A strong bright headlamp

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Postby werewolf » Jun 10, 2006 2:52 pm

Ralph -

If you read it it says that the difference between lasers and the new LED's is becoming indistinct. I don't think your interpretation is correct. I mean "someone stupid" can abuse ANYTHING and hurt themselves. In a cave, your eyes may be fully dilated - and then getting flashed with a super-bright LED [CENSORED] laser...

Years ago I looked directly into an infrared flashlight, the kind used with night vision. The light is totally invisible to the human eye so the flashlight looks like it's off when it's actually on. I started getting sort of a fireworks sunburst effect in my eye at about that time. I only see it in the dark. I've been to two retina specialists since then. They both said I do not have a detached retina (which can cause this symptom). I don't know if looking into that light caused the problem, but I think it may have.

And then you got the homicidal maniacs in the military deliberately making laser blindness weapons - and you know that sooner or later they're gonna want to try out their new "toy"...

Scary f'ing planet. Beam me up, Scotty - I've seen enough!
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Postby Realms » Jun 11, 2006 3:40 pm

I don't think my light can be considered "weapons grade" I do like it though.
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Postby Nico » Jun 11, 2006 6:15 pm

interesting rig Realms, I'd be interested in something like that.. how much would they be if you were to sell it?
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Postby Realms » Jun 11, 2006 6:33 pm

somewhere in the neighborhood of $250
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Postby potholer » Jun 14, 2006 7:33 am

For a wide-angle-emitting LED, I'd have thought its potential for causing damage was very much in the ballpark of low-power halogen bulbs.
A 1W LED giving out ~40 lumens of visible light with little/no extra UV or IR and emitting from an area of many square millimeters would seem to be comparable to a 2.4W halogen bulb giving out ~40 lumens of visible light and a large amount of IR, emitting from a filament with a similar (if not smaller) apparent area.
In fact, given the relative lack of invisible emissions, I'd have thought the LED might even be rather safer.

There may well be some power/area level above which permanent damage might be an issue, but as long as something is *only* giving out visible light, I'd guess (hope?) that discomfort and/or persistent afterimages would tend to make people cautious of looking at things before they reach that limit.
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Postby karst97 » Jun 20, 2006 9:08 pm

Realms wrote:Its a 9 WATT setup (3-3watters) It has active cooling and has ran over 7 hours so far with all three lights on full power with no dimming.
Nathan


So that's over 63 watt-hours of battery power... That's a lot of (larger) batteries...

Let's see... about 21-23 2.5AH AA cells.

What is your dimming range?

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Postby Realms » Jun 20, 2006 9:49 pm

Right now I'm using 20 2.5AH NiMH AA size batteries. This was really only intended for prototyping purposes. I am switching over to dual 14vdc 6.5 Li-Ion bats. Total of 13AH as opposed to my 5AH setup now. The power driver does have leads for a dimmer however at the moment I'm not using it. Also as long as the light is used in a cave environment it does not need the active cooling that was going into it. The 5watt array is a different story.
It is amazing to run it for several hours and feel that the aluminum block is still fairly cool the run it outside of the cave and feel the temp start rising considerably.

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Postby werewolf » Jul 1, 2006 11:36 pm

I asked the eye doctor - and he's a nationally prominent eye doc - if looking into a powerful LED flashlight could cause permanent eye damage. He said that he didn't think so because they are careful about consumer products and eye damage and he has never heard of such a case. I also asked him if that little eye problem I got could have been caused by looking directly into that infrared flashlight. He said that yes, it may well have been, as it seems to be a laser - it casts a very narrow and concentrated beam of (infrared) light a long distance.

Looking into a laser can cause permanent eye damage. But then the distiction beteen lasers and high powered LED's is getting blurred, isn't it?
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Postby Mark620 » Jul 5, 2006 7:42 pm

Yes it ia all mounted...the stenlight battery is not on the helmet.

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Postby hank moon » Jul 5, 2006 8:43 pm

werewolf wrote:I asked the eye doctor - and he's a nationally prominent eye doc - if looking into a powerful LED flashlight could cause permanent eye damage. He said that he didn't think so because they are careful about consumer products and eye damage and he has never heard of such a case.


Not a very satisfying or thoghful reply, eh? Cars are consumer products and several of them have been defective enough to cause many deaths over the years. Some examples:

http://www.citizen.org/congress/civjus/ ... fm?ID=9361

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Postby hewhocaves » Jul 5, 2006 9:26 pm

you could probably come up with a crude set of experiments if you got some sort of statistics about the average criteria for eye damage. i'd be curious to see what those results would be.

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Postby paul » Jul 6, 2006 6:34 am

Interesting - I found this page yestarday and it has a section where it says "LEDs are dangerous to your sight" - see the section titled "Drawbacks of using LEDs"
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Postby NZcaver » Jul 6, 2006 1:15 pm

paul wrote:Interesting - I found this page yestarday and it has a section where it says "LEDs are dangerous to your sight" - see the section titled "Drawbacks of using LEDs"

That article makes interesting reading, although some of the information is definitely a little dated. I'm thinking it was written at least a few years ago, based on comments like "backed by practical tests of our own lamps, our suggestion is that you need at least 24 LEDs for a 'main-beam' lamp." 5mm LEDs have more than tripled in efficiency in the last few years, making the 4 smaller LEDs in a Princeton Tec Apex - for example - perfectly adequate as a main-beam lamp. And there is no mention at all of the 1 watt plus high-intensity side-emitting LEDs, which are now common in headlamps.

Nevertheless, some good information there. Sure it might be possible to damage your eyes with prolonged exposure to one of the really bright LEDs, but being "flashed" on many occasions by them hasn't seemed to do me any harm at all. Still 20/20 vision, and not too many hallucinations. :wink:

Here's a site I often use for reference on headlamps and flashlights - http://www.flashlightreviews.com/
I couldn't find anything written about eye damage, but there are several good articles about LEDs and other lighting under Q&A.
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Postby potholer » Jul 6, 2006 1:45 pm

In the 1Watt area, I don't see how an LED is likely to be more dangerous than a ~2W halogen bulb. The LED is putting out about as much visible light from about the same emitting area, but the bulb is possibly pumping out rather more IR than visible light which, (if the IR isn't absorbed by the optics) could result in the filament bulb dumping more energy into a target.

I'm not sure *any* LEDs are perfectly focussed by their optics, which presumably means they get less intense the further away they are, and even optics giving a largely parallel beam do effectively also give a larger emitting area than a bare LED.
I suppose with side-emitters that the peak emission area can be a relatively small disc on the reflector, but even then, it still covers *some* area, and who would look directly into a spot-beam for long, given a choice?

*With* bare LEDs, ironically, an unfocussed Luxeon with its wide-angle emission might be no worse than a rather dimmer 5mm LED with a narrow beam angle viewed from the same distance, even if the Luxeon is bright from many more directions.
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