I have an Osram HQI-BT 400W/D, and there is a "UV Filter" icon on the packaging. Do I still need to get another UV filter to protect my LCD and other humans?

also, would it be safe enough as long as there is no light coming directly from the bulb?
for example, if I have grills next to my bulb but they are pointed downwards, would this be safe if I were to look at the grills?

This question has been hashed and re-hashed. The lamps do put out UV. UV is harmful - to eyes and skin and plastics and other stuff too. Some lamps put out more UV than others. Ones that are clearly labelled for enclosed luminaires only (or some similar statement) should be assumed to be putting out a goodly amount of harmful wavelengths.

Member elken says - IIRC - most UV or mostly pure UV is emitted during lamp startup.

That said, it's very unlikely enough UV gets through all the optics to do anyone physical harm.

Do not look at your unshielded lamp without protection. Very short duration exposure won't hurt you much though. Don't stare into the triplet while the PJ is running.

Just as you wouldn't (I hope) stare at the sun or into a laser or into a very bright light you should treat your projector lamp the same.

As for your grill question - so long as you're not looking directly at the lamp from a very close distance and not exposing yourself for long periods of time to high fluence rates of direct lamp emissions you should be just fine.

Wear protective gear whenever running the risk of direct and close exposure to your lamp's emissions.

Hope that helps.

thanks. yes I think you are correct on what elken said, and I actually already know about the UV not getting through all the optics (I've done my homework).

I'm just having trouble finding a UV filter, and am worried if the claimed UV filter on the bulb is good enough.

I'm also worried about the relatively large amount of light that will leak out of the fans if I place them too close to the bulb.

With a little forethought you should be able to baffle and place the fans creatively such that you get very little in the way of light leakage anywhere near or towards where viewers will be sitting.

It will... if there's enough UV emitted at the source
ie lamps with no built in UV protection, especially short arc lamps...

But the question is does enough get through to be deleterious to one's health and well-being. Highly unlikely is pretty much the consensus. Without specific test equipment for each and every UNIQUE build and situation no one can really say with complete authority and assurance. We can say such-and-such component has a transmissivity of X% between Y and Z wavelengths.

Each and every post in a public forum has an implicit YMMV at the end.

Agreed, but I have seen quite a few people (myself included) complain of "eye pain" with certain types of bulb...
Mainly the ones that aren't UV filtered, to answer to the OP

For the record, LL recommends the use of a UV filter as a part of the projector design.

While the primary purpose of this filter is to protect the LCD from damage, it also does provide protection from such rays to the user.

General safety precautions shoud be excercised with the lamp at all times. There are serious dangers inherent with an operating lamp including burns and electrocution. There are several aspects to this design that can kill you if you do something stupid.

In the same vein, unshielded exposure to the lamp should always be treaded as potentially hazardous, whether the lamp is rated for an open fixture or not.

That being said, I am reasonably certain that the colour filters in the LCD will serve to limit the potential UV exposure to the user to safe levels, given commonly available LCDs. Naturally if you go modifying the LCD, or using exotic parts, your results may differ.

For myself, I am much happier knowing that I have specific UV protection built into the projector.

Highly unlikely, IMHO.

I err on the side of safety and I do have lexan XL10 as part of a UV filtering... and NEVER look at an unprotected lamp during any phase (starting up or any time while it is 'on')... common sense really.

cheers,
gs

thanks for the replies. I understand that it's always better to be safe, however, I am having trouble finding a UV Filter (and we don't have Lexans here). So far I've only been able to find small sized ones, like those meant for cameras or PDAs. I'm thinking of going with a lightbox design then, so that the only light leakage would be small enough to be covered by one of these.

Dont stress too much,,, it is only the direct light from lamp thats the hassle

and well as far as the LCD is concerned I dont think its much of a worry,, I will be soon acquiring a U/V detector to finally put this one to rest sometime soon,,, U/V's job in life is to make everything brittle by molecular breakdown...

the only part that may be of concern would be the blue filter in the LCD panel, this of course is provided you stay at or near 400 watts, I supect that above that, the rate is exponential..

light from triplet be fine,,, no U/V at that end of PJ

Have you measured yet?

