The photoacoustic effect is the formation of sound waves after absorption of the irradiated material. It allows to transmit speech and music over a distance.
The photoacoustic effect is the formation of sound waves after absorption of the irradiated material. For the occurrence of the photoacoustic effect of the light intensity should vary periodically or defined by pulses of radiation.
As a rule, for the formation of the photoacoustic effect using light in the visible, ultraviolet and infrared range.
The mechanism of the photoacoustic effect is that irradiation with light, the irradiated material is heated in place of the absorption of light. If you change the light emission material that is heated, then cools. Irradiation of light causes not only local heating of a material in place of the absorption of light (workspace), but also local increase in pressure and density of the material. As a result of periodic changes of light you experience intermittent fluctuations – thermal and acoustic waves, which propagate throughout the material. This so-called classical photoacoustic mechanism or the classical method of transmitting sound to a distance by means of light radiation.
In addition, the photoacoustic effect can be caused by the movement of the light spot on the stage at supersonic speed. Due to this, in the work area formed a coherent sound wave, the interaction between which leads to increased sound. The photoacoustic mechanism received the name of the method with a sliding beam.
The photoacoustic effect is mainly used for non-destructive spectroscopic analysis of the composition of materials.
But experiments conducted by scientists have shown that both the mechanism (method) of the photoacoustic effect make it possible to transmit speech and music at a distance with a volume similar to the volume of the background conversations. Scientists have managed to create a sound with a loudness of 60 dB at a distance of 2.5 meters from the source of light.
Here are the links to the sources:
https://www.osapublishing.org/ol/abstract.cfm?uri=ol-44-3-622 ; https://nplus1.ru/news/2019/01/29/photoacoustic ; https://youtu.be/UYr3zPP5rCw .
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