Photoacoustic effect

The photoacoustic effect ( PAE), also called optoacoustic effect is a physical effect that makes the optoacoustics advantage. He describes the conversion of light energy into acoustic energy (sound ). Was first described in the photoacoustic effect in 1880 by Alexander Graham Bell. Shortly thereafter also published other well-known scientists such as Rayleigh, Wilhelm Conrad Röntgen, and John Tyndall work to this effect.

Description

Is a propagation medium irradiated with light, a portion of the light energy is absorbed by the medium ( absorbed) and converted into heat energy. The thermal conductivity of the energy is distributed after a finite time in the medium and it turns a minimally elevated temperature in the media ( heat loss by radiation, etc., are not considered for simplicity ). Due to the heat it comes inter alia, to increase in volume or to decrease in density.

The medium is irradiated with a sequence of flashes of light, results in a periodic heating and " cooling ". This constant change of volume expansion and reduction represents a sound source Represents the body may be sound in the solid state or normal sound in the gas.

Application

The photoacoustic effect is used in the case of photoacoustic spectroscopy and photoacoustic tomography for investigation of gases, solids and tissues.