1.56 HMC UV420 Blue Block Photochromic Lens Optical Lenses

Blue Block Lens: 

Photochromic: 
 

1. The definition of photochromic lens

Photochromic lenses, often called transitions or reactolights, darken to a sunglasses tint when exposed to sunlight, or U/V ultraviolet, and return to a clear state when indoors, away from U/V light.

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.

2. Outstanding Color Performance

1) Fast speed of changing, from white to dark and vice versa.

2) Perfectly clear indoors and at night, adapting spontaneously to varying light conditions.

3) Very deep color after change, the deepest color can be up to 75~85%.

4) Excellent color consistency before and after change.

3. UV Protection

Perfect blockage of harmful solar rays and 100% UVA & UVB.
 

4. Durability of Color Change

Photochromic molecules are equally bedded in lens material, and are activated year by year, which ensure durable and consistent color change.

You might think all of this would take quite a bit of time, but photochromic lenses respond remarkably quickly. About half the darkening happens within the first minute and they're cutting out about 80% of sunlight within 15 minutes.

Imagine lots of molecules suddenly darkening inside a clear lens. It's a bit like closing the blinds in front of your window on a sunny day: as the slats turn, they progressively block out more and more light.