Question about UV lights

icebeng · #1 08-29-2005, 11:34 AM

Hi!
I'm a newbie here so please bear with me.

I would like to purchase a UV led bulb to be put into a normal keychain light.
I've a couple of cheap UV keychain lights, but certain things that are supposed to glow under UV light do not glow when exposed to the light from the keychains.

I understand that the wavelength of the light has something to do with this.
The shorter the wavelength, the brighter the glow?
So here are my questions:

1. What is the wavelength of a normal flourescent UV money checker?

2. How low would the wavelength of the UV led have to be before anything that is suppose to glow will glow?

3. Any suggestions on where to buy such bulbs?

Thanks!

Lunal_Tic · #2 08-30-2005, 08:46 AM

Hi icebeng,

Welcome to CPF. Hang on to your wallet.

Here are some links that might help you out:

Where to buy small quantity of 365nm UV LEDs?
Dorcy 1xAAA UV mod?
UV led interest , might want to see this
Production UV LED lite fluoresce $100 bill strip?
**SOLD** Nichia HighPower 365 nm UV Aleph-19

I have been on this quest myself for a while. Hopefully I've got something coming in the post soon that will quench my thirst, however briefly.

-LT

Ken_McE · #3 08-30-2005, 05:21 PM

Some serious Nichia UV LEDs:

http://cgi.ebay.com/NEW-Nichia-NSHU5...QQcmdZViewItem

McGizmo · #4 08-30-2005, 05:49 PM

Those are good LED's but for point of reference, if you take best case of highest bin, they put out 2 mW of light. For a Real Serious UV LED, the Nichia i-LED UV 365 puts out a typical 100 mW of light! I picked up a few that are in the 130 to 143 mW output range.

If your needs can be met with a 395 nm LED, you really can't beat the Cree 7090 UV with close to 200 mW of output and at a cost that is about the same as a few of the good 5 mm LED's.

I know that the shoppe has a UV light using the Cree and I believe one or perhaps a couple of the supporting dealers are also handling both the Cree as well as some multi clustered units using the 5 mm LED's.

Many objects and chemicals will flouresce from light higher in pass band and in the visible spectrum. If your light source has significant visible output, you might want to consider a yellow or amber viewing filter to block out some of the visible reflected blue and violet light.

IsaacHayes · #5 08-30-2005, 05:56 PM

Is it true that the lower the wavelength LED, the less output they generally have? For instance, a 395nm 5mm LED will put out more mW than a 360nm 5mm LED?

Zelandeth · #6 08-30-2005, 07:44 PM

1. ~350-360nM. (For an F4T5 BLB tube).
2. The shorter the better. <400nM is really needed for good fluorescence.
3. See above posts, think that one's already been answered better than I can.

Just be aware that UV LED's tend to have shorter lives than normal LED's. Still good, just not as good as the 10-100K hours people tend to expect!

I still find that few things beat a good old fashioned BLB fluorescent for portable UV. Just so cheap for what they do, only real advantage I can see for LED's is portability.

Lunal_Tic · #7 08-30-2005, 07:48 PM

After using a UV light for 10,000 hours <I'd> probably start to fluoresce.

-LT

icebeng · #8 08-31-2005, 04:05 AM

Thanks people!

Zelandeth: Yes, the main reason is portability, I want something that I can put in my pocket or belt without weighing me down.

I've managed to find a source for 350nm leds, now could someone explain the following to me?

A: 30 µW @ 20 mA, 5 mm clear epoxy, 30° viewing angle

B: 15°, 50 µW @ 20 mA, TO-18 w. lens, Z-diode

I'm planning to buy one of these and sending it to Peak Led Solutions for a custom design Matterhorn. Would these fit?

Lunal_Tic · #9 08-31-2005, 07:32 AM

Well if it's built like a standard 5mm then it should fit. You might want to get more than one maybe 5 would be nice in a Matterhorn.

-LT

icebeng · #10 08-31-2005, 07:56 AM

Ha ha, no can do, LT, they cost far too much for me to get more than 1 or 2 at the moment.

The_LED_Museum · #11 08-31-2005, 08:51 AM

350nm UV LEDs in 5mm epoxy bodies cost $41.38 each, so having more than one would tend to be rather costly. :/

Lunal_Tic · #12 08-31-2005, 09:06 AM

Guess I was just thinking about how effective it would be with only one. In low light I guess it'd be OK. I was looking for something that would work even in pretty strong light so I was basing my advice on that.

