I have finally made my experimental UAS today. Sorry for the poor quality of photos - made with the iPhone, was too lazy to pick up a descent camera with proper processing.
For light source I used the Surexi F1 LEd modules with optimal for photosynthesis spectra, purchased at the TheLedStore. Initially I planned using these for a first generation ATS, but never managed to actually finish building one. Since this new design was much simpler to make, I decided to give this a go - although I believe that the old design might be more efficient (since at least, there is no light loss on the thick glass and the algae that will grow on it). Anyway, if I don't like this design, I can always take out the screen convert it to the old style scrubber.
Here are the Surexi modules, the match box is for size:
The F1 spectrum module contains 12 red LEDs (with 660nm peak) and 4 royals blues (450nm). Each module is good for up to 5W power, made in wet-proof case (IP66) and has an integrated 60 degrees lens.
I cut 4 50cm long and 6cm wide aluminum sections to serve as the construction base and a heatsink for the LEDs.
I attached the sections to each other with rivets, then drilled holes and tapped threads to attach the LEDs (using a thermal compound, of course).
I attached a low-cost chinese driver on the back. It is capable of up to 90V output at 300mA. All the LED modules were connected in series, with 10V voltage drop on each. This present setup yields 24W of power, if I replace the driver I can safely get up to 40W power from the same LEDs, but I believe there is sufficient light already, to start with.
I processed the canvas like a cactus using the saw, as SantaMonicsa suggests in FAQ. I attached an airstone on the bottom using plastic ties, and then I hung the screen on a plastic rod.