Why is the sky purple in the reflection of my friend's glasses?
Why is the sky purple in the reflection of my friend's glasses?
They're just regular (prescription) glasses. The sky looks normal through them. What's the deal?
Most likely uv protective coating.
Any coating might produce this through reflective destructive interference.
True but where I live in CA this would likely be the coating selected by the majority of people.
The anti-reflective (AR) coating can create blue or purple reflections from certain angles. The coating is meant to block some of the UV spectrum of light to help protect your peepers. It also prevents some of the reflections that would be annoying, hence the name.
Some coating on the glass is very faintly purple. Could be UV protection, anti glare, anti fog, etc.
Glass itself is very faintly green, so it’s not the color of the glass, unless they are made out of some other material (something like polycarbonate or sapphire).
Just to be pedantic, it's not that the coating, itself, has any color; it's usually clear, actually. The color shift is caused by the glass and the coating having different refractive indexes, causing the light to split up slightly as it reflects off the lens. Kinda like an oil slick on the street reflecting bright greens and purples that aren't actually there.
I mean, can you really say that something doesn't have a colour if you see it as that colour? Does it really matter that the colour is coming from different refractive indexes rather than that wavelength not being absorbed by the material? If it consistently happens in that set of circumstances, isn't it fair to say that is its colour? I.e. the coating, oil slicks
blue light filtering
It is because they have blue light filters on the glasses. It's common now days.
This is because your friend is a wizard, and their personal objects pick up a magical blue-purple hue the more they are handled. This is a gradual process, so it's not noticeable on most of their things, but they wear their glasses every day so they pick up the hue at a steady rate.
Lol thank you! So helpful ;)
Thank you, that is very interesting. They said they remembered being told at some point that there was a coating on the glasses.
It's standard to have UV protection.