-LT

IsaacHayes · #13 08-31-2005, 11:16 AM

If 360nm LEDs will do, you might want to check here. I have them and they are nice!
Click here Flux: 300uW +/- 100uW at 20milliamp, should be a bit brighter too than the 350's. They have a verry narrow bandwidth so they'll be pretty much 360nm only, without much spill into other wavelengths. Craig tested them and they don't loose intensity over time much if at all..

icebeng · #14 09-01-2005, 09:02 AM

Boo Hoo! Turns out the source I found doesn't have the 350nms anymore...

IssacHayes: Thanks for the heads up, these would be great and could potentially save me a LOT of $$$!

The_LED_Museum: I didn't realized you're THAT LED Museum! I found most of what I know now on your site! A big THANK YOU! to you!

Lunal_tic: What are you using your UVs for???

Lunal_Tic · #15 09-01-2005, 09:13 AM

I'm mainly interested in being able to check currency in daylight like outdoor markets; also hotel rooms when I travel but there are other things as well. From another thread:

Quote:

Lunal_Tic said:
Depends on the wavelength of the UV. At lower wavelengths you can see all sorts of stuff including all the strips in all the US currency. Also there are UV cure epoxies, soap scum and many mold and mildew types seem to fluoresce as well. Credit cards have UV logos and I've read that scorpions light up well. You can also really juice up your glow-in-the-dark stuff.

I've seen a UV lit water bottle that claims to kill nasties in water. I'm wondering if you could do that with a shot of wave-specific UV like comes from LEDs.

Whatever you do just watch for back splash; you've only got 2 eyes.

-LT

I was really fortunate to pick up a real gem from McGizmo. I've only had it for a couple of days but it is amazing.

-LT

The_LED_Museum · #16 09-01-2005, 09:28 AM

Quote:

Originally Posted by icebeng

...
The_LED_Museum: I didn't realized you're THAT LED Museum! I found most of what I know now on your site! A big THANK YOU! to you!

Thank you VERY much for your thank you!!!

:

icebeng · #17 09-01-2005, 09:50 AM

Quote:

Originally Posted by Lunal_Tic

I was really fortunate to pick up a real gem from McGizmo. I've only had it for a couple of days but it is amazing.

-LT

Could you tell me a little more about it? What kind is it? A bulb? A fully constructed light? The wavelength and (this might trouble you some) could you check to see if your passport reacts to it?

Thanks!

Lunal_Tic · #18 09-01-2005, 10:26 AM

icebeng,

I'll probably write something up about the McGizmo light later but for the mean time check the thread above about the Nichia High Power light. As for the passport, I checked an old one and a new one. Both have things on the pages that can't be seen with regular light; mainly colors or patterns and a few stamps in one.

-LT

icebeng · #19 09-01-2005, 10:53 AM

Thanks! LT!
Looking forward to your review!

IsaacHayes · #20 09-01-2005, 11:36 AM

LT - Hmm. so you picked up the one he was using to cure UV epoxy, the one with the wiz2 in it?

edit for clarity!

Lunal_Tic · #21 09-01-2005, 11:44 AM

Nope, I was the original customer for the 365nm A19. I pestered him for a good bit and he finally relented. It's a fine light too I'm quite fortunate.

-LT

IsaacHayes · #22 09-01-2005, 11:46 AM

Oh yeah there was someone before tvodrd he talked about building for. Ok so thats you! I get it now!

McGizmo · #23 09-01-2005, 11:47 AM

LT got the twin brother to the one that Larry bought. The form and function of LT's light encouraged me to build out the one that Larry picked up. I still have my "bench tool" but I also machined a one off PD head with a special bezel over the weekend which is now at the anodizer. This PD may become my bench tool.............

EDIT:
The UV light I use for curing the H3 vials has a wiz2 driver and it is the 2x123 light at the top in the photo below. It is a single power light:

Lunal_Tic · #24 09-02-2005, 05:46 AM

I can't remember for certain. Can I say that I have a review up in the Reviews forum as long as I don't link to it? I'm trying not to cross post but I also wanted to let people know about the thread.

In any event there's a review about the McGizmo 365nm light in the reviews forum.

-LT