In article ,
"Bill Noble" wrote:

"Joseph Gwinn" wrote in message
...
In article ,
Wes wrote:

Joseph Gwinn wrote:

As for manufacture by a HSM, either approach is practical, but the Wyler
approach is far simpler mechanically. In either case, the electronics
part is dead simple by present-day standards, but was a big deal back in
the 1960s and 1970s.


Are you planning to try it? Btw, thanks for the list of patents.

I am thinking about making a level. Don't know if I'll really do it.
Probably depends on how practical an approach I can dream up.

snip

If I wanted to make a precision level today - more precise than a
starett/vis master level, then I think I'd do the following

1.erect a perpendicular over the base material - one might use a surface
plate or other optically flat material for the base.

2. drop a penduluum from the perpendicular - longer is better so long as the
perpendicular in fact remains perpendicular

3. place a mirror at the end of the penduluum, and arrange mirrors along the
base to direct beams from a low powered laser. Mirror at base should have
an angled and a straight part

4. use an interferrometer to measure the final centering of the penduluum -
first, just use the laser to roughly center by using the angled mirror to
form an optical amplifier and use a wall, maybe 20 feet away to get the
thing aproximately centered (this should get you to a micro inch or so).
After that, use interferrometry, this will get you to 1/2 wavelenght - so
depending on your choice of emitter, somewhere in the 200 to 500 angstrom
range. With a 1 meter perpendicular, that should give you what .... inverse
sine of 1E-8=?? - well, using small angle aproximation, 1e-8 radians

Is that good enough?

It's about 100 times better than the Wyler and Taylvel units, which are
only good to one microradian, but portability and applicability to lathe
beds and surface plates could be a challenge.

Perhaps a Sagnac interfereometer would be a suitable tiltmeter? There
is a nice one in a deep bomb shelter and command center in New Zealand:

http://www.ringlaser.org.nz/content/c-2.php

http://en.wikipedia.org/wiki/Sagnac_effect


Joe Gwinn