UVC or "deep UV" flashlights?

S

sidpost

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I have the Fenix dual LED "pen" UV light and UVA Olight's in the I5 and I3 flavors. I should note I'm not trying to sterilize water or surfaces from COVID.

What are my better options for UVC? I'm thinking more of something in the 254nm range for minerals and similar things. $200 lights are not an option and I'm hoping to find something in the sub-$100 range.

TIA,
Sid
 
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kelmo

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Welcome to CPF sidpost!

UVC in the 254nm wavelength is what germicidal systems use if that helps. Not sure about what you would use on minerals for.

kelmo
 
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sidpost

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365nm doesn't work well on all minerals though, for general uses it covers the bases well. I'm looking for something to compliment that wavelength and have been told the 254nm is really good for minerals though, most people especially today are obsessed with it because of COVID. I'd like to find one in a AA, 18650, or 21700 flashlight to go with my other UV flashlight options.

My little AAA Olight UV flashlight is fun for scanning little orange, green and blue dots on my arm after washing up! I wonder if a new 254nm light would look different from the Olight?

Hmmm, I might need to pick a few extra AAA Olight UV's for the nieces and nephews to play with.
:party:
 
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kzb

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Apparently most "UVC" LEDs are fake. They are more likely UVA.

UVC LEDs are inefficient, and in fact the old fluorescent tubes are more energy-efficient than a UVC LED.

True UVC LEDs do exist, but they are expensive. A true UVC LED would degrade its own plastic housing and glue, so if it is in that kind of support it is fake.

UVC does not occur naturally at the surface of the Earth, and is dangerous.
 
PhotonWrangler

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I just picked up a Feit brand "UV Protect" disinfection wand for $55. This unit contains 6 UVC LEDs and 2 visible blue LEDs (to indicate to the user when it's running). I've confirmed that the UVC LEDs are the real thing. I put a couple of pieces of black tape over the visible blue LEDs and tested it. I think this is going to work out well as a relatively affordable light for fluorescent mineral hunting. The runtime on a full charge is only around 20 minutes but that's enough for my purposes. The UVC LEDs put out a very faint visible purple glow, actually dim enough that it doesn't need an external Woods Glass filter when used for fluorescing things.

I found it at the DIY store that rhymes with Bernard's. Other outlets are carrying it also for around $80. Feit's item # is UVC/WAND/6W/LED.
 
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sidpost

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I just picked up a Feit brand "UV Protect" disinfection wand for $55. This unit contains 6 UVC LEDs and 2 visible blue LEDs (to indicate to the user when it's running). I've confirmed that the UVC LEDs are the real thing. I put a couple of pieces of black tape over the visible blue LEDs and tested it. I think this is going to work out well as a relatively affordable light for fluorescent mineral hunting. The runtime on a full charge is only around 20 minutes but that's enough for my purposes. The UVC LEDs put out a very faint visible purple glow, actually dim enough that it doesn't need an external Woods Glass filter when used for fluorescing things.

I found it at the DIY store that rhymes with Bernard's. Other outlets are carrying it also for around $80. Feit's item # is UVC/WAND/6W/LED.

Thanks! That's really interesting.
 
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kzb

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I just picked up a Feit brand "UV Protect" disinfection wand for $55. This unit contains 6 UVC LEDs and 2 visible blue LEDs (to indicate to the user when it's running). I've confirmed that the UVC LEDs are the real thing. I put a couple of pieces of black tape over the visible blue LEDs and tested it. I think this is going to work out well as a relatively affordable light for fluorescent mineral hunting. The runtime on a full charge is only around 20 minutes but that's enough for my purposes. The UVC LEDs put out a very faint visible purple glow, actually dim enough that it doesn't need an external Woods Glass filter when used for fluorescing things.

I found it at the DIY store that rhymes with Bernard's. Other outlets are carrying it also for around $80. Feit's item # is UVC/WAND/6W/LED.

How have you tested it to confirm the lamps are actually UVC and not longer-wavelength UV?

Also, are you protecting yourself from the UVC (assuming it is genuine)? You could be damaging your eyes and skin.
 
PhotonWrangler

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How have you tested it to confirm the lamps are actually UVC and not longer-wavelength UV?

Also, are you protecting yourself from the UVC (assuming it is genuine)? You could be damaging your eyes and skin.


Both excellent questions!

1) I have a UVC detector card. This is a little plastic card that has an area coated with a phosphor that only glows under UVC light. I've confirmed this with known UVA and UVC sources.

2) I've been working with UVA and UVC for decades so I know to avoid exposure, particularly to UVC. Fortunately UVC doesn't pass through eyeglasses (also confirmed with my detector card). For that matter, UVA is severly attenuated by my glasses also.
 
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kzb

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Both excellent questions!

1) I have a UVC detector card. This is a little plastic card that has an area coated with a phosphor that only glows under UVC light. I've confirmed this with known UVA and UVC sources.

2) I've been working with UVA and UVC for decades so I know to avoid exposure, particularly to UVC. Fortunately UVC doesn't pass through eyeglasses (also confirmed with my detector card). For that matter, UVA is severly attenuated by my glasses also.

OK you sound like an expert !

However I think it'd be good to point out the hazards and what safety precautions are needed on an open forum such as this.

I wouldn't want one of these in the house if I had kids who might play about with it when I'm not there.
 
PhotonWrangler

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OK you sound like an expert !

However I think it'd be good to point out the hazards and what safety precautions are needed on an open forum such as this.

I wouldn't want one of these in the house if I had kids who might play about with it when I'm not there.


