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Idea for a microphone.

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poor mystic

Junior Member level 2
Jul 19, 2010
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New South Wales, Australia.
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Hi People! :)
I've had an idea for a monochrome light microphone, which I have rendered as a drawing, attached.
The detector consists of a monochrome source (l.e.d.), a reflective membrane (gold leaf) some distance from the source, a static reflective element, and several randomly-placed detectors, 3 of which are shown.
The idea is that as the membrane moves towards or away from the plane of the source and detectors, each detector will be excited at different times, when constructive interference exists between the light reflected from the moving membrane and the light reflected from the static reflectors.
As a sound wave pushes the membrane towards the detectors, the detectors will tend to be excited in some charcteristic repeating sequence, I hope; the order will be reversed when the membrane is moving away from the detectors.
With 'towards' and 'away' discrimination provided by the sequence discriminator, a count can be incremented or decremented respectively. The state of the count therefore shows to a fine precision the position of the gold leaf.
Questions & Problems
First, I wonder whether this has been tried before, and then I'm looking for any ideas on how to train some kind of sequence discriminator to recognise "toward" and "away" movements of the membrane so that the count can be added to and subtracted from accordingly.
As for the biggest problem I think I'd be a lot better off using a low infrared monochrome source than a visible light source. This is because there are so horrendously many wavelengths of visible light per millimeter. It would be better to use a wavelength of hundreds of nanometers.

Still, it's just an idea at this stage... any thoughts?


  • light microphone.png
    light microphone.png
    221.5 KB · Views: 111
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Thanks KAK
those microphones seem to work on a different principle... although they are "light microphones" I don't think they are "interference detector light microphones".
Does anyone know of any low-frequency i.r. monochrome sources and detectors? It would want to be a wavelength of at least 80-100 micrometers.

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