Homebrew PCBs

Hi Folks,
I'm mostly a learning lurker on these tech exchange lists, but the 
recent UV source discussion has stimulated a question I've been 
wondering about. I need a really compact UV source for a very portable 
exposure unit. Anyone know of any success using an array of UV LEDs 
as a UV light source for exposures? LEDs are pretty directional, so 
are fairly well collimated as is. And in their visible light forms, 
bright enough to use in traffic lights. But can these UV LEDs put out 
enough light energy to react the photoresist? Anybody have experience 
or know?

-Karl in Kalifornia