In Blender 2.92 Cycles, I'm trying to model a quartz prism with physically correct refraction of a beam of light cast by a narrow slit (not worried about the color dispersion yet). But when I render it, the beam of light doesn't bend, and it doesn't seem to exit the prism in any meaningful way at all. According to my calculations, it should go horizontal inside of the prism, and exit at a symmetric angle to how it entered.
I'm using a plain ol' glass material for the prism with an index of refraction of 1.6, although I get the same results using the principled shader. Any ideas why this doesn't work?
Edit: Also, if I change the prism to 100% glossy metal, it doesn't cast a sharp reflection caustic of the beam either. I'd expect to see a discrete blue reflected beam on the floor here, instead of the soft glowy caustic I actually got. Maybe Cycles can't actually do these kinds of things... or is there a "use actual optics" setting I can turn on?