We left off in Part one by saying we are going to explain in Part two how to tell if your eyeglasses have anti-reflective (AR) coating. Here's how:
Hold the glasses parallel to the ground, with the temple arms (the stems that go behind your ear) up or down. Angle the glasses so you can see reflections on the lenses. If the reflections look green or purple, your lenses have AR coating.
Here’s why: The reflections will look green or purple, or both green and purple, because AR coating blocks waves that are in the green-to-purple wavelength of the spectrum of visible light. That’s why these colors are reflected on the lenses.
But there’s a big difference between standard and hydrophobic and oleophobic AR coatings.
The hydrophobic AR coating is called that because although it blocks reflections the same way the standard AR coating does, it’s also water (hydro) resistant (phobic). It puts a slick surface on the lens that resists the buildup of water-based moisture, which is important to have when you’re watching a tearjerker like The Best Man Holiday for the 87th time.
The hydrophobic and oleophobic AR coatings make your eyeglasses’ lenses easier to clean than lenses with the standard AR coating. You can do this experiment yourself. If you have a pair of glasses with standard AR coating and a pair with hydrophobic or oleophobic AR coating, clean each pair with the cloth that comes with your glasses. It’s much easier to clean the hydrophobic or oleophobic pair than the standard pair, right? The cloth slides right across the surface of the hydrophobic- or oleophobic-coated lenses, while on the pair with the standard AR coating there’s a little drag on the lens.
The oleophobic AR coating is called that because in addition to resisting water the way the hydrophobic AR coating does, it also resists oil and grease (that’s the “oleo” part, as in “oleomargarine,” which is what margarine used to be called).
The oleophobic AR coating has a slick surface on the lens that, like the hydrophobic AR coating, resists the buildup of water moisture on the lens and makes the lenses easier to clean than lenses with the standard AR coating.
But it also protects against smudging from fingerprints as well as facial oils. That's the lowdown on AR coating.