They're just regular (prescription) glasses. The sky looks normal through them. What's the deal?
Most likely uv protective coating.
this post was submitted on 04 Nov 2024
38 points (85.2% liked)
Ask Lemmy
26903 readers
1524 users here now
A Fediverse community for open-ended, thought provoking questions
Please don't post about US Politics. If you need to do this, try [email protected]
Rules: (interactive)
1) Be nice and; have fun
Doxxing, trolling, sealioning, racism, and toxicity are not welcomed in AskLemmy. Remember what your mother said: if you can't say something nice, don't say anything at all. In addition, the site-wide Lemmy.world terms of service also apply here. Please familiarize yourself with them
2) All posts must end with a '?'
This is sort of like Jeopardy. Please phrase all post titles in the form of a proper question ending with ?
3) No spam
Please do not flood the community with nonsense. Actual suspected spammers will be banned on site. No astroturfing.
4) NSFW is okay, within reason
Just remember to tag posts with either a content warning or a [NSFW] tag. Overtly sexual posts are not allowed, please direct them to either [email protected] or [email protected].
NSFW comments should be restricted to posts tagged [NSFW].
5) This is not a support community.
It is not a place for 'how do I?', type questions.
If you have any questions regarding the site itself or would like to report a community, please direct them to Lemmy.world Support or email [email protected]. For other questions check our partnered communities list, or use the search function.
Reminder: The terms of service apply here too.
Partnered Communities:
Logo design credit goes to: tubbadu
founded 1 year ago
MODERATORS
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
Here’s the thing: if you change the thickness of the layer then the colour will change along with it, but the material is otherwise the same. This occurs because the layers produce a phenomenon known as thin film interference. So it’s not the material of the coating layer that produces the colour, it’s the interaction between two layers.
Anyway, you can see all of the colours of a light’s spectrum through a prism but you wouldn’t say the prism itself is any of those colours. It’s transparent and refractive. That’s all we have here with the glasses: refraction and reflection, with interference of certain wavelengths due to the exact thickness of the layers.
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.