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Zenst

This is good, the usage for UV is huge and anything that reduces costs will only help.

Whilst many don't need it, I'm sure having a UV filter of your water would not go amiss.

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> I'm sure having a UV filter of your water would not go amiss

You don't need lased light for that (and using a low efficiency, high cost device also not ideal?!).

UV LEDs seem to be in development. The problem with UV fluorescent tubes is that they have horrible cycle life.

I guess everyone means UVC here. A UVA flashlight is cheaper than lunch ;) edit: my facts were scrambled. C is the nasty one... maybe my favorite (unsafe) language will help me remember that from now on.

Or maybe for photolithography hobbyist.

Yeah, especially because that hinges on having coherent light, whereas sterilization does not AFAIK.

As for incoherent UV light, I wonder how this laser compares in efficiency to arc lamps. Is that still how incoherent UV is generated? Deuterium and mercury vapor? Or have LEDs taken over?

A solution that does not use mercury, then that will make for cheaper and equally safer production and dispose.

DUV for lithography is usually produced with excimer lasers at 248 or 193 nm. While they are technically lasers, they are barely coherent and have horrible beam quality.

For other applications such as sterilization or curing adhesives, mercury vapor lamps and LEDs are popular.

Is photolithography at home limited by laser'd wavelength?

> I'm sure having a UV filter of your water would not go amiss.

UV "filter"? I thought the UV thing in water treatment was merely to kill most (if not all) of what micro-life would otherwise still live in yr water.

Filters are needed to actually get some (dissolved) solids --possibly UV-zapped micro org corpses-- out of yr water.

Most places add chlorine/chloramine to the tap water to prevent micro orgs becoming so prevalent "at the faucet" that you can get "cannot go to work tomorrow" sick.

Yes, if you live in an area with municipal water treatment, but if you rely on a private well, accessible and inexpensive UV treatment would be great. Of course, you also (generally) need a water softener and perhaps more expensive filtering equipment depending on the what metals and minerals might be present.

Why would one need a UV if there's also going to me actual filters after that? (honest question) Only thing I can think of is to prevent contamination of the filters.

Because if you have an actual filter that is a small enough micron to capture pathogens, it's also going to capture all of the really fine sediment and plug up quickly.

That why most water filter systems have "stages", every stage "covers" for the next.

It is entirely site specific. I don't have any filters, just a water conditioner (since I don't want to deal with a softener). Adding UV would probably be unnecessary but would provide some nice peace of mind.

Even more, they are getting pretty close to x-ray now which begins at 10nm.

The laser structure was grown on the (0001) face of a single-crystal aluminum nitride substrate. The measured lasing wavelength was 271.8 nm with a pulsed duration of 50 ns and a repetition frequency of 2 kHz.

I know this is a pipe-dream, but a 2.5Å x-ray laser would be a scientific revolution for protein crystallography. Instead of ~2-10(!) years to find the structure of a protein, we’d be limited by the chemistry.

Handheld UV water purifiers are already common. A lot of backpackers use them. I'm not sure how they work. Presumably they're not using LEDs.

They use mercury lamps. I took one apart to use the lamp as a wavelength standard. Don't try that at home, the sterilizers have interlocks to prevent accidental eye and skin exposure.

I have been considering doing this too. Do you have any specific advice, you would have loved to give your prior self?

Yes. Don't do it. Buy the nice little mercury-argon lamp from Ocean Optics.

First of all, the mercury lamp is dangerous, for real. Second, the newer sterilizer pens contain complicated interlock circuitry, making it impossible to figure out how to actually get the lamp to turn on by itself. I got one lamp to light up from an external power supply, then set it aside and bought a few of the Ocean Optics boxes.

As a wavelength standard, it was also a poor configuration -- most of the light can't be directed where you need it, whereas the Ocean Optics produces a nice compact beam and has a fiber optic connector.

thank you very much for the swift reply,

I actually don't need it as a wavelength standard, but as a small source for entangled photons.

I'm well aware of the dangers of deep UV and ozone (and of mercury if I would accidentally break the lamp by opening the sterilizer pen).

I'm unable to identify what Ocean Optics box you are referring to?

If I do have resort to the sterilizer pens, any advice regarding opening up and analyzing the interlock circuitry? I have an oscilloscope...

Aha, the company name changed. But I've bought these under the Ocean Optics brand, and they've always worked fine. Note that they have a variety of elements, not just mercury. If you don't need great gobs of photons, a small neon lamp is a lot more friendly to play with, still involves dangerous high voltage, but no UV. The NE-2 lamp is a common one, available from electronic parts suppliers.

I found the circuit of the sterilizer pen to be impenetrable, as it contains a microcontroller, which is a "black box" to me. I think they wanted to make it hard to jimmy.

https://www.oceaninsight.com/products/light-sources/calibrat...

Understand that I have to be conservative about this stuff. I'm not an engineer, so I have to assume the worst about the hazards.

Also, I do know from using any of these lamps, that a timer is a good investment, so you don't burn them out prematurely.

Bit of a tangent, but do the blue LEDs that hand driers often have now do anything? Or is it just marketing buzz?

DUV LEDs have existed for quite a while and produce a lot more power.

UVB/UVC LEDs barely touch 2% efficiency converting energy into photons. When they can hit 30%, I'll have the perfect mineral hunting lamp designed and built.

Would be very useful for vitiligo treatment.

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