I did something similar last year, but I was more focused on spectrum and used high powered movie lights, since their spectrum output is much better and you get a lot of lux. You can get most of the parallel light ray effect by adding a hyperrefelector which conveniently comes with most lights. I then added an incandescent heat lamp to fill in the IR part of the spectrum and some dedicated UV LED lights for the UVA part. I'm not brave enough to put in a UVB specific lamp.

I wrote about it here: https://metrep.substack.com/p/improve-your-focus-productivit...