A concept of a new microphone which transforms vibrations of a diaphragm to electric signal via a light beam is presented. A light beam coming from a semiconductor laser is focused on the membrane and after reflection it is directed to a photodetector. The photodetector consists of two pairs of photoelements. If the diaphragm does not vibrate the photoelements are lightened uniformly. If the diaphragm is deflected one pair of photoelements is lightened more than the other one and the difference in lighting is proportional to the membrane deflection. A model of such microphone was constructed with the use of an optical system from a CD player.
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