Fiber optic mics

[reich_fan]

Hi,

I was just wondering if anyone knows if there has ever been an attempt at creating a microphone which uses interferometry. Interferometers can be used to measure dynamic pressure from 10Hz-100kHz. Usually a reflective diaphram is used in order to induce a phase shift into the light signal proportional to the displacement of the diaphram.

 

[ausrock]

I have seen some references to a "diaphram-less" (in the conventional sense) mic, which from memory uses light, as being under development.............no specific details were given at the time though.

I guess we will just have to wait and see.

 

[mgraffeo]

well, over at Recording.org, I've seen Stephen Paul talk about a "Laser mic" that he's working on, for some time down the road. It's certainly possible that it's based on the same idea.

I've also tossed around the idea with a colleague of mine, and feel pretty confident that it would work. The trouble is in the design & execution, not the theory. The diaphragm of a mic, since it's under EXTREMELY high tension, really doesn't move much at all, even at high SPL. So, you need to be able to detect very, very small shifts, and amplify that considerably.

-mg