We've added UV filter to our inventory. It's priced at $7.99 and is good long term insurance for your panel. This filter blocks 90% of all wavelengths lower than 390nm. It will be available from the store in the next few days.

But what is the trasmission rate of the film. Best I can find on the net is about 90% so that's another 10% of lumens down the drain? It this just a thin sheet we can sit in front of the lcd?

-Arkay.

The filter is very transmissive, I saw no loss of light whatsoever. It is very thin polyester acetate. To use it you can put it between your tempered glass and rear fresnel.

Does it have to be sandwiched like that? Could I put it on the outside of my sandwiched glass? I already have my glass siliconed together. Serparating it won't be fun.

Cheers,
Arkay.

I wouldn't put it anywhere else. Lamp side melt, in front of fres would be in the image path. I doubt you need to worry about it Arkay.

Hmmm. I'm not convinced.. I'd hate to kill my lcd with UV.
I'll just build it the way it is at the moment and possibly re-do the rear fresnel (with the blemish on it), and the filter at some later point. I'm assuming that the UV won't harm my panel immediately?

Cheers,
Arkay.

Unlikely that much will make it through the glass. If you decide to rebuild add it. The first thing to go if UV gets through is the blue color. My blue is very very deep and shows no signs of fade at all after 1000+ hours. Still for $8 might as well add a filter.

Brain, all,

is there a topic or thread that explains the use of U/V filters in our pj's? if so can you post a link for me?

tia

Sure isn't Tek but I'll make one.

Hi, can the uv glass be used instead of the tempered glass? Sorry if I this is a dumb question.

Sure can. ScottK I'll move the UV posts from your thread tonight.

thanks brain. i know you are a busy man!

i see you guys talking about a UV filter now. If im using the EYE should i get the UV filter and put it between my tempered glass and the fresnel to protect my screen?

yes a good idea, if you look at the picture of brains when he replaced the ballast with new ballast you can see his cap got a tan from the lamp, that is with i would imaginf 2,000 hrs on it. just think about what it does to the LCD or even the acrylic fresnels.

Before:
http://www.lumenlab.com/forums/index.php?s...=findpost&p=252

After:
http://www.lumenlab.com/forums/index.php?s...indpost&p=15634

Ok, i better add that to the must have list!

good idea man, i'm getting it also hopefully be shipped soon.

I know brain just finished cutting then to the correct size of the fresnels.

Joe

Is this some hardened piece of material or just a film that gets laid against the glass?

It is a thin film that you can place between your tempered glass and the fresnel.

Hello,

Brain when you say lower than 390nm, arent you talking about IR radiation?
im a little confused here 'cause i thought UV range was up there (faster or shorter wavelength)

and if im right do we need two filters, IR and UV?
how could this affect the lumens output in our projects?

sorry if i ask to much!

oh, another question, how big are the filters you are going to sell?

cheers!!!

This is actually Scotts Projector thread you may want to delete this post and add it to the Help section for brain to awnser.

Thanks, Joe

Good question. Since the wavelength is smaller the number is dropping, such as 390, 380, 370, 360 so we would say 'below' 390 if we are referring to wavelength. If we were referring to frequency it would be the opposite as the smaller the wavelength the higher the frequency. Makes sense right? (Not) Here's a diagram of the UV film's cut off wavelength.



The description of the film from the manufacturer: "A virtually transparent flexible polyester filter, specially coated to absorb ultraviolet rays. The material allows less than 10% transmission below 390 nanometers. 0.04mm thickness."


I'm looking into cold mirrors (IR block).

Is there a real problem in getting polycarbonate (Lexan) frensels instead of the acrylic lens?

Polycarbonate is much more durable, temperature resistant, solvent resistant (ie ammonia) and UV protective than acrylic. This would eliminate this UV sheet completely. Don't get me wrong. It is a thermal plastic, but its melt temperature is fairly high (~300 C; ~600 F)

This is the same stuff that is used with light-weight glasses, skylights, and greenhouses. It may cost a bit more, however I believe that it is well worth the investment when you are using an intense light and heat source.

Where do I order the UV filter from?

Brain will probably have it up on the store soon along with the Blackout cloth

Do the current OHP fresnels have any UV resistant properties?

OHP use a different bulb, and UV may not be as much a problem as ours, but the bulbs are expensive as well as short life period. Beside our fresnels are high quality OHP fresnels.

