Subject: Re: [linux-audio-dev] off topic, optical protocols
From: Nick Bailey (n.j.bailey_AT_elec.gla.ac.uk)
Date: Tue Mar 05 2002 - 19:13:43 EET
Nope, I meant a Michaelson interferrometer. This has a single
detector is used and it counts interference fringes as the
distance between the diaphragm and laser changes. So you are
actually measuring displacement to the accuracy of a
wavelength of light, and using a counting process (which is
truly digital in my book). I suppose you have to make the
diaphragm only vibrate in its lowest mode. You also need a
coherent light source (LEDs won't do 8-)
But since I can't find any references to this (I've just
looked again), it is probably a joke I didn't get. Let's
patent it anyway 8-) The technology needed is described here
(but not in a high quality application):
http://www.williamson-labs.com/laser-mic.htm
Nick/
On Tuesday 05 Mar 2002 3:06 pm, you wrote:
> What you are making in itself is an analog to digital
> converter. Questions that pop off the top of my head:
>
> 1. different angles will have different lengths to the
> detectors, are you thinking of making the detectors curve
> to the geometric shape?
>
> 2. Since the laser will not be a point but a spreading of
> light, how will that affect the spreading at different
> angles on a curves surface, will you hit too many bits at
> once?
>
> 3. The mass of the object and its center point holding
> method will probably provide some distortion due to
> momentum change and spring like affects.
>
> 4. As I can see it, each optical detector is a level
> indicator. To get the same resolution as a 16-bit A/D you
> would need 65000 detectors, is that feasible?
>
> Rick
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