Barbara Foster wrote:
>
> Since glass is opaque to UV of 365-380 nm or shorter, any type of glass
> glasses (i. e., hardened safety) would be OK.  Suggest you insert a neutral
> density filter to cut the brightness.
>

I would not rely on glasses which are not rated for a standard (such as
an OSHA standard or similar). Glass which is not supposed to pass UV may
pass 5-10% of the near UV (like mid 300's). Even if it is only 1%, and
bright source can provide enough UV to be damaging, and the damage can
be cumulative.
So if you have even incidental UV illumination (like an arc lamp which
is not 100% enclosed and which can illuminate your peripheral vision),
get real wrap around UV goggles. There are some nice polycarbonate
goggles properly rated which are not very expensive (years ago they were
under $50 -- now I dont know).

In any case, it is possible to align the lamp without projecting it on
the wall, as have been pointed out in many posts.
I will just add that I have a set of acetate colored gel filters which I
bought from Edmund, which are about 8.5x11 inches in area. They are
handy when
aligning the image which appears on the paper which I place on the stage
to
see the arc, which is quite bright. A  properly selected filter (they
come as a set so it is easy to find one that works) allows me to see the
arc at a pleasant illumination level, and they are large so it is easy
to stand at a distance and get a decent field of view, while
manipulating the adjustments on the UV lamp housing. They can also be
cut with a scissors and made to fit into any convenient holder.

--aryeh
--
Aryeh Weiss                          | email: [log in to unmask]
Department of Electronics            | URL:
http://optics.jct.ac.il/~aryeh
Jerusalem College of Technology      | phone: 972-2-6751146
POB 16031                            | FAX:   972-2-6751275
Jerusalem, Israel                    | ham radio: 4X1PB/KA1PB