Thank you kzb, this is a valid point. The dangers of UVC exposure including damage to the outer layers of skin (it doesn't penetrate deeply) and photokeratitis. In both cases the damage doesn't show up right away so it might not be immediately apparent that injury is occurring, so there is no natural avoidance reaction on the victim's part. These lamps should never be left in the hands of unsupervised children for this reason.

A long time ago they used to include UVC lamps in electric hand dryers to kill germs while drying your hands, but they removed them when it became apparent that the technicians who serviced those dryers were experiencing eye trouble from the UVC exposure.

Back then those lamps were called "ozone bulbs" because they produced two different UVC wavelengths, one of them responsible for the ozone creation. Later they tweaked the formulation of the glass envelope to allow the 254nm germicidal wavelength to pass through while blocking the shorter ozone-producing wavelength. Virtually all modern UVC fluorescent lamps use this formulation for the glass envelope as ozone is a ground-level pollutant which can harm lung tissue.

Oh, and that UVC LED wand I bought? It includes a tilt switch so it only operates while facing downwards. It turns off automatically if you rotate it towards your face.
 
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sidpost

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OK you sound like an expert !

However I think it'd be good to point out the hazards and what safety precautions are needed on an open forum such as this.

I wouldn't want one of these in the house if I had kids who might play about with it when I'm not there.

I hear ya'! ;)

Personally, I'm a lot more concerned with high power lasers (i.e. laser pointers). In fact, more so than firearms! Most people show firearms respect but, not lasers.

Most UVA and UVC sources we are talking about are not strong enough to be serious concerns with reasonable clothing options and other basic protections though voicing them is good in a forum like this IMHO because you never know who will come along and read it, possibly out of context.
 
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wweiss

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This thread is great - thanks to PW and all for the excellent data!
 
PhotonWrangler

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A few years ago a nightclub thought it would be a good idea to install UVC germicidal fluorescent lamps in some of the light fixtures because the eerie defocused glow from these lamps looked "cool." They didn't know that they were exposing their staff and patrons to UVC for an extended period of time! As you would expect, many of them developed eye and skin issues the next day. This story is just astonishingly dumb and reckless and clearly demonstrates the hazards of UVC exposure. BTW that "G" in the lamp's model number designates "germicidal."
 
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yellow

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Wondering ..
the original idea was to light up flourescent "things"?
Would they not also light up with the most cheapo UV light inserts?
I mean ... i have an UV ring inside my A2, as well as a cheapo p60 UV insert in one of the 18650 hosts.
When i tote them around, the same items do "shine up"
(OK, + anything white + its visible beam, with the cheapo)
.
Could this work the same purpose without the hassles/"danger"?
 
PhotonWrangler

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Yes, UVA "black light" is far better for fluorescing most things for entertainment, leak tracing or other purposes. However there is an exception when it comes to fluorescent minerals, Many fluorescent rocks won't do anything under regular UVA but spring to life in vibrant colors under UVC,

When I was growing up I found some plain old rocks in our driveway that not only glowed bluish white under UVC, they continued to glow (phosphoresced) after the light was turned off. It sort of looked like calcite but I never confirmed what it was.
 
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Dave_H

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Not an expert on glass but I know that quartz glass is used for "short-wave" UVtubes (2537A) passing light out, and glass windows on the old UV EPROMs letting light in. It's more expensive and harder to work than "regular" optical glass for visible light. Not sure which types of glass work for "long-wave" 3660A and above.

Angstrom unit reference is historical, I imagine just about everyone uses nanometers these days, myself usually.

In absence of UVC detect device I suppose one could find an object which only lights up under UVC, perhaps a mineral sample...may not be convenient to carry in a pocket!

Happy to report that my $7 HD 3AAA UVA flashlight has not detected any scorpions so far; not that we expect them this far north, but it's good to know!

Some bulk mineral samples brought home from old mines decades ago are still outside as landscaping stones so I'll check some night with my old UVS-11 (UVC) on an extension cord, and the flashlight.

Dave
 
PhotonWrangler

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Let us know what you find on those stones under your UVC light!

As far as finding a relatively small and common UVC detection material, some postage stamps used to contain a phosphor coating that only glowed under UVC. This was used in combination with a photodetector in the sorting machines to identify which type of stamp it was as well as detecting counterfeits. I don't know if they still use this system in modern stamps. If I recall correctly, back in the day the "air mail" stamps had a phosphor that glowed under UVC with a very bright and brief phosphorescent afterglow. I believe the machine detected that flash of afterglow. I could see the flash if I closed my eyes while the lamp was on and opened them at the same instant that I turned it off. It was so brief that it took some practice to catch it.
 
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Dave_H

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Let us know what you find on those stones under your UVC light! As far as finding a relatively small and common UVC detection material, some postage stamps used to contain a phosphor coating that only glowed under UVC. This was used in combination with a photodetector in the sorting machines to identify which type of stamp it was as well as detecting counterfeits. I don't know if they still use this system in modern stamps. If I recall correctly, back in the day the "air mail" stamps had a phosphor that glowed under UVC with a very bright and brief phosphorescent afterglow. I believe the machine detected that flash of afterglow. I could see the flash if I closed my eyes while the lamp was on and opened them at the same instant that I turned it off. It was so brief that it took some practice to catch it.

Interesting P'W...I checked regular Canadian stick-on letter stamps (still use some), and the border fluoresces yellow under short-wave UV only. This reveals a row of tiny symbols which are probably scanned for value and validity. I imagine it could also detect if a valid stamp is re-used. No after-glow visible that I can detect though.

Some letters were stamped with orange bar-code at the bottom which lights up with short and long UV, but not recently. Also, some envelope postage markings (from postage machines) also light up orange under short and long.

Dave
 

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