18650 365nm UV torch recommendation

[Olumin]

I recently read through the "best UV flashlight" thread by 7histology, and that made me curious about UV lights, since I don't own one myself yet. I am not well versed in UV torches and emitters, and sadly the thread didn't really come to a concise conclusion either about what really is the best UV light out there. So I'm gonna attempt to narrow down the scope of this admittedly very broad question a bit.

I'm looking for a quality, 365nm, preferably single mode, pocketable, >3000mW, UV flashlight with regulated output that runs on a single 18650.
- Glass lens, no acrylic.
- Rear forward clicky.
- Little visible light spill OR compatible with a visible light filter (that can be installed without modification).

The most interesting I've come across so far is the Fenix tk25uv, which seems to have a simple enough interface (and is in fact a one-mode light when switched to UV) and meets my requirements in terms of output. Only thing about it is the white-light capability that would be quite useless to me. Ideally, I'm looking for a Pure UV torch. I am also unsure as to the quality of the UV emitters used. What quality UV light can one expect, how much VL spill?
The Malkoff MD2 UV appears interesting, but seems a tad under-powered with only 1800mW? Also, so far as I know, MD2s use acrylic lenses. It is also unregulated below 3,8V, so that's no good either.

Is there anything better out there? Can anyone vouch for the Fenix?
I am of cause aware that one could mod an existing flashlight with a UV Emitter, but I'm looking for something ready OOTB.

Thanks a lot in advance.

 

[archimedes]

That is pretty high output for ultraviolet, what are your chief planned use(s) for this ?

Certain purposes require slightly different peak wavelengths for optimal results.

What is your budget for this item, also ?

 

[Olumin]

The exact intended use is not really important here, it will be used in a variety of situations, both outdoors and Indoors. It is important that the light is able illuminate larger parts of a medium to large sized room at once from several meters away. I also plan to use it to search for certain minerals and fossilized deposits on beaches. I suppose that means it should not be too spotty either.

Budged it about >200€.

 

[archimedes]

Yes, for rock hunting, that is one of the more "wavelength-sensitive" purposes and my (non-expert) understanding is that 365nm is not the exact optimal peak output.

 

[PhotonWrangler]

The best UV light for mineral fluorescence is going to be filtered shortwave UVC at ~254nm. A smaller subset of fluorescent minerals will glow when excited by longwave UVA at 365nm. i haven't seen any shortwave UV LED flashlights yet, probably because shortwave UV LEDs are still fairly new and low power. If you need shortwave UV you might have to settle for a fluorescent-based lamp for now. None of the fluorescent ones have much throw IMO. I'm personally looking forward to having a shortwave UV LED flashlight someday.

 

[Olumin]

That is good to know thanks. Well, since the light is supposed to be also used for a variety of other purposes, and since shortwave UV flashlights dont exist yet, lets just get back to my original question for a 365nm light. It is really intended to be a allrounder UV torch, since its my first one anyway.

 

[PhotonWrangler]

I recently purchased a Tattu brand 5w 365nm UV flashlight with included Woods glass filter. It runs on a single 18650 cell and has a built-in micro USB charging port. It has a single 365nm LED.

It is easily the brightest "black light" UVA flashlight that I own and fluoresces nearby things quite brightly. The beam is slightly ringy so I might want top get a better reflector at some point.

Out of curiosity I grabbed a 365nm dichroic "notch" filter and placed it in front of the lens. Predictably the UV output dropped significantly, which suggests to me that the LED puts out some energy at exactly 365nm and a lot of energy on either side of it, and the external dichroic filter is chopping off the sidebands. This isn't an issue for me although it tells be a little bit about the spectral content of the LED.

 

[wayben]

I've been thinking about getting an HDS with the 365nm UV option. Might be worth a look for you.
Wayne

 

[TorchBear]

I put together a 365nm P60 light with some bits from Kaidomain. They have hosts, filters, drop-ins etc. You ought to be able to make several for the budget you quoted. The Sofirn SP31 also comes in a 365nm version.

 

[Olumin]

I completely forgot about this thread. Just as an update, I ended up making a compromise in output and got a Weltool m2-bf. 365nm at around 2W and integrated visible light filter. Regulated and no PWM. The two modes are actually very useful for inspecting objects close up. Very happy with it. Can recommend it.

 

[adamlau]

You made very little to no compromise in output. Weltool is a top tier manufacturer and the M2-BF is not much different than any of the generally recommeded offerings. The current crop of UV LEDs feature high Vf and the only way to reasonably run them for extended periods of time without a drop in output is a multi-cell and/or buck/boost setup = costly (e.g. HDS UV). Else, a fully custom unit, or the Polarion NET40 a.k.a The King of UV Handhelds. I hope to own a NET40 someday...