UV uses?

[EDcLED]

Very interesting! I am curious to know if any or all give off enough visible light to indicate power on in the absence of flourescing objects. I want one to play with.

 

[optolite]

live for physics...
what UV leds were u using to take those great pictures? wavelength.. flux?

 

[curtis22]

It would be nice if there was a UV-C LED for water disinfection. All the existing units use fluorescent tubes. Like this one.

 

[Sub_Umbra]

Very interesting! I am curious to know if any or all give off enough visible light to indicate power on in the absence of flourescing objects. I want one to play with.

Yes. As the light's wavelength gets longer (into NUV) more light is given off in the visible spectrum. For some tasks having a visible component can be a PITA but for others it may be handy.

If you are in an unfamiliar place using a light that gives off no visible light you may trip over something. Imagine trying to use a second flashlight (white) to try to see where you're going while you search for something with your UV light. Clunky. On the other hand NUV (Near UV) lights tend to provide at least some general illumination. It depends on what you're doing. Apples and oranges.

 

[liveforphysics]

optolight- The LED source is 378-381nm. To get blue flourecence, I have to get shorterwavelegnths, which is provided by flourecent tubes useing woods glass sleeves with a phosphor combo to yeild light between 340n,-380nm. Also a fairly heavy source of 405-425nm light from actinic T5HO tubes are used for a source to enable the greens and oranges to 'bloom'. Also, a 3.3kk and 6.5kk T5HO were on during those pictures, both tubes heavy in the 670nm area, with a fairy broad spectrum through the green and orange areas.


LEDlite- I would like to buy one of the aspherical UV LED lights useing 18650cells that you mentioned above. Could you PM me with how I can buy? Thanks.

-Luke

 

[2xTrinity]

If you are in an unfamiliar place using a light that gives off no visible light you may trip over something. Imagine trying to use a second flashlight (white) to try to see where you're going while you search for something with your UV light. Clunky. On the other hand NUV (Near UV) lights tend to provide at least some general illumination. It depends on what you're doing. Apples and oranges.
Reply With Quote

IMO a more important reason to have a visible component is so I can making sure I'm not hitting someone else's eyes with the beam, or with a specular reflection of the beam. These multi-watt UV point sources can't be healthy to look at, which is why the extent of my non-visible LED collection are little coin cell NUV LEDs for lighting up money. Either that, or I'd need to make sure that I and everyone else around was using some sort of UV-filtering glasses (for very short wave UV, even clear glass filters UV fairly well).

Now, a UV fluorescent light is not such a big deal in my opinion -- there the light is already diffused, so there's no chance of producing a pinpoint image of short wave invisible light on someone's retina.

 

[Patriot]

In addition to the above,

Some (all?) Scorpions can be seen very easily under UV light.

Credit/Debit cards have hidden logos visible under UV
Passports and driving ID cards often have UV visible markings

This is primarily what I use my two UV lights for. It seems to work well on all varieties of scorpion in this region. The bark scorpions glow especially white under UV light. I got stung by one while sleeping a few years ago and I really dislike them a lot.
:candle:

P.S. Liveforphysics, wow....very nice pictures!

 

[yaesumofo]

No rock hound should be without a UV source. It is fun to look at government issued ID documents as they all sem to come to life under UV. Credit cards light up too. Money, ****, all kinds of neat stuff.
I have a few uv sources but my best is a JIL with a cree uv emitter. It lights up the whole world of UV.
Have fun and DO NOT LOOK AT THE UV WITHOUT EYE PORTECTION!!!
Yaesumofo

 

[liveforphysics]

Patriot36- Thanks for the Kudos on my pictures!


As far as adding a visible light source with your UV source, you will really limit the ability to find the objects which flourece. As dark of an enviroment as possible with only shortwave UV light results in the highest contrast between the UV reactive things you are trying to find and surounding enviroment.

As far as worrying about the UVA from little LED flashlights at distances further than a few feet, you might be startled to know when you simply look down at a sidewalk on a sunny day, you can easily be getting hundreds of time the amount of UVA with some much more concerning UVB mixed in.

With UVA, you could damage your eyes if you stuck a 3W UV cree an inch from your eye and held if there for a while looking into it, just like you would have eye damage from a 3W white cree held infront of your eye looking into it for a few minutes... I belive you would actually be doing more damage to your retina from a white LED than a UVA led, as the UVA light would have a much higher percentage absorbed by the lens and fluid of the eye before ever reaching the retina.