My projector is behind a wall, so the only light I see from it is light coming through the optics...
I don’t believe that UV is a problem for the average build, but the statement that "no UV can make it through the optics" is one I will dispute until I see incontestable scientific evidence to support it

its simple the CF filters in panel alone dont pass it.. and its already reduced signifigantly by polarisers, and the glass in the panel itself,,

No such thing as an an ideal filter
How much UV is produced,
How much is blocked- 99%? 99.9%?
How much is too much??

Yes it is disputable, and I apologize for that. I was just doing a quick reply, so I got a little vague. A more accurate statement would have been "no harmful amount of UV can make it through all the optics".

Apology accepted
Waiting for Elken to acquire luxmeter and UV detector to make sure my eyes dont go too brittle

It is interesting and mildly disconcerting that some people do complain of eyestrain. To what might we attribute their discomfort? It's not necessarily UV exposure. Plus, take 100 people and expose them to the exact same conditions and some will experience discomfort.

As an aside last night I fired my new DE bulb on my M135 ballast to see how it performed. Prior to this I had only used an Ushio T15 Pulse Strike bulb no longer sold here. This new FC2 bulb stunk to high heaven (I would call it a distinctly ozone-like smell although some say ozone cannot be detected by the sense of smell - I think) and irritated my eyes greatly.

Ya think maybe - just maybe - some people are experiencing eye discomfort due to irritants other than UV exposure? Who's to say?

YMMV. (I think I'll add a disclaimer to my signature line.)

It'd sure be nice to actually measure UV.

Same thing happened with with my Osram HQI-TS... it smelled (not that bad though)... I was thinking the same about ozone... or even perhaps a "metalic" smell... I attributed it to the aluminum tape I started using at the same time, especially the adhesive. It will be interesting to see how the new LL DE lamp compares to the Osram in that sense. Didn't really notice it irritated my eyes that badly though...

I think so. Virtually all harmful levels of UV (this includes all UVC and UVB, and alot of UVA) would be blocked by a single pane of glass... add in several "layers" which include heat sheild, two fresnels, LCD (two polarizers, one pane of glass, one Color Filter), and three additional layers of glass in the projection lens and I think you'll find that virtually no UV levels remain that are harmful. You're likely to get more UV damage from being outside on a sunny day than from the light coming out the end of a projector... and we're not even dealing with direct view... we're dealing with front projection in which this is all reflected light.

The wikipedia contains a bit of information on glass, and it's ability to act a filter for UV light. Note that it says for normal glass, the higher grade glasses will pass UV radiation... and guess which glass our lamps are made from ? Especially the arc chambers... they are made from fused quartz (high resistance to heat), but do not block UVB & UVC. Lamps without an outer protective jacket to reduce these levels of dangerous UV are rated for "enclosed use", meaning they should be installed with a UV protective glass, such as tempered glass.

All that said, a simple UV measurement will put all doubts to rest... maybe... I wonder if the meter elken plans to use with be able to distinquish between UVA, UVB and UVC... there is a BIG difference in these levels as far as one's health is concerned.

cheers,
gs

hm yeah, I did smell something the first time I fired up my osram hqi-bt, but I don't remember doing so on subsequent trials.

anyway, iirc some people around here say that the tempered glass does not act as a UV filter, and that people use UV filter on top of the tempered glass. Yet, what you just said (about being blocked by a single pane) and the wikipedia entry contradicts that. so which is it?

edit: oh, the wikipedia says that glass blocks only partial UVA.

fully agreed, non-UVS bulbs hurt my eyes badly.
then the pain goes up to the brain, and it freaking hurts

as I understand, UVS bulbs block around 70/80% of UV, then the rest fades away while it goes through the tampered glass, fresnel and triplet.
so on your projection wall, the UV level is mostly harmless, and same goes for the LCD panel, as UV can damage it

It's also recommended to filter the UV of every light leakage, but well

This topic has some nice transmissivity info for various projector-related components.

on a related note:

anyone know if (some form of) Perspex would do just as well as the Lexan XL10?

edit: durachko, just found your post on march 15 regarding using Perspex VA. did you actually try it yet?

