb的最终检测限。
