How a microphone operates is a quite simple principle to understand. The emission of a sound causes the air movement that is captured by the flexible membrane of the microphone. The membrane translates this acoustic signal into an electric signal which is transmitted to the amplification system. This latter system does the reverse operation i.e. converting the electric signal into an acoustic signal. And then you’re set to bother the neighborhood with your all night long screams and shouts…
So far there is no better system or device to capture the sound of anything that produces noises. At least until David Schwartz (Institute of Technology in Rochester) have not pursued his research and developed his futuristic and innovative microphone. He imagined to replace the flexible membrane by synthetic smoke and a laser beam. The principle is once again relatively simple to understand. A laser beam passes through a stream of particles created by a synthetic smoke generator. The smoke modulation caused by the air pressure variation is detected by the laser beam, and these variations are translated into an electric signal by a photoelectric cell. And voilà!
Well, the voilà part might be a shortcut because I guess it is not that easy to develop such a device. But once developed it should be the very first and only real high fidelity microphone. Why should it be? The capture of the acoustic signal will no longer depend on a mechanical part: the membrane which intrinsic properties (flexibility, ageing,…) alter the sound. To be highly speculative, I guess it could even be possible to calibrate the sensor associated with the laser beam to reduce the generated background noise. This would be a great feature that is impossible to integrate in the conventional microphones (though this wouldn’t be so great for the makers of noise reduction devices).
The creator of this prototype is already dreaming on the possibility of creating a real microphone modelizing unit via plug-ins, and this is probably the greatest interest of this innovation. I guess recording studios won’t be ready to give up their priceless collections of microphones (that would be crazy). But the home-studio musicians should be very interested in such a versatile microphone. Though the device is still far from perfect, the principle itself is completely valid.
Here are two videos of the prototype.
Spotted via @Zikinf