I'm also getting a UV detector, in a way. Not exactly a scientific instrument but, I think it'll (they'll) work...

I've ordered some "UV beads" from a company in Canada selling them on eBay. They haven't got here yet, but when they do, and when I get my PJ assembled (soon now) I'm gonna put some beads right near the bulb, after the fresnels, after the LCD and after the triplet. I'm curious to see how much they change color after each layer...

eBay auction.

Look like LifeSavers anyone with small kids knows where the name comes from .

photochromic specs might also work, I think they react to UV rather than visible light
...so if the movie's too dark you should think about getting out the sun tan lotion

PM me and expand on this a bit. I'm not quite sure to what you are referring. You could just post a link to that post here as well. Perspex VA isn't ringing a (loud) bell for me. If I had to guess I'd say I was posting some "synonyms" for Lexan XL10???

Incidentally, initially I will not be using any of the "conventional" UV blockers in my PJ.

I'm talking about this post.

Okay, I remember that now. Sure, that'd work. Nope - haven't tried it but all the data you need is there.

Read the follow-up posts to that for some more pro & con info.

At the end of the day you have to make your own choice as to what to do regarding a UV blocker. There are multiple options. I've been in your position (errr . . . I still am actually) and I understand it's hard to sift through and decipher all the myriad choices to be made when building your projector.

My personal opinion at this moment is that the way to go is to build a lightbox (or just a "wall") with an iris shaped to allow only "useful" light out toward the rear fresnel. I feel one of the best choices is Lexan XL10 for a UV blocker but I don't think it's entirely crazy to forego the use of a UV blocker. You may find you sacrifice component longevity but I can't say how long it would take to break down the rear fresnel, LCD, and/or front fresnel if you forego a UV blocker. Viable alternatives are glass with a UV blocking filter adhered to it, a hot mirror which provides some UV blocking, or this Perspex VA stuff.

Best of luck in your build and as you can see there are plenty of folks willing to give their opinions and assistance and we're just a post away.

I'm not that worried about component life, actually, I'm more worried about getting killed by my projector

but anyway, yea I'm going with a lightbox design. one last thing.. what good does normal acrylic do?

I know it won't do much UV filtering, but I'm wondering if it's still better to put it rather than nothing at all, or does it do nuts and as such I'm better off not putting anything?

Fear can be healthy.

There are two things to block - UV and IR. Off the top of my head I'm not sure of the IR blocking capabilities of acrylic but I think lexan is just a proprietary name for acrylic??? Can you say Google?

My mind is mush. The topic I referred you to above may have some transmissivity info for acrylic?

Edit: Errr . . . actually I think YOU referred ME BACK to that topic!

Edit #2: Wait . . . I mentioned it up even higher!!!

Just as an FYI, my new lilliput 8.4" is partly yellow from UV leakage. It happened in about 10 minutes of having my projector on. So personally recommend using atleast Lexan XL10 or whatever it is. JMHO

miedosoracing: which bulb are you using?

edit: just saw the info in your signature.

my main original question actually was whether or not the claimed UV filter on my osram hqi-bt would cut it.. not sure how it spiraled into this, but I'm glad it did

Durachko: no, lexan is not just a name for acrylic. Lexans are some kinda modified acrylics, in layman terms (i think). In fact, I think Lexan is just the brand. Acrylics are like.. plastic. but modified. heheh I'm not sure how to describe it.

