365nm UV Flashlight ... since I can actually see that wavelength! ;-)

I've been a lurker at CandlePowerForums for a while - some great info here - thanks!

So I recently had cataract surgery - at age 48, it was a few decades early ... but all went well. To make a long story short, I can now see in the UV spectrum - even got tested on a Monochromator at HP Labs - click here for my lengthy writeup with pictures and analysis about seeing Ultra-violet after cataract surgery.

So after playing around with a GE F15T8/BLB Black Light, I wanted to get a UV flashlight for more portability ... but wanted something at a low wavelength ... and ended up getting this Gallion Indium Nitride 365nm 9 LED flashlight from Amazon. I also got an el-cheapo 400nm UV flashlight - same form factor, but spills much more light into the visible regime.

It's pretty easy for me to test these (since I can see UV! ;-) as I simply compare what I see with/without a UV filter or polycarbonate safety glasses. Not much difference on the el-cheapo 400nm light ... but a significant difference with the 365nm light.

But the 365nm still "spills" a bit of light into the visible spectrum. I.e. I can see some light even through the UV filter. I'm wondering if perhaps the plastic cover (over the LED's) is causing this? I have tried to remove it, but even with pliers, it doesn't seem like that top will unthread.

This is a bit frustrating since it defeats the purpose of a 365nm flashlight ... and in this CandleForumPower thread, it seems other people have noticed this ... with one suggestion being to replace that plastic cover with Woods Glass.

Curious if anyone else has experience with these flashlights and any other suggestions on how to minimize the emission in the visible spectrum?

Thanks,
alek

:welcome: Alek

I had cataract surgery in 1997 at a similar age 44 due to side effects of medication, I read the linked article but I've never experienced any of the changes mentioned in the article.

I have a nice custom Peak LED Solutions 375nm flashlight and a flourescent UV unsure of the frequency (guessing 365nm).

No super powers using either light.

Norm

Welcome to CPF, alek

That's amazing - I never heard of anyone before who could see in the UV spectrum. Many animals (deer etc) can see UV, but you're the first human I've heard of (other than Norm, of course - don't believe his denial there, he has POWERRR, lol)

I just posted here about UV wavelengths, although I don't think that helps much with what you are asking. We've had lots of threads on UV in the past, and I'm sure other members will chime in.

I wish i could help you with the issue. Ive never had eye surgery but i can definatly see more into the UV spectrum than anyone i know. standard blacklights like you have in the writeup make my eyes burn, even with short exposure, for a couple hours. I need to use to UV glasses around any potential UV light sources other than being in daylight.

:welcome:

I can't help with the specific question but thanks for bringing this strange phenomenon, very interesting.

Maybe search after a UV light with "woods glass", that is supposed to block visible light.

That is amazing, I know that you can purchase UV LEDs (they are used in sensor bars for nintendo wii) you might be able to build some sort of torch yourself using these, that would be pretty awesome to go into caves or something with it and be the only one able to see... Did some reading and you are quite lucky, only two other people in the world (according to wikipedia) have been tested and verified as a tetrachromat.

i have few 360nm uv leds i too see the weak visible light emmited by them.
few times i had to use some eye drops that made me see a lot better in the dark, there was ancient mostly cave dwelling civilisation in peru iirc that used drugs which had the same effect but stronger, they could see in dark caves with no fire or any light source.

WOW! You have super powers!

I wish I could see the infra-red spectrum, so I have night vision :naughty:. No more need for red filters!

Wow! I wish I could see UV as well! So many things you could do...

Well I think a lot of people can see the light emitted by a UV light, but an IR light is a different story, can you see IR light? I have a UV flashlight and I can see the light if I shine it at the ground, but an IR flashlight I cannot. The only way I can see the IR light is if I use a camera.

I read your article on your post-cataract surgery experience and found it very interesting.

I had cataract surgery many years ago and am aphakic. Like you, I can see well into the UV spectrum. How far, exactly, I don't know.

But being able to see UV means that a good deal more of that shorter wavelength light is reaching your retinas, which is basically really, really, bad.

cbutters said:

tetrachromat.

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What a nice word

derfyled said:

What a nice word

Click to expand...

Word of the day ladies and gentlemen

FYI that a "tetrachromat" is someone who has 4 color channels - Wikipedia reference - which gives you much broader color discrimination - I don't have that ... and from what I understand, it only happens in women anyway.

