Title: Converting sunlight into audible sound by means of the photoacoustic effect: The Heliophone
Authors: Roozen, Bert # ×
Glorieux, Christ
Liwang, Liu #
Rychtarikova, Monika
Van der Donck, Tom #
Aernoudt, Jacobs #
Issue Date: 5-Sep-2016
Publisher: American Institute of Physics for the Acoustical Society of America
Series Title: Journal of the Acoustical Society of America vol:140 issue:3 pages:1697-1706
Abstract: One hundred and thirty-five years after Alexander Graham Bell and his assistant Charles Sumner Tainter explored the photoacoustic effect, and about 40 years after Rosencwaig and Gersho modeled the effect in a photoacoustic cell configuration, we revisit the phenomenon, in a "heliophone" device that converts sunlight into sound. The light is focused on a carbon blackened copper coated Kapton
foil in an acoustic cell by means of a compound parabolic collimator, and its intensity is modulated by a mechanical chopper. A horn is employed to make the sound audible without electronic amplification. The description of the photoacoustic effect that was introduced by Rosencwaig and Gersho is extended to a cell-horn configuration, in which the periodically heated air above the foil acts as an oscillating piston, driving acoustic waves in the horn.
The pressure in the cavity-horn assembly is calculated by considering the air layer piston as an equivalent volume velocity source. The importance of the carbon black (soot) layer to enhance light absorption, but above all to enhance the photothermal excitation efficiency, is elucidated by means of an experimentally supported physical model.
ISSN: 0001-4966
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Department of Materials Engineering - miscellaneous
Soft Matter and Biophysics
× corresponding author
# (joint) last author

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