They should have some UV resistance. Not sure about what wavelengths though.

I guess that I have answered my own question with this document (295KB). It describes more about the frensel lens.

Fresnel Lenses and polymer types

It seems that polycarbonate has slight light transparency problems over time and is slightly more opaque than the polyacrylic lenses. I have seen polycarbonate car light enclosures that use the fresnel lenses, and have seen how durable they are. I was only going on what I have seen. If optical clarity is needed, acrlyic seems to be the best.

In this document, you can see the light range for each polymer type (Figure 9).

Sorry, I did not want to go off topic, however I am always curious why some things are better than others.

where and when can the UV filter be ordered?

Soon from the store.

Hello,
You can order the UV film from me now. I think the price was under $9.00 for the sheet. 20" X 24" plus shipping. Will double check.

I also have films to block IR heat and HEAT.
Send me an email.

what's the difference between these terms i've read about UV, UVA, UVB...and does the glass block any of the UV by itself? only reason i ask is because in my iguana's cage that glass would block the UV from the light.

The variation of UV (UV-A, UV-B, UV-C) are just ranges of UV light that are used to describe a spectral range.

http://www.physlink.com/Education/AskExperts/ae300.cfm

Glass by itself will not block UV light. Unless, it is UV filter glass. Generally, these are blue-ish in appearance. From the website below, it shows that you can get clear UV filter glass (untempered or tempered), however I do not know how much it will cost. I can only imagine that Schott glass = $$$.

http://www.us.schott.com/special_applicati...duct_range.html

Many polymers will be able to block UV light. This is how glass can block UV light by being laminated or coated with polymers. However in our case, the polymer coatings will be subjected to high heat, and it will not work at all with the pj. The polymer will deform and cloud over time.

Brain's solution, using the polymer sheet, is a good (and cost effective) way to protect your frensels and LCD panel. However, I don't know what the lifetime of the polymer sheet will be. I can only estimate it being at least as long as the the lifetime of the bulb (if not 2 or 3 bulbs), since it will be placed after the tempered glass (not too much heat).

Most plain glass will block UV wavelengths below 300 nm but not the entire UV spectrum.

http://hps.org/publicinformation/ate/q1851.html

Ordinary window glass is not very transparent to UV light.

http://www.newton.dep.anl.gov/askasci/phy00/phy00272.htm

Question - Can glass completely prevent ultraviolet ray penetration?
Does UV penetration depend on the thickness of glass?
---------------------------------
Glass is not a perfect UV blocker, but it is pretty darn good. ...

And yes, as you expect, the thicker the glass, the more UV it will block.
Basically, if thickness x transmits 50% of the UV, thickness 2x will
transmit 25%, 3x will transmit 12.5%, and so on...

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

http://www.newton.dep.anl.gov/askasci/chem00/chem00539.htm

Also, UV filter on the store now:

http://lumenlab.com/store/

I've cut a 3M FP200xl filter. Used on CRT monitor.

Do you think it would stop UVs?

I will try, but it's very hard (not to say impossible) to measure VU emitting. And I don't want to damage my LCD.

Brain,

Thanks for the helpful additional input.

Glass was not my forte'. I was thinking about quartz (crystallized form of glass) because it will allow a lot of UV through. But, I forgot that regular glass is not an ordered system, therefore it will not allow too much UV through.



Miles,

Do you mean the EF200XL? Or something similar?

http://products3.3m.com/catalog/us/en001/o...puterfilter_3_0

Yes, it will protect your screen from the majority of UV radiation, however it looks like a polarize polymer film.

http://www.physicsclassroom.com/Class/light/U12L1e.html

Personally, I would not use it because it will decrease the amount of light going through frensels. As a result, it will give you a darker projected image.

Exactly !



I get this filters for free, I'm not worry to make a try. I will tell you.

Give it a go, then. I am curious about the projected picture with and without the 3M film.

Another n00b question! my sheet got all finger-printed (heh, i forgot it was coming with my ballast, and i saw this brown envelope and reached in thinking "wonder what's in here")... Nice streaks I made.

Can we clean these with Plexus? Plexus is used to clean paintball goggles, because it does not deteriorate the protective chemicals used making goggle lenses... What about Windex? Should we avoid any kind of chemical cleaners?

No windex, just use alcohol.