Real UV flashlight

[Cyparagon]

Trouble is finding a suitable filter though!

Smash a $2 75W incandescent black light and glue a shard over the die I guess?

 

[Sigurthr]

Yeah that's probably the most economical. Ideally I'd want to find a thin wood's glass filter that has the same diameter as the torch window, then just either swap the window or place it under the window. I couldn't find any the right size though.

 

[Atomicrox]

Update!

Not sure if you guys already know but there are lots of feebayers selling 365nm 5mm LEDs. Seems to be different (and more expensive) than the old ones that did ~400nm. This guy (not the cheapest seller, BTW) even has a comparison picture.

I ordered a couple and will report back when they get here (probably a few months from now, don't wait for it..)

Received the LEDs!

Definitely different from the older ~395nm ones. These are more similar to the flashlight I have, though of lower power. They output of lot of visible light (which looks yellowish unless pointed at a fluorescent surface). With a grating you can see the whole spectrum and a stronger, broad "line" on the violet end but I'm not sure it's really 365nm. The fluorescence effect is cooler (though weaker) than the older LEDs because the output looks more "neutral" as opposed to violet.

If anyone knows of any household object that fluoresces differently from 365nm let me know and I'll test if this is the real thing.

 

[BShanahan14rulz]

Things that require extra security will often have features meant to fluoresce under the less common lower wavelengths while not doing much of anything when irradiated with +400nm. Maybe see if some high value paper money or personal checks or paychecks have some of these fancy features. I don't know of anything specificially, I don't have UV LEDs

 

[Atomicrox]

Tried paper money and credit cards. Both wavelengths work :/

 

[zyxwv99]

Try British or Canadian paper money. For example the words "Bank of Canada" over the portrait (in English and French) require 365 nm. Most of the other stuff on the same bills will glow under any kind of uv.

 

[Atomicrox]

I don't think I have either here, but I do have some foreign bills I could try. Will update on this later if it works.

 

[ImA4Wheelr]

I'm in a similar boat in that I purchased some 3w emitters advertized as 365nm. To me the visible portion of the light is almost neutral white. Pretty faint though. Not purple like some 395's I have. Things fluoresce more evenly or softly. Not as brilliantly.

I've been told the Canadian polymer bills are designed to fluoresce specifically at 365nm, but I have not been able to confirm that. So I haven't bothered getting any of those notes.

Security - Bank of Canada

 

[Sigurthr]

Bumping this for the addition of relevant data:

300-400nm Pass filters can be created by the combined use of two available photographic filters:

1) Schott S8612 2mm or thicker - Visible Pass (transmits 300-700nm)
2) Hoya U-360 2mm - Transmits 300-400 & ~715-950nm.

I have these filters myself for UV-only photography with a special camera sensitive to 280-1500nm. They are available in sizes ranging from 25mm diameter to over 70mm square sheets.

 

[Teej]

I've had good results with the Nichia NCSU033B LED - it puts out about 450 mW at the 365 nm peak, in my application.

For a single 18650 sized light, I find the visible part of the beam is minimal, but the florescence is excellent.

For my uses, a "perfect" 365 nm UV light will look like a broken flashlight, with no visible light coming out...and only florescent targets light up.

If there's residual "purple light"...that can wash out weak florescent effects for example.

 

[Cyparagon]

a "perfect" 365 nm UV light will look like a broken flashlight, with no visible light coming out

Except 365nm is visible. So if there was nothing visible coming out, the light IS a broken flashlight.