My situation is similar to BigBluefish'es - it's the ability to see below 400nm in the spectrum.

Back to my original question, I guess what I'm wondering if I had a "bare" 365nm LED, would it emit much visible light? I.e. is what I'm seeing from this specific flashlight actually coming from the LED ... or re-transmission into the visible from the plastic cover?

You should be interested in this article then - http://neuronresearch.net/vision/files/photopiceffic.htm

"The common wisdom has been that the human eye has no ultraviolet sensitivity and that its response to ultraviolet light was due to fluorescence within the eye. This is clearly not the case."

alek said:

Back to my original question, I guess what I'm wondering if I had a "bare" 365nm LED, would it emit much visible light? I.e. is what I'm seeing from this specific flashlight actually coming from the LED ... or re-transmission into the visible from the plastic cover?

Click to expand...

Maybe not the best method, but this is all I can think of if you can't remove the lens:

Any photons coming out of the lens instead of the LED will be on random paths, not the original paths of the photons from the LED. So, any light emitted from the lens would be very floody, it's beam profile would be out beyond that of the light coming from the LED. So what you might be able to do is shine the light on a white piece of paper (or any uniform florescent surface) at very close range, and take a look at the paper. Any non-UV light light will fail to make the paper floresce. Combine that with the fact that it would be floodier, and if it exists, you should see a bit of light at the edge of the main part of the beam that is very dim (or possibly bright if there is a lot of light being absorbed and re-emitted by your lens) and does not make the paper floresce.

Of course, this is just speculation. I tried it with my UV light, and didn't see anything, so either my lens is perfect or my idea is off-base :shrug:

alek said:

. . . My situation is similar to BigBluefish'es - it's the ability to see below 400nm in the spectrum. . . . .

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Some people who can see <400nm see it as white rather than purple. I'm pretty sure it's mentioned in Fulton's work.
http://www.neuronresearch.net/vision/pdf/17Performance1a.pdf

MikeAusC said:

Some people who can see <400nm see it as white rather than purple. I'm pretty sure it's mentioned in Fulton's work.
http://www.neuronresearch.net/vision/pdf/17Performance1a.pdf

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Mike,

I quicky reviewed some of Fulton's work. Most interesting. There is quite a bit of discussion of UV sensitivity, so it's going to take me a while to go through it.

For me at least, the emissions for UV sources are distinctly purple. Ultraviolet lamps used for mineralogical displays, and those used in the food service industry (I believe to kill bacteria or viruses) give off a very obvious glow, and bathe the surrounding surfaces with a deep to medium purple, or light purplish-blue hue when viewed without looking through plastic or polycarbonate lenses, which both filter out some UV. Like the OP, I have also noticed on several occasions that certain fabrics (or more likely the dyes used in them) appear to reflect light in the UV range. What appears black or gray when viewed by me through polycarbonate prescription lenes, and when viewed by other non-aphakic individuals, appear distinctly violet, or even light-purple, when I view them without using glasses.

As to the OP's question, I believe another poster just started a thread regarding Woods Glass and 365 nm UV emitters. http://www.candlepowerforums.com/vb/showthread.php?316423-Woods-glass-filter-for-UV-light. Oops, not a new thread, just newly bumped by response, so perhaps, OP, you have already seen this.

Hello, it's very interesting to read about your ability to see in the UV - although I would be careful, as I don't know the response of the retina, but you may get getting a lot of UV in to see it, and they're very high energy photons, may not be good for the retina (the lens/cornea blocks the UV for most people).

If you want to eliminate any fluorescence and maximize the output from the device, then fused silica would work well, it transmits in the UV spectrum, where as most plastics/glasses block it.

You will probably struggle to eliminate all light from the visible spectrum, as the UV will fluoresce many materials, again due to the high photon energy. I have a 405nm laser pen (lower photon energy than 365), and although that's in the visible spectrum, very deep violet, it will fluoresce many materials to a bright blue, having said that it's a much more focussed beam.

Hope you eventually find your invisible torch, and perform the deeds you intend to with it :devil:!

Edit: Here are the spectrums for Wood's glass and fused silica, although fused silica is transparent in the visible, the visible light shouldn't exist as it transmits 90%, this means that very little is absorbed so shouldn't fluoresce.

Wood's glass does fluoresce and produce visible light, we know that as everyone can see when a blacklight is on or off.

Fused silica:



Woods glass: