Lexan does NOT filter out UV

[ace3000_1]

UV-P stands for UV protected , so its got a UV filter in it.

Trev

[dj_holmes]

NO WAY

so does that mean i don't need protection? but the funny thing is no body actually says how long usage damages colours. i mean say 150w hqi without filter on a 7" lilliput how long before damage roughly, 2 years 5 10 etc??

[ace3000_1]

Ya you dont need another filter, having another filter is more or less pointless.

Im not sure how long a lcd can last without a UV filter, but ive had a halogen fade a lcd and frensel before after about 300hrs of use without one.

Ive clocked up way over 2k hrs in testing, and my lcd looks the same as the brand new spare i have using bulbs with a uv filter.

Trev

[dj_holmes]

well you sure are smart and smart people benefit in life...i just saw your 7" lilliput projector...wow...hello some serious business!!!!!

u just helped me in more ways than you know

take it easy mate

[ace3000_1]

Thanks for the nice words DJ . That projector in the other thread is old now, ill have the new up soon, there has been manny changes. Ill post up the projector when its done.

Have a good one buddy.
Trev

[TaskMaster]

If you say polycarbonate doesn't block UV and that is a fact, I would have to agree... an incorrect fact.

Polycarbonates are, as the previous quote stated (about Lexan), "essentially opaque at all wavelengths below 385 nanometers." Coatings and additives are to protect the polycarbonate, but with or without them, polycarbonate does not transmit UV. Without protection the polycarb will degrade over time, but still it will not transmit the UV spectrum. If you find this hard to believe take a piece to an optician and see for yourself.

DJ_Homes - Just to be clear, it doesn't just block some UV, it blocks virtually all. If you look at the graph MegaMan linked to it shows the same data. I am just stating fact you can verify in any Engineering Thermoplastics Handbook.

Whatever you want to call it, polycarbonate by any name still blocks UV.

[ace3000_1]

If you say polycarbonate doesn't block UV and that is a fact, I would have to agree... an incorrect fact

If read back in my posts, i never said it didnt block uv, i told you its not a UV filter.

Whatever you want to call it, polycarbonate by any name still blocks UV.

.....at different levels at different grades, just like glass or any other optical medium.

Trev

[TaskMaster]

Originally posted by ace3000_1
All of our $39.00 complete pair packages are made using polycarbonate lenses; the lightest, most impact-resistant material made. With an index of refraction of 1.59, they are much thinner than standard (CR39) optical lenses. They also come with both 100% UV and tough scratch-resistant coatings applied to both sides of the lenses, as well as polished lens edges, at no extra charge.


If Polycarbonate filterd UV in a resonable standard, then tell me why they state here they coat their polycarbonate lenses with a UV coating.

http://www.39dollarglasses.com/info_pop/lenses.html

Trev

Since you asked: lenses are coated because unprotected polycarbonate is degraded by UV, but regardless, it still does not transmit it. The coating is to protect the lens only. That is why it is applied to both sides - otherwise why would you coat the inside? So peripheral UV coming at the lens can be better reflected into your eye?

[TaskMaster]

Originally posted by ace3000_1

.....at different levels at different grades, just like glass or any other optical medium.
Trev

Nope, all grades of polycarb have the same polymer chain which is responsible for the UV blocking charateristics. Call it a blocker, call it a filter (I am using the terms interchangeably), UV doesn't pass through the plastic to the other side.

[ace3000_1]

Since you asked: lenses are coated because unprotected polycarbonate is degraded by UV,

UV stabilised polycarbonate isnt. How do you know they use a Polycarbonate thats not UV stablised?

That is why it is applied to both sides - otherwise why would you coat the inside?

The coating is there so the UV filtering can be at a higher level then what Polycarbonate realy is in its native state, its to save your EYES!!!

The coating on the back is to filter the reflected light going back to your eye from angles on the sides.

As stated before search UV400. If polycarbonate was so great in its native state, then why is there UV400 in optical glasses?

Trev