[time-nuts] position determination over short distance

[Tom Van Baak]

> I need to determine the position of a instrument with a 1mm accuracy or less.
> The instrument is not connected to a mechanical device but is separate &
> independent.
> The surface which the instrument is positioned on is close to the size of a
> 11"x11" square.

1 mm or better accuracy on a 300x300 mm surface can be
obtained with a cheap webcam mounted above the surface
and a little bit a creative software.

> Obviously this is used to triangulate the position of the instrument.
> Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
> would have to have that or better resolution.

Sound travels about a million times slower than light. 343 m/s
is 1 mm in 2.9 microseconds. Perhaps this is the way to go?

I remind visitors here that a WWV tick takes the same time to
travel from Ft Collins to Seattle as it does to travel from the SW
radio speaker to your ear.

/tvb