Yep I'll say google or wikipedia. um.. I'd do it now, but it's late here and I gotta sleep.. maybe tomorrow morning.

edit: curosity got the better of me, and wikipedia-ing it was just a firefox search alias away. right anyway...


source: http://en.wikipedia.org/wiki/Lexan

wait, so plexiglas,lucite,perspex are all the same? wha-? I thought like Lexan they were modified acrylics as well. can't we all just call it the same thing? stop with the trademarking!

edit edit: decided to do a google as well, also just a ff search alias away.. I only checked the first link, though, and this is what I found:
http://www.fresneltech.com/graphs/acrylic_graph.html
seems like "general purpose acrylic" blocks off a reasonable bit.
hm so

Poor choice of words on my part regarding Lexan being acrylic. An organic chemist I dang well ain't.

The fresnels are made from acylic.

Lexan is polycarbonate. Polycabonates are much stronger than acrylic, and stands up to heat much better.

I did a type of litmus test using some UV stickers that came in a box of cheerios. They are normally supposed to be used on children (stick 'em on an arm or something) so that if they are exposed to UV from the sun, it's time to re-apply their suntan lotion. I put one in the light chamber, behind some flashing so as not to expose it to the direct lamp light, and another on the small piece of lexan that is holding my fresnel lens. Both stickers turned a darker orange color, indicating I should apply some sunscreen. The only thing between the sticker at the fresnel and the lamp is a crown glass condenser lens. I'm gonna take a picture then, expose the last sticker (only have 3 of them) to light coming from the triplet and see what I get there. I know this is really crude "test", and it doesn't tell us anything really about the type of UV they were exposed to, but it does tell me that some UV is coming through the crown glass condenser lens, which I suspect is mostly UVA, but i'm unable to verify with my "stickers". So, to be safe, and add some UV filter of some sort.

gs

cool, finally some tests

In this post you mention that UVF acrylic blocks 350-400nm of the UV spectrum. I'm also reading (here and there) that the XL10 blocks only >98% (so not 100%) of UV rays. does the lexan block the 350-400nm range as well as the UVF acrylic? I can't seem to find the transmittance info for the XL10.

I scanned XL10 in that thread. Checking now . . .

Edit: XL10 data and here too. Those scans give you all you need to know. Wavelength and % transmittance.

GS: Cut your stickers into smaller pieces.

Yes that's right, I'm replying to myself. What's that? Hey! You do NOT talk to me like that! You don't know me; I do what I wa'

Anyway. I've had those little beads for a while now. They're actually pretty darn cool!

When I first got them I was going for a car ride, while driving I opened my envelope and held the beads up to the sun, but they didn't change?! So I stuck them farther up the dashboard, still no change. Well after a little while I figured out that the car's windsheild was blocking the UV.

Anyway (2), out in the sun they change color pretty quickly, it's really cool actually! I also stuck them near my bulb (a 575w HMI) when it was on, they changed pretty much instantly! Yes, even at full brightness this thing is pumping -mad- UV! That's to say, the amount of UV didn't fall after the initial startup.
Very soon now I'm going to be, gasp!, actually building my projector. When I do (or shortly after) I'll put a few of the beads... oh wait, I already said what I'm planning to do... Well, suffice to say I'll have a little better of an idea just how far the UV makes it out of the projector.

I think I read a post a month ago where someone said that the extra envelope on the UV protected bulbs is in fact not always enough to block all UV radiation. I'll see if I can find the post and provide you with a link - If I can't find it then you're on your own LOL

EDIT: Ok I didn't find the post I was thinking of (if it even exists hahaha - the search continues) anyways here is another interesting post - see what elken2004 says:
http://www.lumenlab.com/forums/index.php?s...mp;hl=radiation

EDIT: Found the post I was thinking of:
http://www.lumenlab.com/forums/index.php?s...mp;hl=radiation

Maybe for those worried about UV, searching optical stores might help?

http://www.edmundoptics.com/onlinecatalog/...73&search=1

I haven't used it myself, but I plan on putting some of that between the light and the LCD.

(Edit: As Hidrudin points out below, dont use this stuff! - My bad)

That stuff looks horrable! The graph shows that it blocks 20% of the visable light also...

whoops! You are right. Good thing I am not an optical scientist. Then again, you have a umpteen kagillion watt bulb, how much could 20% hurt! (that was a joke, dont anser that!)