kouzdra (kouzdra) wrote,
kouzdra
kouzdra

Не курите ведя конфиденциальные разговоры на свежем воздухе

https://en.wikipedia.org/wiki/Laser_microphone
On 25 August 2009, U.S. Patent 7,580,533 was issued for a device that uses a laser beam and smoke or vapor to detect sound vibrations in free air ("Particulate Flow Detection Microphone based on a laser-photocell pair with a moving stream of smoke or vapor in the laser beam's path"). Sound pressure waves cause disturbances in the smoke that in turn cause variations in the amount of laser light reaching the photo detector. A prototype of the device was demonstrated at the 127th Audio Engineering Society convention in New York City from 9 through 12 October 2009.
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