Need suggestion on UV source making su-8 master, better to be LED.

Guys. I'm having difficulty getting ultra-fine feature of su-8 master using
our UV-aligner. We have been making features ~40 microns with no problem.
But when I push the limit to ~10 microns, it is very difficult with our
home-made aligner, often resulting either cracking or un-crispy structures.
The UV source is especially lousy. The intensity is neither uniform nor
well-focused, and generates too much heat. Can anyone recommend a good UV
source? I was hoping any LED lamp can be used. Our layer is thin, so won’t
need too much energy output.

Thanks a lot!

--
Yu Huang
Materials Science Program
NITRO, Biomedical Enigineering Department
University of Wisconsin-Madison
Cell Phone (608)-334-3689