Photochromatic & UV filter

[a1vo]

We all know there are "in-mass" and "imbibing" techlonogy to make photochromatic lens. ("In-mass" = whole lens change color. "Imbibing" = only the front layer change color.)

Also, we know that UV ray activate the color-changing feature of the lens.

My question here "Can all plastic photochromatic lenses block 100% UV ray?"

For in-mass + CR39 lens: I would assume the embeded agent in the lens absort the UV ray and hence "block 100% UV".

For in-mass + any high-index: I would assume since UV ray are blocked by hi-idx material, hence there are no such product exist in the market.

For imbibing + CR39: I would assume the embeded agent in the lfront layer of the ens absort the UV ray and hence "block 100% UV".

For imbibing + High-Index: I would guess front layer are made of CR39 or some other non-UV-blocking material, only the back portion of the lens are high index material. I do not know how manufactor resolve the optical problems raised when using different reflective index materials.

Can any experts anwer these questions?

[akeroptical]

I'm not trying to bust your chops but...

What exactly is your question?

[Chris Ryser]

Simple solution for your problem............................

Buy a UV meter and check them lenses and you will know if they block or not.

[chip anderson]

I've asked this before but if answered I don't remember the answer. If UV blocking eyeglass materials actually "block 100%" of UV. Why can't these materials or even these coatings be used in welding goggles and masks?
I suspect because they ain't even close to blocking 100% of U.V.

Chip

[Chris Ryser]

I've asked this before but if answered I don't remember the answer. If UV blocking eyeglass materials actually "block 100%" of UV. Why can't these materials or even these coatings be used in welding goggles and masks?
I suspect because they ain't even close to blocking 100% of U.V.
Chip

Because UV alone does not do the trick..................................

U.S. Department of LaborOccupational Safety & Health Administration

Regulations (Standards - 29 CFR)
Eye and face protection. - 1926.102


http://www.osha.gov/pls/oshaweb/owad...RDS&p_id=10665

[AWTECH]

Chip Anderson said:

If UV blocking eyeglass materials actually "block 100%" of UV. Why can't these materials or even these coatings be used in welding goggles and masks?

UV blocking is measured over a spectrum range. Typically today eyewear carries a 100% block at 380nm up to 400nm depending on the lens.

I have not yet looked up the nanometer range of UV blocking needed for welding but I get back to this and let you know.

Poly naturally blocks some UV but additional UV inhibitors are added.

Look for more information after Christmas, I am behind on the shopping and as you can see from the date and time of this post I need to get it wrapped up.

[a1vo]

What exactly is your question?

Sorry for the confision. My real quesiotns are:

How much UV-bolcking do plastic photochromatic lenses offer? As good as polarized lenses? (saw a website claim it is 100% UV blocking)

and

How do they make photchormatic lens with UV-blocking materials? Since UV rays are blocked by these poly/trivex/mid-idx/hi-idx material. This is like putting the lens inside a car, or is it?

[AWTECH]

a1vo said:

How much UV-bolcking do plastic photochromatic lenses offer? As good as polarized lenses? (saw a website claim it is 100% UV blocking)

I answered:

UV blocking is measured over a spectrum range. Typically today eyewear carries a 100% block at 380nm up to 400nm depending on the lens.

Polarized and UV are two entirely different types of light management throughout the visual and invisable spectrum.

a1vo said:

How do they make photchormatic lens with UV-blocking materials? Since UV rays are blocked by these poly/trivex/mid-idx/hi-idx material. This is like putting the lens inside a car, or is it?

Photochromics are activated by UV, with a transitions poly the photochromic material is bonded to the poly surface, so you are not blocking the UV with any poly material. I don't know of an in mass poly photochromic, and poly does have some natural UV blocking ability.

[Jim Schafer]

and did not have time to read all of the posts on this subject...gotta run but...

Welding and burning goggles/masks require IR protection..other end of the spectrum from UV.

Merry Christmas everyone!
Jim