Signal-to-Noise Analysis of the Improved Open Photoacoustic Helmholtz Cell

Abstract

Open photoacoustic cells are often used in continuous-flow photoacoustic measurements. Such cells are sensitive to external noise penetration. The improved open photoacoustic Helmholtz cell has much better external noise attenuation than the previously known designs. This paper describes how mechanical dimensions of such a cell influence its signal-to-noise ratio. The analysis was performed by means of computer simulations based on the loss-improved transmission line model. This research showed that the mechanical parameters affect signal-to-noise noticeably and, if they are properly chosen and applied in the design of the improved open cell, the resulting signal-to-noise ratio may be improved by almost 60 dB in comparison to previous designs of open photoacoustic Helmholtz cells.

Signal-to-Noise Analysis of the Differential Open Photoacoustic Helmholtz Cell

“…It was discovered that, as in the previous analyses of Helmholtz cells [29,34,35], the best result is obtained for an intermediate value. According to the simulations, in the case of the internal ducts, the signal-to-noise ratio is best at a length of 100 mm, while in the case of the external duct, the signal-to-noise ratio is best at a length of 125 mm (Fig.…”