Gas detection is assuming a crucial role in many real world applications, such as environmental monitoring, industrial process control, petrochemical industry, safety and security, and biomedicine. Among optical techniques, Quartz Enhanced Photoacoustic Spectroscopy (QEPAS) has been demonstrated to be a leading edge technology for addressing the above application requirements, providing also modularity, ruggedness, portability and allowing the use of extremely small volumes.
In QEPAS, QTFs are also widely used as a sharply resonant acoustic transducer to detect weak photoacoustic excitation. QEPAS technique does not require an optical detector, it is wavelength independent, it is immune to environmental noise and can operate in a wide range of temperature and pressure.
QTFs have also recently demonstrated their capability to operate as sensitive and broadband infrared photodetectors for absorption spectroscopy. To maximize the photoinduced signal, the laser beam has to be focused on the quartz surface where the maximum strain field occurs, typically nearby the QTF prong based and under these conditions the LITES signal to noise ratio is proportional to the product of the strain and the QTF accumulation time. This technique combined with the tunable diode laser absorption spectroscopy approach, known as light induced thermoelastic spectroscopy (LITES) has been explored in the last few years.
Starting from the main principles governing the Quartz tuning fork (QTF) physics, Spagnalo will review the latest results achieved by exploiting custom QTFs focusing on real world applications.
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Target audience
Researchers, scientists, teachers and students of physics
Further information
Associate Professor Robert Fickler, robert.fickler@tuni.fi