What happens if a light source would slowly decrease the wavelength from visible to nonvisible light?

Question

Ie if we had a light that could emit light from purple to UV. Do we see an instant change from purple to nothing or does it slowly fade out?

In: Physics

Answer 1

I’ve seen this at the near-IR end of the scale a lot, because I used to deal with really high powered near-IR lasers. You can absolutely see near IR if it’s bright enough, even up to like 780 or 800nm. The problem is if it’s bright enough for you to see it, it’s dangerous. It’s always a “fuck I forgot my goggles” moment if it happens. (it just looks red, naturally)