Photoacoustic gas detection with LED QEPAS

Various configurations and applications have been investigated and realized since the pioneering introduction of quartz-enhanced photoacoustic spectroscopy (QEPAS) by Kosterev et al. in 2002 [1]. However, the required submillimeter diameter of the acoustic resonator demands an excellent beam quality of laser source and precise adjustments of the QEPAS system. In a new approach, the off-beam resonator scheme [2] is proposed for avoiding these demands of conventional QEPAS systems. The positioning of tuning fork within the beam path is no longer necessary (Fig. 1).