For instance, I’ve enjoyed shooting the beam through tonic water and seeing the fluorescence from quinine. Here’s some total internal reflection:
Any other ideas for cool “experiments”?
(Note, please be careful with this or any laser pointer. Although the purple light emanating from this pointer doesn’t look bright, it can damage your eye or skin. Even if your eyes aren’t sensitive to 405 nm, that doesn’t mean they can’t be damaged by 405 nm. This pointer is dangerous to be viewed even in diffuse reflections.)
(P.S. The sorta shitty photo credited to E.Y.L.)
UPDATE: It turns out that urine is also fluorescent:
Especially after taking a multivitamin.