Hello
Decided to try one cheap,interesting LED from Buyincoins. The LED is named shortly “CREE 5W White Light LED Flashlight Torch Emitter Bead 410LM With Samsung Cell”
I have already cool white Cree XP-G2,XM-L and XT-E leds,so I ordered the warm white version. The LED is high quality,very bright with very homogenous beam.The shape is almost the same as the Cree XP-G2. The tint is the same as the old incandescent bulbs. It is way to warm white for my taste and I decided to experiment with the led.
First was de-doming to see how the beam will change.Narrower beam and the same tint,not warmer.
Here is dedomed(forgot to take picture with the dome on)
Next step- Decided to remove the phosphor(I always have wondered what’s underneath).
I took a sharp knife and cut the phosphor carefully. And here is the result: Nice,dense Blue/Violet light. Very bright.
I am impressed how bright the GITD and fluorescent objects glow exposed to this light.
The only question is how safe is this light to our eyes?
Is it the blue light that reacts with the fluorescent paint or there is a high UV emitting too?
I drive it at 700mA. It could be driven also at 1,5A.
I mounted it in a cheap “Police” flashlight/host.
The camera has big problem to catch the real look of the Blue/violet beam. It is not quite sensitive to it.
The bright center of the beam is blue/purple color, not white as it looks in the picture below.
Here is the beam compared to the 100Lm Low mode on Olight R20 with a XM-L2 in the same size reflector.
5 meters distance. 1/6sec
Edit:
Bought the cool white version of this LED,too. I little too greenish tint,similar to the cool white XP-G LEDs.
Trying to re-solder it to another board,I drop it on the table over a wooden pad and unexpectedly,the dome just fell off.
This was really easy and unwanted de-doming process The board was not so hot to melt the silicone dome.Seems like the dome was just glued to the emitting surface. As expected the tint did not got better.
Great project and great pictures!
2W of UV light is a lot. I wouldn’t use it without protection glasses…
There are different types of UV (close to blue or not). Maybe that someone with knowledge in that sector can answer you more precisely.
My camera can’t catch it well. In real life the beam looks purple without comparing to other source,but compared to a 5mm UV led looks more like a blue color.
Have no idea about the wavelength and I wonder how much of UV emits.
Well, the led is clearly a Samsung 3535 led, so it is not correct that the name Cree was used by Buyincoins. Good to see that it dedomes so well.
I am also interested in the wavelength of the led under the phosfor, I do not know of a white led that uses a blue led under 450nm, while uv starts at 400nm (and lower). I could be behind on latest technology, but a 400nm emitter, as far as I know, has not enough efficiency to make a competitive white led of.
Justast week I read a thread where someone measured (with a DIY kit spectrometer) a white Nichia with the phosphors layer damaged and there was a surprisingly high amount of UV so I imagine this has some real UV, not just purple. FlashLion do you happen to have any lights with Royal Blue emitters to compare it to? If I had a samsung 3535 I’d do it myself, I have lots of royal blue emitters I could compare.
Too bad I don’t have a high power blue led and can’t say for sure the color of the modded led.
Thanks for the info djozz
I am not much into color LEDs and different wavelengths. Sorry if my comments are not quite correct :~
Corrected the title of the post.
I am impressed how actively GITD parts and fluorescent paint react to the this light,even at long distance.
Does the fluorescent paint react actively to the royal blue light?
Edit: I think I answered my question. Found a 3mm blue LED. The fluorescent/luminescent painted objects emit under blue light.
Hope the modded LED is not so dangerous to use when it is not specialized only UV.
Second EDIT:
Compared this de-domed LED to a flashlight with a blue filter and also to a UV 5mm LED (have no idea what wavelength).
I used for the test money and ID card with an invisible marking. And the result is-the de-domed Samsung LED does not activate the hidden marking. The 5mm UV led does it.
So,the de-domed led probably emits negligible percent UV light that is not dangerous.
if i recall correctly for Phosphor to become fluorescent & emit white light it requires Ultraviolet Light under 365nm. I might be wrong, but i thought i read somewhere that the base emitter emits in the 345nm range, which can be dangerous to the eyes at high output levels.
It’s definitely not UV. White LEDs like this use a die that emits what usually called “royal blue” which is in the 450-465nm range. It’s still not great to stare into it, but certainly not as dangerous as UV would be. Also, it’s not possible to have some UV and some blue; single LEDs only emit in a very narrow band of wavelengths.
