265nm lasers for SARS-CoV-2

[LaserMicroscope]

So for sterilizing wide areas we need a more efficient source of UVC. What about filtering the raw output of HID bulbs? I know that if the outer bulb of a metal halide or HPS lamp gets broken the raw output from the inner capsule is pretty profoundly dangerous due to the high levels of UV. But is there enough UVC of the appropriate wavelength to make this even close to practical, if there was an appropriate filter to block the wavelengths that would otherwise cook our eyes and skin? Could the mix of metals in a metal halide lamp be tweaked to maximize the output of the useful wavelengths?

Well not for sterilizing coronavirus, but yeah you’re on the right track here. HID lamps actually create an arc between tungsten electrodes, creating a plasma in the noble gas environment that is deliberately spiked with metals. The plasma itself can emit UV, but most HID lamps have metals present too because their plasmas have lots more emission lines (d block metals blah blah unoccupied orbitals blah ) In the case of mercury vapor, there is a prominent deep UV emission, hence many germicidal lamps are, in fact, mercury vapor style HID lamps with their UV shielding removed! Unfortunately tweaking to protect eyes and skin is hard - the mechanism that makes UV sterilization work is the exact same that causes sunburn: DNA damage.

-Edit- I see in your post you mentioned about the metals in the lamp so my explaining it was probably unnecessary, sorry! Not trying to be pedantic, just on a phone and have to go from memory of what I read in your post. Be that as it may, yes I bet metal mixtures can be tweaked.

 

[LaserMicroscope]

Well not for sterilizing coronavirus, but yeah you’re on the right track here. HID lamps actually create an arc between tungsten electrodes, creating a plasma in the noble gas environment that is deliberately spiked with metals. The plasma itself can emit UV, but most HID lamps have metals present too because their plasmas have lots more emission lines (d block metals blah blah unoccupied orbitals blah ) In the case of mercury vapor, there is a prominent deep UV emission, hence many germicidal lamps are, in fact, mercury vapor style HID lamps with their UV shielding removed! Unfortunately tweaking to protect eyes and skin is hard - the mechanism that makes UV sterilization work is the exact same that causes sunburn: DNA damage.

-Edit- I see in your post you mentioned about the metals in the lamp so my explaining it was probably unnecessary, sorry! Not trying to be pedantic, just on a phone and have to go from memory of what I read in your post. Be that as it may, yes I bet metal mixtures can be tweaked.

Replying to myself - based on sanitation guidelines, you’re going to kill at least 90% of bacteria if you hit a particular square centimeter of material with 8mw of 270nm light for 1 second. For giggles and because this is LPF, let’s say we want to get 12mw per cm^2. With a laser beam this kind of power density is easy, but it gets harder for larger spot sizes. Think how big a flashlight beam gets over just a few feet. In 5 seconds of google research, I found a UV LED bulb that claims to draw 60W of power. Problem is, these UV LEDs are hilariously inefficient, you’d be lucky to get 5% power conversion to light. SO, with an LED based approach, every W of power in only gets you at most 50mw out, enough to cover about a 2x2cm area with sterilizing light. The 60w bulb I found would cover around 16x16cm, but that’s a pretty small beam from any real distance. The key here is figuring out how to get more power out.

-Edit- And yes, my brain went back to lasers too. With optics, we could totally expand a laser array to a nice power dense beam. Totally true. But now the issue is cost. There aren’t direct diode shortwave UV lasers I can find, necessitating optical trickery to get there. That gets expensive FAST. It would be much more economical to create more light power by a different technique.

 

[WizardG]

What wavelength is that 60W part?

 

[LaserMicroscope]

What wavelength is that 60W part?

They claim 253.7, so not ideal but functional. I can’t speak for the validity of that manufacturer, I literally googled “UV led array” to get some kind of clue what was available. If I was seriously considering this project I’d be wondering - could I mobilize a 60W 100+V power supply? Is this form factor (light bulb) the best? I’m not an LED guy but I have a feeling some form of custom implementation from parts could be way better

 

[kecked]

Good explanations thank you. It would be far more effective to wipe down the surface with soap and water or alcohol. I favor soap and water because it’s safer cheaper and more available. People think this is over in two months. Think two years....

 

[trussmonkey25]

Good idea... but I wouldn't use a drone fitted with Lasers that
emit UVC radiation due to the risk of human health.
I've recently purchased UVC LED lights to disinfect incoming
mail and courier packages in a dedicated box with a turntable.
Hopefully this will kill any virus that could still be viable on
any packages.

Jerry

Can you make somthing to scroll cash through, for example when ever you pay a cashier or teller, you slide cash into this device instead of handing it to her

 

[Seoul_lasers]

Had no idea UVC could be had from AlGaN LEDs... wow.... and they are quite expensive too $60ea.
Pics?

 

[kecked]

You could not even find them a few months back

 

[steve001]

Soap and water are as effective at denaturing this virus as anything else is. The viral coat is lipid based, so any soap or detergent will destroy it. Use cold water when you wash as that will help with keeping your skin hydrated. I use Dial soap.

 

[steve001]

Here's the practical solution. It's a UVC light emitting autonomous robot. Watch the video.

Autonomous Robots Are Helping Kill Coronavirus in Hospitals

Robots that can efficiently disinfect hospitals using UV light could slow coronavirus infections

spectrum.ieee.org

 

[Cyparagon]

60 watts worth of UVC LEDs? For less than 5 figures? I call bullshit.

Putting a frequency quadrupled YAG on a drone is an abjectly stupid way to protect yourself from disease. Just drop it until you learn more than buzz words.

UVC itself is good for disinfecting, but the room cannot be occupied during, and a bit after treatment. Shadows are also havens. This also means it cannot penetrate porous surfaces. The only tech I'm aware of that produces efficient UVC for a reasonable price is a low pressure mercury lamp with a quartz sleeve. A 36W lamp is maybe $20 and runs off a regular fluorescent ballast. I have a few myself. They give a spooky blue glow, but don't be fooled. most of the light emitted is UV.

No, you can't use HID lamps. I've tried. Removing the outer glass envelope also removed the insulating environment for the arc tube, so the arc tube doesn't get hot enough to operate properly. You'll get some UV out, but it's very inefficient, and the arc tube will degrade quickly when exposed to the environment.

Just stay away from people, don't touch things, and wash your hands. There's really no need for most of this extra tech nonsense. Playing with an ionizing radiation source is almost invariably going to cause more harm than good.

 

[Alaskan]

Hhhhha, I've been looking for 50 milliwatt UVC LED's, good luck, I'm not finding them. Gotta go to glass for that, but florescent UVC lamps are cheap, they are just mercury florescent bulbs without the phosphor coating inside.

 

[Eddie H]

Sorry for my absence, I've had some personal issues to deal with but I'm back again now! I stumbled on this youtube video of just such a drone!

 

[Teej]

Just noting that as far as efficiency, really, a florescent tube UV source works better than LEDs, and so forth.