Lens coatings, Materials, Types Flashcards
UVB wavelength
Most damaging to cells. Can cause sunburn, cataracts, and cancer.
Aspheric Lens
- Flatter base curve
- thinner/lighter
- minimizes distortion
- more attractive at higher powers
Anti-reflective coating recommended
UVA wavelength
associated with skin ageing, cataracts, damage to retina
Toric Lens
- 2 different curves, each has a different power
- the difference in curves gives the amount of astigmatism correction.
Atoric Lens
- front and back surfaces are Aspheric
- maximizes clarity of vision in periphery of lens in both meridians.
- called free-form lenses
Lenticular Lens
- strong plus powered
- Only lens center has high power, to minimize weight.
- Outer part of lens is flatter, has little to no power.
- Minus lens center looks slightly bowed-out.
Polycarbonate
- impact resistant
- UV protection
- Easily scratched
- thinner lens
Polarized lens
- takes scattered light, and filters rays into parallel beams reducing glare.
- Block UV rays
- Reduces visibility of LCD and LED lights
Phototchromatic Lens
- Activated by UV
- UV protection
- Do not darken behind the windshield, due to a UV blocking coating on the windsheild.
Bitoric lens
A lens with toric surfaces on the front and back
Coating that reduces glare, reduces eye strain, and can improve night driving.
Anti-reflective
Mirror Coating
gives lens same properties as a two way mirror. Anti-glare by reflecting light.
Trivex
- impact resistant
- creates fewer chromatic aberrations due to higher abbe value.
- better optics
- thicker in higher scripts
- Blocks UV
Lens tints
-solid or gradient
- available in any color desired
lighter for fashion
Darker used for Sunglasses with a UV coating
Abbe value
index of ref polycarbonate
abbe- 31
index of ref- 1.59
