On Wednesday, 24 October 2012 08:57:21 UTC+1, Roel Baardman wrote:
My money would be on a Particle Image Velocimetry (PIV) based
solution.

Largely because this is technology which is extremely widely used
(every laser mouse does it in hardware).

Optical mice use integrated circuits like the Agilent ADNS-2620:
http://www.datasheetcatalog.org/data...cyqglz0hcy.pdf

So, unless you can form a 2D image of the particles'
velocity and have the ic process that image, I don't
see how you would do it.

I've heard about model airplanes using it to stabilize bank angle
(more speed = lower wing).

Quite possible. Many years ago I saw one of the
optical mice in the form or a ring on a finger.
With the appropriate focussing distance, the room
itself was used as a mouse pad.