Measuring UVC Light Waves

https://store.uvsolutionsforhome.com/category_s/1829.htm

https://www.amazon.com/RCYAGO-Radiation-Illuminance-Luminosity-Measurement/dp/B087LRJTQB

Disclaimer: I don't have any experience with any of these.

https://hackaday.com/2020/03/27/measuring-uv-c-for-about-5/

https://hackerfarm.jp/2020/03/nukemeter/

Same disclaimer...

I want to tune a laser to the 222nm wavelength, so I need a specific wavelength readout from about 200nm to 230nm minimum, and would prefer a wider range....

https://www.ssi.shimadzu.com/products/uv-vis-spectrophotometers/faqs/instrument-design.html

Try this:

https://www.ushio.com/product/uit2400-handheld-light-meter-for-222nm/

And if you are looking for a good source of 220nm light try this:

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=11783

Found this...kind of pricey though at $2.5k

https://www.intl-lighttech.com/products/ilt2400-222uv-complete-system-measuring-222-nm-excimer-and-uv-led-light-sources

Seems easier to use than the one you found...

I am familiar with the deuterium lamps, they are not wavelength specific enough for my application, plus very expensive at $3k....but a good tool for some projects...

Thanks for your efforts guys...

I would explore a DIY spectrometer. Acquiring a diffraction grating capable of resolving UVC would probably be your biggest difficulty.

Yes, it gets difficult when you enter the non-visible UVC range...

This looks like a useful document

https://publiclab.org/system/images/photos/000/026/339/original/DSLR_spectrometer.pdf

Of course you'll need to make lots of changes to get from visible light down to UVC

Thorlabs make 1200 grooves/mm diffraction gratings for under $100

Is $1,000 affordable?,...
now that I rattled you,... $400.00 sounds better, don’t it...

it doesn’t hit the 300nm range though...

If you use a standard (non-blazed) grating you can use visible light to check the 2nd order spectrum at 444nm. If you get a peak in the 2nd order spectrum at 444 nm, then you know the 1st order peak is at 222 nm.

You can use a blue LED (typically they’re at 450 nm) and a green laser (at 532) to calibrate your 2nd order spectrum.

It turns out that the diffraction amount is very close at small angles but not exactly proportional to wavelength.

If you have a grating of line spacing, d, illuminated by collimated light of wavelength lambda (λ) and a screen parallel to the grating at distance D as shown above, the amount of deflection y/D is a function of the wavelength, λ, and grating spacing, d. It is determined by the ratio λ/d.

From the above two figures, by similar triangles:

λ/x = y/D. x=sqrt(d²-λ²). y=Dλ/sqrt(d²-λ²).

If the screen is not parallel to the grating, the angle of deflection, θ, can be calculated from d and λ.

sin(θ)=λ/d, or θ=arcsin(λ/d).

If you want to test 222nm far uvc light, choose professional uvc radimeter, but it is relavtively expensive.

“That's a great idea. (I'm thinking you meant the 1st order of 444nm should be the same as 2nd order of 222nm. Longer wavelengths diffract more.)”

Yeah, sorry. I thought that was obvious.

You (ie, Solar Eagle) don’t want a blazed grating. All (or nearly all?) blazed gratings are designed to enhance the 1st order spectrum. The 2nd order spectrum is the one to examine, and if you use a blazed grating it will be faint.

An aluminum (or aluminized) reflection grating would be good - if you can find one - since aluminum has good reflectance in the UV. Most common glasses attenuate UV somewhat, but if the glass is thin, which it usually is for gratings, the attenuation won’t be too bad.

Cheap gratings are available on polyester film. Again, these are very thin so the attenuation might be minimal.

Hello,

All the devices that I ever handled would run to tens of thousands each and would be sensitive to movement.

Maybe if it's a "one off" calibrate/set process, you could rent instrument, or hire time in a NIST lab for optics and photometrics.

The lab I ran used the peaks in Fluoro to validate our instruments at the UV end and a red laser for the high end, then verified the various peaks for linearity checking.

Thinking about it a little more while taking a walk, what if you combined the unknown UV source with the (filtered) 220nm peak from the fluorescent lamp.

You should get a "beat" frequency relative to the wavelength difference from the 220nm reference. The beat would be relative to the additive signal strength of both sources giving a higher magnitude signal to measure/detect and in a different part of the spectrum where "normal" instrumentation is available.

How about a 220 nm laser made using the same technique as the powerful green lasers made by frequency doubling infrared?

https://www.photonics.com/Articles/Compact_UVC_Laser_Shows_Promise_for_Biomedical/a61611

This would be perfect if it had more power....it is very weak, and I'm guessing expensive...The question is can it be scaled up....?

You ever heard of a whispering gallery resonator...?

https://detroit.cbslocal.com/2011/11/29/a-smarter-way-to-make-ultraviolet-light-beams/

Do you know if bandpass filter can change the wavelength?

How difficult would it be to Heterodyne two different wave lengths to get the desired output wavelength?