[LAU] Optical microphone sees sound like never before

[Fons Adriaensen]

On Wed, Jun 22, 2022 at 10:57:10PM +0200, David Kastrup wrote:
 
> I was of the opinion that laser-based interferometry microphoning off
> window panes had already been standard fare of secret services for
> decades.

Indeed this not new, and there are many variations of such methods.
Some don't even use a laser, just a high speed camera.

To be precise, none of them actually pick up sound. They capture
vibrations which are either caused by sound (as for eavesdropping),
or which cause sound (when recording an instrument such as a guitar).

Even the method used in this case to measure the interference is not
really new, it has been used mutatis mutandis in other applications.

-- 
FA