J. Phys. IV France 125 (2005) 677-679
Improved pulsed photoacoustic detection by means of an adapted filterM. González1, G. Santiago1, A. Peuriot2, V. Slezak2 and C. Mosquera1
1 Laboratorio Láser, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850 (1063), Buenos Aires, Argentina
2 Centro de Investigaciones en Láseres y Aplicaciones (CITEFA-CONICET), Juan Bautista de La Salle 4397(1603), Villa Martelli, Buenos Aires, Argentina
We present a numerical and experimental study of two adapted filters devised to the quantitative analysis of weak photoacoustic signals. The first one is a simple convolution-type one and the other is based on neural networks of the multilayer perceptron type. The theoretical signal used as one of the inputs in both filters is derived from the solution of the transient response of the acoustic cell modeled with a simple transmission-line analogue. The filters were tested numerically by using the theoretical signal corrupted with white noise. After 500 iterations it was possible to define an average error for the returned value of each filter. Since the neural network outperformed the convolution-type, we assessed its performance by measuring SF6 traces diluted in N2 and excited by tuned TEA CO2 laser. The results show the use of the neural network filter allows recovering a signal with poor signal-to-noise ratio without resorting to extensive averaging, thus reducing the acquisition time while improving the precision of the measurement.
© EDP Sciences 2005