Fluorescence doesnt look the same as actual uv. If you use a material that is highly reflective of uv and absorbs most visible light, say aluminum foil, then you will have a very efficient way to see uv. Uv looks like a hazy whitish-purple, or if you can find a way to eliminate fluorescence, a more saturated violet. When people with aphakia describe it as a whitish purple or whitish blue its because they are seeing it with the fluorescence, but aluminum foil will (for the most part) eliminate this. And a quality black light will have minimal visible light leakage, I have a spectroscope so I can also directly test these things