In article ,
Winston wrote:

Bob AZ wrote:

(...)
http://www.metalworking.com/dropbox/...fying_lens.txt
http://www.metalworking.com/dropbox/01april09_002.jpg

Got it!

I have no idea what that is.

I'd venture a guess that it's a beam expander, used with a matching
positive lens assembly to take a laser bean (~1 mm diameter) and expand
it to fill the aperture of an optical system (~10 mm diameter).

The positive and negative lens assemblies will be identical, differing
only in the kind of lens that's mounted. The lens powers will be
identical, except for sign.

The metal post and parallel fin look like they are designed to allow
vertical adjustment while preventing rotation. This is convenient on an
optical bench.

A posting to sci.optics will probably evoke the make and model, if my
guess is correct.

Joe Gwinn