Acoustical Society of America
ASA/EAA/DAGA '99 Meeting Lay
Language Papers

A Simple Optical Microphone

Wolfgang Niehoff -
Sennheiser Electronic GmbH & Co KG
Am Labor 1, D-30900 Wedemark,Germany
Tel. +49 5130 600 442, Fax +49 5130 600 330

Popular version of paper 2pEA2
Presented Tuesday afternoon, March 16, 1999
ASA/EAA/DAGA '99 Meeting, Berlin, Germany

In the past, there were quite a few suggestions for the construction of optical microphones. The latest innovation is an optical microphone working on the principle of intensity modulation.

Modulation Principle

The optical microphone transfers the oscillation of its diaphragm to a beam of light, a process that does not involve any electrical signal. It is only later in the conversion process that a photodetector transforms the light into an electrical current. One of the special advantages of this novel type of microphone is that the actual microphone head and the photodetector (plus the light source) can be placed several hundred meters apart - thanks to low-loss transmission via glass fibres. This makes the optical microphone an ideal choice for use in strong magnetic fields or in locations which are difficult to reach.

SENNHEISER has developed the optical microphone in cooperation with Israeli company PHONE-OR