Or take it to your eye doctor — many of them have a UV light meter, to test whether UV gets through a protective coating — whether it was put on lenses properly. They’ll tell you how much risk there is.
Do get those annual eye checks. There are several things they check routinely that have no symptoms you’d notice ’til too late.
Seriously, look it up with Google at least.
Relying on memory and opinion gets us what we learned in the past.
“It’s a poor sort of memory that only works backwards”
I’ve quit giving my opinion because when I started looking up what I think before posting it, almost every time, I find a lot has changed since I learned much of anything about almost anything.
May not be true for you. That’s my experience.
So I won’t tell you what I think, I’ll tell you why I think it’s a good idea to look up both — blue and UV.
I did. I take precautions.
— use the spectrometer kit, or get yours checked some other way, or behave as though it might do you harm when you don’t know for sure.
Emitters aren’t single-wavelength devices.
Basically any photon that packs enough energy to knock an electron off an atom.
The shorter the wavelength, the higher the energy. That’s what causes problems. That’s what causes phosphorescence.
If it lights up your socks, it may add up to damage — not immediate, doesn’t cause any pain, but it adds up over the years.
Thanks for the link hank
I don’t know how I missed this thread and it’s posted a few days ago.
I checked the Wikipedia about UV light. Too many questions came to my mind.
One of them- if the “black light” is ultraviolet,why is used so freely in galleries and dance clubs.
This picture from Wikipedia is titled “A 380 nanometre UV LED makes some common household items fluoresce”,
but we can see a lot of visible light from a 5mm leds.
Because there isn’t any real regulation. Those that use & sell blacklights will of course fight any regulation. Perhaps regulators don’t yet feel they have enough indisputable research to face the fight.
Laws and regulations lag way behind health research.
Many risks — serious concerns — are statistical risks — problems that show up in populations over enough years, not hurting a few people on every block every week. Most of the things that would strike you dead immediately have been dealt with. Stuff like this comes out of epidemiology.
Or, of course, chemistry: You know not to mix ammonia and bleach, right? But it’s not illegal to sell either of them. Or have them both on the same shelf in the bathroom. (Kids, if you don’t know, do NOT try this at home to find out why. Seriously, Google wants to be your friend here)
The blue light hazard is both — epidemiology and biochemistry, both fairly new science — as you see from the Google Scholar search.
Just saying — look into it, think about it, don’t expose kids to it (age makes a huge difference in exposure).
Another thing I just learned (looking up what I thought I knew!)
The visible light we see from “UV” emitters (around 400 nm) is a tiny part of the energy — almost all the energy is just beyond the limit of normal vision, around 375 nm:
… An ultraviolet LED will put out most of it’s light in the invisible near UV range, with it’s major output around 375 nm, just outside of our range, but with a smaller output around 400 nm, or just within range. For this reason, to the naked eye an UV LED or a blacklight looks pretty dim, but really they’re pumping out quite a bit of light that you can’t see. Here’s a chart from wikipedia to clarify.
That instructables is quite wrong. He is mixing UV leds with Fluorescent black lights.
The peak wavelength & spectral width can often be found in a particular led’s datasheet. Usually ~ 10-20nm spectral width (½ of the peak intensity) for UV leds.
Not to make the point that blue and uv is nothing to be careful with, but (I think I posted it in another thread as well):
We are exposed to the sun all our lives (truckloads of blue and uv, including deep uv), we do narrow our pupils because of the combination with other visible light but the amount of eye damage by the sun outweighs everything else we encounter normally (and our eyes still more or less lasts a lifetime), you must do fairly stupid things with leds to surpass that (like willingly looking into the emitter for fair amounts of time).
My own experience with several uv-sources is that I can feel the really nasty uv-radiation as physical pain on the retina, and I know to back off then. Wall reflections from my Led Engin LZ1 365nm flashlight mod do that if I shine it around in the living room for a minute. It does not mean that if I do not feel that pain, that no damage is done, I am aware of what happens.
Bottomline for me: I'm not paranoia about blue/uv exposure, I accept that some eye damage will occur (I will probably die of other causes), but I am aware when using these light sources.
Nice,dense Blue/Violet light. Very bright.
The board was not so hot to melt the silicone dome.Seems like the dome was just glued to the emitting surface. As expected the tint did not got better.
