From: Robkin, Eugene (erobkin@uwc.edu)
Date: 04/17/03-09:50:30 AM Z
Dear List
Last week I bought from one of my local surplus sources a 200 watt OSRAM
Super High Pressure mercury arc lamp. These lamps have a quartz
enclosure and give out a lot of short wavelength UV. One of their main
applications is in photolithography for the semiconductor industry. The
arc is around 1/4 inch long so it is an approximation to a point source.
It seems to me that an optical system for an enlarger based on this
could use pinholes and mirrors rather than lenses and possibly bypass
focusing issues.
It appears to be brand new but I have no idea how old it is. It came
with some of its original literature (in several languages) which should
allow someone competent to get a good idea of how to build the ballasts
and arc igniters it needs. There is quite a bit of information on the
OSRAM web site but I did not find a specific listing for anything I
identified as an exact match although there are lamps the come very
close. I also don't know how much help would be forthcoming from OSRAM.
I would not be surprised if all the necessary design data is a trivial
extension of what they already do for lithography. Perhaps their
interest could be aroused for some donations.
I'll consider giving the lamp to anyone on the list who can come up with
serious ideas for plans for an enlarger using a lamp like this and who
is willing to share complete details of what they do with the rest of
the list. This is not as generous as it may appear. It cost me nearly
nothing and its resale value is not all that high. Similar new lamps
from OSRAM cost in the $120 - $250 range but commercial ballasts cost a
lot more and design/construction time is a real issue. This particular
lamp can only be used in the vertical position so the enlarger will have
to be horizontal or some kind of mirror system will be needed. Actually
a focusing mirror may be a big help.
An ideal response would be a design for ballasts and the rest which
would allow others on the list to build an enlarger with minimal costs.
Maybe not more than two or three times the commercial lamp costs as a
target.
One thing to keep in mind is that these lamps can explode in use with
considerable force. Usually short of deadly but capable of taking a big
piece of your face off not to mention having extremely hot quartz bits
embedded in you. If you are interested, include something about how you
are going to handle the safety issue. Basically you need an explosion
proof lamp housing. You will also need to plan on how to vent the small
amount hot mercury vapor released if the lamp pops. I am concerned that
these safety issues may be too high a hurdle for do-it-yourself
design/construction using high pressure lamps.
Please contact me off list if you are interested. If more than one,
I'll find some help to sort out the choice. I can send copies of the
literature (tell me what language) if you want to look at that first.
I'll see about getting the paperwork scanned so I can email what you
want. I recommend some exploration of the OSRAM web site as a
preliminary.
I hope there is some use in all this.
Gene Robkin
erobkin@uwc.edu
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