Quartz enhanced photoacoustic spectrophone employing conical acoustic resonator

Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) is a highly sensitive technique for trace gas detection and environmental monitoring, leveraging the piezoelectric properties of a Quartz Tuning Fork (QTF) to convert acoustic signals into electrical signals. Traditional QEPAS configurations often face limitations due to environmental noise interference and stringent requirements on laser beam quality. In this work, we present a novel QEPAS spectrophone design incorporating a conical acoustic resonator positioned perpendicularly to the QTF axis and located on one side of the QTF prongs. The conical resonator features a gradual change in cross-sectional area, enhancing acoustic impedance matching and concentrating acoustic energy at the QTF, thereby amplifying the photoacoustic signal. Finite Element Method (FEM) simulations were conducted to model the acoustic field distribution within the resonator, revealing that the acoustic pressure at the QTF prongs increases with the inner radius of the resonator's second side up to an optimal value. The conical acoustic resonator offers superior performance over traditional cylindrical designs, providing enhanced sensitivity, noise reduction, and greater flexibility in practical applications of QEPAS sensors.