UV triple using Sofirn C8F

Anyone ever measure how much the come-with front glass eats the UV content if you’re not using a ZWB filter?

Imagine it ain’t quartz, but generic Mystery Glass.

It would be about the same loss as visible light, so a few percent, say 5. The cut-off wavelength of glass is much lower than 365nm, about 300.

Up to now I only own a single UV light (S2+) and I’m still afraid of hurting my and my families eyes, read something about long term macula degeneration, bought safety glasses therefore. So I’m not sure whether it’s a good idea to use filters, since without them it’s easier to detect if the light is on.

@Scientist
I like your avatar, would also fit me pretty well … :smiley:

I am interested in building a high power C band source. My intent is sterilization (not mine).

From research it appears that there are various sources of broad band emitters in this band. For killing bacteria and fungus, this area seems to be the sweet spot. The more power the better.

It needs to be reasonably hand held. But I am looking at the idea of a “whole room” sterilization.

The impetus for this are multi-fold.

People have fungus problems in the house. This could deal with the infestation if set in an area with said fungal infection. Having a contractor in to fix it - $$$$.

This range of the spectrum also kills a wide range of really nasty bacterial material. Some are quite resistant to antibiotics. We are fairly frequently exposed to these bacteria. They are responsible for diseases that can not be cured with normal biological techniques.

A reasonably designed device could prevent a lot of otherwise near immune to everything disease propagation. I would like to make some hand sterilizer stations for the house and a directed beam for using on skin.

I do understand the issues of UV exposure to the eyes. And, long term, exposure to the skin.

I am going to start a new post on this subject. I am posting here to get attention from the people that may already looking at this.

You might then just want to get a “germicidal bulb”, basically a small fluorescent tube but without the phosphor coating.

I used to use mine to ozonate the whole room. Also helps when you get bronchitis (O3 was the only thing that could stop the incessant coughing).

There were a few articles a few months ago about the benefits of using portable 254nm lights to irradiate hospital rooms to prevent or at least reduce iatrogenic infections.

@Flashy Mike, yes I’ve set my share of things on fire.

@alternety Take a look at this open access article on using far UVC (207-222nm) for germicidal use Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases . You would think it would be more dangerous than the longer wavelengths but apparently it is absorbed so quickly in the outer skin layers it is less dangerous for humans than say 365nm. Apparently they are already building small handheld devices for places like operating rooms. Don’t think we will see it in flashlights any time soon. This article led me to a few more that really emphasize that 365nm is not good at all for humans. Between generating melanoma in your skin or cataracts in your eyes, it is something to be avoided. Fortunately I plan on using my flashlight in only short bursts with good eye protection. But being out in the sun is really bad for you unless you are covered up.

Yes, every risk assesment of UV flashlights must be set against what sun exposure does to you, to put the risk in perspective to every day risks that are out there and considered as normal. That said, these high powered 365nm lights combined with wide open eye pupils in the dark, for short periods probably gets well above the every day risk.

Scientist, I have spent the last couple of days poking for all sorts of info on C band UV. The link you gave me on the 207nm - 222nm is extremely interesting.

Aside getting extremely annoyed by the number of products that match 2xxnm on a search (frequently by just deleting it from my search parameters) but when you look the actual material runs from 400nm to the emissions of a burning match. Oddly, these offers all seem to include Chinese text.

As best as I can tell at this point, diodes in the target optimal frequencies. There are some in the upper 200s. Most are quite expensive. Some of the larger wavelengths can impact the pathogens, but lack the benefit at 207 of being stupid proof. That would make it practical to sell a device in the drug store. Big bucks there.

I saw a brief bit that talked about being able spread the spectrum of an led and stretch it across the region of interest. They were talking, I think, about some sort of a filter array that could alter the emerging light from the narrow band input. But I have no idea how that could work. And I may have gotten a completely incorrect information by not understanding.

Very nice Scientist! Thanks for sharing the great info, sweet build, and interesting site. I would love your light in the woods at night! So many interesting things can be found with my S2+uv that I never even knew about, like big millipedes fat as a pencil and two or three inches long. I think the danger of using these lights outside in a natural setting are way lower than inside, where there are more reflective surfaces. Still, it’s a good idea to be wearing glasses, especially with that awesome triple. As to not needing a bright uv light, you don’t, until you get a decent one, that is. Then it’s flashaholism as usual.

Cool :+1:

Quest for far UVC not working out well.

From further reading, 222nm appears to be the wavelength I need. I believe 207nm works, but for an unknown reason 222nm is better.

I have pretty much abandoned the search for LEDs in this range.

The only source that seems viable is from Kr-Cl gas excimer lamps using a filter. It is relatively inexpensive. Uses high voltage, which can be generated by a small power supply. But the manufacturer will not sell me one of their development kits.

Alternety I am so sorry for your ongoing health issue. Here is the problem:

Presently UVC leds have much poorer quantum efficiency (by several orders of magnitude) than the 365nm variety. This is due to the much higher number of defects in the short wavelength leds compared to the longer wavelengths. You are just a little ahead of the curve on needing the really short UVC leds. But with the rapid development of these leds I hope to see some commercially in the near future. Little comfort for someone who has an existing health issue and needs something now. You can get a KrCl light source for relatively cheap on ebay if you are lucky https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR0.TRC0.H0.Xexcilamp.TRS0&_nkw=excilamp&_sacat=0 (search for Excilamp on ebay).

There is a nice application note from Crystal IS here you might like to see that gives a table of UVC effectiveness for various bugs http://www.cisuvc.com/content/documents/files/UVCLEDsforDisinfection.AN1.pdf

You may want to have a look at swimming pool UVC desinfection technology. It uses incandescent (?) light tubes that emit 253.7 nm, made by Philips.
I have seen up to 25 W effective UVC at 75 W electric.

Thanks Scientist.

TBone - Thanks, but it has to be 222 nm.

Nice build! I wish someone sold the correct glass as round lenses, I can only find squares or 22mm diameter circles.

djozz found some on Kaidomain http://kaidomain.com/p/S027557.42mm-x-1_5mm-ZWB2-UV365nm-Ultraviolet-UV-Filter-for-365nm-UV-LED-Flashlight.

Thanks for the inspiration Scientist and the testing Djozz, I just built one of these after using S2+ UV builds for the past few years. I cant believe the difference, I use florescent dyes to find leaks in roofing and waterproofing and the throw on the C8f UV build is simply amazing. Cheers.

Good to hear of some functional use of this weird washout of the flashlight hobby.

I still have to build my C8F UV triple, maybe if I have new money I can use the newly listed (but already a few years in production) 1500+ mW LG leds from the Convoy store.

Great to hear. I like how compact it is too. I hardly notice it when I have it on my belt.

Also I did this before djozz finished his tests. He showed there is a more efficient UV emitter than the SST-10. Also there is now a C8F that uses a 21700 battery for longer lifetime. So I would probably do things differently now.