|1.56 Photochromic Semi Finished Lens|
|Material: 1.56 Index Resin(Ne=1.549, Abbe value=43, Specific gracity=1.14)|
|Color: Brown, Gray|
|CONVEX SURFACE||CONCAVE SURFACE|
|Mominal Curve||True Curve||Sag(sagitta: 40mm)||Sag(sagitta: 50mm)||Radius||Radius||CT(mm)||ET(mm)||Dia(mm)|
1) What are photochormic lenses?
Photochromic lenses are made of many lens materials including plastic, glass or polycarbonate. They are typically used as sunglasses that conveniently switch from a clear lens indoors, to a sunglasses depth tint when outdoors, and vice versa.
They typically take around 30 seconds to fully darken and approx 2 - 5 minutes to return to a clear state.
Photochromic lenses were created in the 1960's at the Corning Glass Works Inc, and became the first variable tint/photochromic lenses brought to the marketplace.
2) How do photochromic lens work?
A chemical process takes place when exposed to sunlight/UV and the molecules effectively move, change shape and absorb the light. This process changes the molecules and they darken to a sunglasses shade/tint.
The photochromic lens will remain in this 'darkened' sunglasses state whilst exposed to sunlight/UV and the molecules will reverse the process once the lenses are removed from the sunlight/UV rays returning to the original 'transparent/clear' lens.
3) The advantages of the photochromic lens:
FASTER, SAFER, BETTER
The photochromic lens introduced people to the balance of wearing one pair of glasses for both outdoors and in. Today, Transitions lenses rapidly filter light with industry leading photochromic dyes whilst blocking 100% UVA/UVB rays.
The coating used and the curved nature of lenses mean that up to 10% of light can be lost through reflections at the lens surfaces, these reflections can be distracting and appear unattractive.
By adding a coating it allows around 99% of light through the lens resulting in increased visual comfort and performance.