How smart are you? I bet you can't answer my question!

[Bio-Hazard]

Alright, so this has to be the fifth time on the web I have asked this question. I've asked it a few times on the Internet already among some of the most intelligent people and they don't seem to have an answer for me. I suspect that only those who specialize in optometry or optical devices will have an answer for me.

HERE WE GO!

What are these lenses called?


They aren't see through. Remember, others can't see through these types while you wear them. This is what makes them different. These are coated just with enough "stuff" so that people can't see you looking at them.

What type of lens is it called? What is the coating called?

[GAHD]

you're talking about flash coatings.

The coating is actually only covering a percentage of the glass (about 30-70%) while the rest of the glass is untouched. think of it like a reallllllly fine screen they've fused onto there, that just happens to be reflective.

The side closest to your eyes probably has an anti-reflective coating (usually metal oxides) that stops it from being as reflective as glass normally is so it lets you see through easyer, and if it's an expensive type of glasses (say, oakley) it'll have a polorisation filter and molecularly bonded carbon deposited on top to make it scratch resistant (originally developped for NASA's Space suits' visors).

that help?

[Bio-Hazard]

Well not necessiarlys help fully.
The lenses seem to have a process done to them, but what are the lenses called.

I search google for flash coating, but only come up with plain sunglasses with a tint, not a metallic reflective mirror screen.

What makes this fine screen different than others?
Why is this more metallic looking than see through?

[GAHD]

Well, the reflective coating part i got from when i built a peice of electronics for my middleschool sciencefair project: Helium-Neon filled tube, producing Light Amplification (by) Stimulated Emission (of) Radiation (L.A.S.E.R.). The concept is pritty close: 2 tightly alligned mirrors bounce photons back and forth, but one of them is only 70-99% reflective, allowing some light through but reflecting most back(this is the basis for creating the standing wave of a LASER beam). This particular 'weak' mirror is coated in much the same way reflective sunglasses are, but to a higher tolerance. The anti-glare and anti-scratch coatings I know about from some article @discovery.ca ran atleast 5 years back. Polorisation filters I learned about when LCDs first started hitting the market and replacing LED components in home electronics.

[GAHD]

The metallic one is just metallic. it might be Chrome, possibly Silver or aluminum-oxide...it's just what they use for the flashing that makes it that color.

[cwes99_03]

My guess for the color of the reflection would be an aluminum oxide, if I remember my optics.
It is the same principle of any metalic reflective surface. Get in a dark room and place a light on the back side of the lense and you'll still see through it. Single sided mirrors are used in all kinds of applications.

All glass reflects some light back while transmitting the rest. Adding a metallic coating to the front side of the glass makes it reflect more. If the metal was a perfect reflector (i.e. the value of n=infinity? for the particular frequency of light) then no light could be transmitted through it.