Now, UVB on the other hand could becauseing cell mutations on your lens, and likely increaseing your chances of cataracts, and hours later, pain from the lens of your eye being irritated/burned if intensity and duration were long enough.

Again, these things really come down to common sense. Don't hold any intense source of any sort of emmision of anything in front of your eyeballs, and you will likely have an improved quality of life over those who do.

 

[2xTrinity]

Patriot36- Thanks for the Kudos on my pictures!


As far as adding a visible light source with your UV source, you will really limit the ability to find the objects which flourece. As dark of an enviroment as possible with only shortwave UV light results in the highest contrast between the UV reactive things you are trying to find and surounding enviroment.

As far as worrying about the UVA from little LED flashlights at distances further than a few feet, you might be startled to know when you simply look down at a sidewalk on a sunny day, you can easily be getting hundreds of time the amount of UVA with some much more concerning UVB mixed in.

My concern was more that the LED is closer to a point source -- looking at a blacklight fluorescent tube will cause your eyes to receieve a lot more total UVA, but it won't be nearly as concentrated. This is also why looking at a 5mm coin cell LED putting out maybe 5 lumens is a lot more uncomfortable than looking at 6000 lumen fluorescent fixture at the same distance. In the case of the sunny day, the UV light is coing to be very scattered, and the pupils will be constricted as well. However, you are right about the difference in intensity. A reflection of the sun off of a window etc. is likely worse than the flashlight in terms of UVA intensity. I suppose I'm overly paranoid about this stuff...

Again, these things really come down to common sense. Don't hold any intense source of any sort of emmision of anything in front of your eyeballs, and you will likely have an improved quality of life over those who do.

As an aside, have you ever had people who were curious about your lights point the light at their faces and turn them on? I've seen tons of people do that, seems similar to testing if a gun is loaded by looking down the barrel. A guy asked to see one of my Cree lights I carried with me (we were standing outside on a sunny day) he turned it on but the hotspot was barely visible as it was so bright out, so he looked right at the emitter to see if it was on then groaned

 

[mchlwise]

I sell a variety of UV indicator lights for pet urine detection.

The latest ones are 3 Watt Cree UV Leds with 2400 mah lithium ion rechargable batteries.

They also have glass Minolta aspheric lenses to produce the UV beam.

Difficult to take beam shot photos.

LEDite

Link? PM is fine too.

 

[mmmflashlights]

Hunting for **** seems to be a popular hobby.

 

[LightScene]

Several types of fungal skin infections will fluoresce yellow to yellow-green under 365 nm.

Yikes! All my toe nails are yellowish under UV, and some of the skin on the balls of my feet are too! This is a good diagnostic tool. I need treatments.

My Burton snowboard jacket has some unexpected fluorescent markings.

 

[Sub_Umbra]

I sell a variety of UV indicator lights for pet urine detection.

The latest ones are 3 Watt Cree UV Leds with 2400 mah lithium ion rechargable batteries.

They also have glass Minolta aspheric lenses to produce the UV beam.

Difficult to take beam shot photos.

LEDite

I'm another who wants to know more about your lights. Among other questions I have, are your aspheric lenses fixed or focusable? If focusable is there enough travel to really focus tightly as opposed to a somewhat backed off position which is de-focused to the point where most would discribe the resulting beam as "more useable."

 

[EDcLED]

I apreciate all the input!!

 

[jb1219]

Hunting for **** seems to be a popular hobby.

ROTFL...an astute observation

 

[PeterScowcroft]

I have been told that I need a short wavelentgh UV emitter to flouresce limestone but am unsure of the frequency.

Anyone have any experience of this or good tips?

Also what kind of result should I expect?

What I am hoping for is that I can see nothing but a shallow outline of the cave I am walking in, which should be enough!

What is the best SW UV emitter out there and how much power would I need to push to get a responce form limestone?

What is a good UV emitter supplier for UK?

 

[tulanebme]

I've also gotten to work with UV in constructing DNA microarrays ("gene chips"), protein microarrays, and in activating photosensitive growth factors. That was a 200 Watt mercury lamp, though. I kept a nice tan just from the glare coming off the filters and optics . They always save the hazardous type work for the graduate students.

 

[TeK]

Has anyone tried the Terralux 1W Cree UV for the MiniMag? After reading this thread I just need to buy a UV light... It seems that if you're not into pee hunting, you're not a good CPFer

 

[SoundMix]

... It seems that if you're not into pee hunting, you're not a good CPFer

From my little bit of research I've concluded that not all UV leds are up-to-the-task of being used for pee hunting.

I'll leave the explanations to the experts in this field.