Pro video blog…Produced by Philip Johnston DoP/Editor


General Description

sen-optical-mic1Operating Principle
In the optical microphone, light from an LED is directed onto a reflective diaphragm via an optical-fibre cable (transmitter optical waveguide). The membrane reflects part of the light into a receiver optical waveguide. If the diaphragm is moved by sound signals, a displacement of the reflected light beam occurs, with the result that more or less light is coupled into the receiver waveguide. At the end of the receiver waveguide, a photodiode converts the light intensity variations into electric signals. 

The optical principle is the only microphone principle in which the microphone head and the electronics can be located far away from each other. 

The component parts of the MO 2000 H acoustic-optical microphone head (external diameter ½”) are made of a plastic material that is suitable for use in areas with aggressive substances (gases, salts, humidity) and radiation. All components of the microphone head, including the optical waveguides, are free of metal; no electric current flows. 

These advantages make it possible to use the optical microphone in areas in which other microphones are not suitable.
For example, the optical microphone can be used in potentially explosive atmospheres, such as for the acoustic monitoring of gas drying plants in natural gas production (IAS MO 2000 SET). In this case, the microphone can “hear” slow leaks, which, due to their small size, cause neither a pressure loss nor an alarm message in the other monitoring systems. 

In medical applications, the microphone is ideal for use in magnetic resonance imaging (MRI), for example to maintain communication with the patient during MRI scans or to achieve active noise cancellation in MRI. The optical microphone does not disturb the imaging process and is itself not influenced by the strong fields inside magnetic resonance imaging equipment.

In measuring technology, the microphone is ideal for use in EMI/EMC laboratories, as it does not influence the electric field. In this case, for example, it functions like an “ear on a mobile phone”. 
A further application possibility is in the field of undetectable acoustic monitoring.

Delivery Includes
  • 1 optical microphone with MO 2000 H optical cable (3 m)
  • 1 MO 2000 CU central unit
  • 1 power supply with various adapters (EU, UK, US)
  • 1 carrying case
  • 1 operating instructions

Having been working in the video business since 1988 I have amassed a great amount of knowledge of both the kit and production values over the last 30 years.

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