UV Spot Light (365nm)

Producing inexpensive, bright, collimated light at 365nm is a non-trivial problem and there are no commercial units available that could be had at a reasonable price.  However, this is exactly what is needed for doing good lithography at home.  This is one of those times where "Buy-Don't-Build" simply wasn't true, and I had to figure out another way through.

The result wasn't pretty, but it got the job done.  It made use of 10 high powered 365nm LEDs thermally mated to a piece of aluminum.  These were driven with an adjustable constant current power supply.  On the rear of the aluminum was two large Peltier cooler heat sink assembly driven with a separate 12V power supply.

LEDs throw most of their light forward.  The traditional method for collimation is to use parabolic reflectors, however, these won't catch most of the power.  Instead, I found UV transparent fresnel lenses that closely match the throw (NA) of the LEDs.

Each lens of the lens assembly can be individually shifted to point the individual LED light to form a user-defined pattern.  The entire lens assembly adjusts in and out on three spring-loaded rods with thumb screws to obtain the right amount of focus.  The resulting spot was about 3ft across at 30ft distance.