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.
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.
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...
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.