Division of Atomic Physics, Department of Physics, Lund University, SE-221 00 Lund, Sweden.
Opt Lett. 2011 Aug 15;36(16):3036-8. doi: 10.1364/OL.36.003036.
Simultaneous assessment of the spectroscopic absorption signal of gas enclosed in a scattering medium and the corresponding optical path length of the probing light is demonstrated using a single setup. Sensitive gas absorption measurements are performed by a tunable diode laser using wavelength-modulation spectroscopy, while the path length is evaluated by the frequency-modulated cw technique commonly used in the field of telecommunication. Proof-of-principle measurements are demonstrated with water vapor as the absorbing gas and using polystyrene foam as an inhomogeneously scattering medium. The combination of these techniques opens up new possibilities for straightforward evaluation of gas presence and exchange in scattering media.
本文提出了一种利用单一设置同时评估封闭在散射介质中的气体的光谱吸收信号和探测光的相应光程的方法。可调谐二极管激光采用波长调制光谱法进行灵敏的气体吸收测量，而路径长度则通过在电信领域常用的调频连续波技术进行评估。实验中以水蒸气作为吸收气体，以聚苯乙烯泡沫作为非均匀散射介质，验证了这一原理。这两种技术的结合为在散射介质中直接评估气体的存在和交换开辟了新的可能性。
