What are CR-39 lenses made of?
CR-39, or allyl diglycol carbonate (ADC), is a plastic monomer commonly used in the manufacture of eyeglass lenses alongside the other material PMMA (polymethyl methacrylate).
Is CR-39 better than polycarbonate?
In comparison to polycarbonate, CR-39 provides vastly superior optics, rating just one rung below the material with the highest ABBE value: crown glass. On the flip side, CR-39 is the thickest and heaviest lens material.
What is CR-39 plastic?
An alternative material to polycarbonate is CR39 (Columbia Resin 39), a plastic polymer commonly used in the manufacture of eyeglass lenses. Unlike polycarbonate, CR39 requires a UV coating to be added to protect eyes from the sun’s harmful rays.
What is SV CR-39 HC lens?
Crystal Vision Enhanced CR39 SV Lenses This lens is a good choice for corrections up to +/-4.00, and it is available with a variety of options such as Transitions, Tint, Standard Anti-Reflective coating, and the top-quality Crizal Alize and Crizal Avance coatings.
Are CR-39 lenses polycarbonate?
Polycarbonate lenses have a higher index of refraction (1.586) than CR-39 plastic (1.498) and are therefore thinner in an equal lens prescription. However, unlike CR-39 basic plastic lenses, a scratch resistant coating is almost always standard as it is applied when the lenses are made.
Is CR-39 lens good?
That is where CR-39 lenses (Wikipedia link) improve on glass. It’s optical quality is almost as good as glass (and far better than all the other options we will look at), it is half as heavy as glass, it is much more resistant to shattering, and still very resistant to scratches.
Does CR-39 block UV?
Results: All the tested lenses absorbed all of the UV-B and at least 99% of UV-A. Conclusions: These data suggest that UV tinted CR-39 lenses provide protection against UV radiation that meets the ANSI Z80. 3-1996 Standard for non-prescription sunglasses and fashion eyewear.
What index is CR-39?
The refractive index of a basic plastic lens (CR-39) is 1.498 meaning that light travels 1.498 times faster in a vacuum than it does through the plastic lens. The higher the index of refraction the thinner a lens can be to get the same refraction effect.
Is CR-39 shatter resistant?
Polycarbonate is also even more shatter resistant, making it ideal for activities that have a strong risk of high impacts to your lenses. Though in reality this is not much of an issue, since CR-39 itself is quite impact resistant. The sales pitch of “shatterproof” is just that – a pitch.
How do I identify my eyeglass lenses?
Your type of vision problem will determine the shape of your lens. You’ll need a concave lens (curves inward) if you’re nearsighted. A convex lens (curves outward) will help if you’re farsighted. If you have astigmatism, your cornea is shaped wrong, so your lenses may be more like a cylinder.
Does CR-39 block blue light?
Advanced blue light filter technology Our top-of-the-range CR-39 lenses block up to 40% of blue light at 430nm and up to 100% at 350-400nm. The blue light blocking technology is also embedded in the lenses, instead of using a coating that deteriorates over time.
