QCL-based sensors target health and environmental applications

Some selected examples of recent developments for quartz-enhanced photoacoustic spectroscopy, Faraday rotation spectroscopy, a QCL open-path system, and a wireless sensor network over Princeton, are presented. A novel and recently much improved approach to using quartz-enhanced photoacoustic spectroscopy (QEPAS) is to accumulate the acoustic energy in a sharply resonant acoustic transducer in the form of a quartz tuning fork. The QEPAS technique has many unique properties such as an extremely high quality factor of more than 10,000. Faraday rotation spectroscopy (FRS) exploits the magnetic circular birefringence (MCB) observed in the vicinity of Zeeman split absorption lines. A wireless sensor network over Princeton (SNOP) is deployed over the Princeton University campus and the data collected from SNOP can be visualized and downloaded in quasi-real time.