Laser Microphones

MarcoPogo · Post by **MarcoPogo** » Wed Sep 30, 2009 9:48 am

***So, here are the beginnings of an interesting type of microphone technology:

http://www.smartplanet.com/business/blo ... ence/1091/

Microphones with no diaphragm, no mass, no resonance. Obviously it's very early days, especially judging by the sound examples. Funny how demos of audio technology often have bad audio... The "Mary Had A Little Lamb" recording refers to Edison's very first gramophone recording.

Still, cool stuff. One imagines that in time we could have very high quality and potentially inexpensive mics using this technology.

-MR

Mark Rubel
Pogo Studio
Champaign, IL USA

calaverasgrandes · Post by **calaverasgrandes** » Wed Sep 30, 2009 1:26 pm

I am just a half-ass of an engineer, but it kind of bothers me that they used smoke. There are wavelengths that would be more deflected just by the air itself. IIRC the higher in frequency you go there is more interference from the air. Using smoke is just not practical in a real mic. Also smoke particles do have mass and also will leave residue.
Cool idea though.

roygbiv · Post by **roygbiv** » Wed Sep 30, 2009 2:22 pm

I can already imagine the for-sale ads on TOMB Buy/Sell: "mic was used only in a smoke filled studio"

The Scum · Post by **The Scum** » Wed Sep 30, 2009 9:47 pm

Hasn't the CIA been bouncing lasers off windows for ages, to hear the conversation on the other side?

And there was a pretty interesting article by Steve St Croix a while back about a laser mic he'd devised for drumset...like a little reflective patch on the drumhead that vibrated, modulating the laser. He spent a whole article building the thing up...and then promptly tore it back down, because the sounds from them were horrible.

klangtone · Post by **klangtone** » Wed Sep 30, 2009 10:18 pm

not a laser mic, but sort of on the subject of new kinds of mics, are you guys familiar with MEMS mics? They're only finding use in cell phones and similar things like that, but they're not too shaby and impressively manufactured directly in silicon. Hence they're super small and ideal for making microphone arrays with. One day maybe we'll see a studio quality mic using MEMS. Who knows...

There are a lot of manufacturers now. Analog Devices might be one of the better ones:

http://www.analog.com/en/audiovideo-pro ... index.html

The sample in the video is only speech since the audience is probably cell phone makers. But it sounds pretty similar to the fancy B&K reference mic.

Roy

calaverasgrandes · Post by **calaverasgrandes** » Wed Sep 30, 2009 10:20 pm

Moment of silence for Stephen st.Croix.

ubertar · Post by **ubertar** » Thu Oct 01, 2009 5:52 am

klangtone wrote:not a laser mic, but sort of on the subject of new kinds of mics, are you guys familiar with MEMS mics? They're only finding use in cell phones and similar things like that, but they're not too shaby and impressively manufactured directly in silicon. Hence they're super small and ideal for making microphone arrays with. One day maybe we'll see a studio quality mic using MEMS. Who knows...

There are a lot of manufacturers now. Analog Devices might be one of the better ones:

http://www.analog.com/en/audiovideo-pro ... index.html

The sample in the video is only speech since the audience is probably cell phone makers. But it sounds pretty similar to the fancy B&K reference mic.

Roy

What's the principle behind how they work?

The Scum · Post by **The Scum** » Thu Oct 01, 2009 11:02 am

From this pic:

It would appear that they're condenser mics, with the diaphragm and backplate etched into the semiconductor substrate.

And packaged in such a way that you'd need SMT zen to make use of them...though the 3.3V, 250 uA power supply shouldn't take much to cobble from a phantom supply.

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