Re: [CAD_CAM_EDM_DRO] autocollimators (was Test Peice for 3D finishing)

Hi,

We used a "Photoelectric Autocollimator" on the nuclear submarine I was
on. It shot a beam of light down the center of the missile compartment,
where it entered a "horizontal moving trolley" (made by Otis Elevator
co), was reflected into a little window in the missile tube and into the
missile, where it was reflected from a mirror on the guidance stable
platform, back out the window and back via the trolley again to a
phototube sensor next to the autocollimated light source. All that to
measure "missile misalignment" in the tube. The "trolley" weighed
several hundred pounds, and could seriously injure someone if it ran
into them on it's way to peek into a missile tube.

Alan

Anne Ogborn wrote:

>
> Stuff about autocollimation, including info about using a polygon on
> a rotary table.
>
> http://www.primenet.com/~davoptro/poa.htm
>
> basicly, you shoot a light out through a telescope, bounce it off a mirror,
> and it comes back. If you carefully adjust the mirror, it ends up in
> the same place it started from.
>
> Now if you turn the mirror even a tiny amount, the return beam moves.
>
> The process is incredibly sensitive. As part of my physics education we
> had a class where we had to measure a number of different things, all to
> various insane accuracies. One of the things we ended up with was the
> speed of light.
> Our set up consisted of a laser fired down a hallway. 80' or so away
> was a mirror at a slight angle. The return beam hit a second mirror
> parallel to the first, and so "walked" back and forth 4 times, then off
> into a telescope.
> The thing was insanely sensitive to vibration. We had to do the experiment
> at 3am on a weekend to get the building "quiet" enough to not vibrate.
> Then we had to sit quietly for a long time before we could take measurements.
> The beam went crazy once when a truck drove by outside.
>
> an ad for a commercial autocollimator
>
> http://www.primenet.com/~davoptro/catD-638.htm
>
> And, for what it's worth, last time I was in a laser shop they were
> using a milling machine as an optical table.
>