It's probably heavy for vibration damping, since vibration will blur the
diffraction signal.

-----
Regards,
Carl Ijames

"Jon Elson" wrote in message
...
Joseph Gwinn wrote:
In article ,
Jon Elson wrote:

Joseph Gwinn wrote:
FYI. I came upon two interesting goniometer designs.

For the record, a goniometer is a kind of stage that rotates about a
center well outside of the goniometer body, and is used for such things
as rotating crystals whose x-ray diffraction patterns are being
measured, or for rotating an optical lens about its physical center (or
perhaps about one of its optical nodes) in pitch and yaw.


I have an Xray crystallograpy goniometer, if you are interested. It
does have a
hub. It has two concentric spindles, with anti-backlash gears and worm
drive.

Thanks. I don't actually need a goniometer, I was just interested in the
two mechanisms.
OK, I was thinking that it might make a good dividing head, but the gears
are rather flimsy. One thing I can't figure out is why it is so heavy.
It seems to weigh about 100 Lbs, fits in a 1 foot cube, and the gears are
open air and about 1/8" thick. I've been wondering if it has a huge block
of tungsten in the middle, or something, for X-ray shielding.

Jon