ANALYSIS AND CALCULATION OF RESONANT RESPONSE OF CAVITIES TO USE IN PHOTO ACOUSTIC PHENOMENA

The behaviour of certain resonant acoustic cavities is analyzed. The relative amplitude of the pressure wave on the lateral surface is calculated for a cylindrical cavity of elliptical cross-section. The amplitude of the coherent noise signal resulting from the absorption of the windows that close the cavity is also considered. The amplitude of pressure where the microphone is placed, for spherical and semi-spherical cavities without windows, excited by a led located in the centre, is also calculated. The results are compared with those obtained for a typical cylindrical cavity of circular section with the laser beam centred in its axis. Keywords: photo acoustics, coherent noise, quality factor