February 18, 2026

Calibration sources for your spectrometer

A plain old white fluorescent tube works well. You get a mix of mercury lines and lines from rare earth phosphors that line the tube.

Germicidal bulb

Using one of these gets rid of the rare earth lines, but also exposes you to lots of dangerous UV light unless you take precautions. I happen to have two of these set up on only EPROM erasers.
Here is the spectrum I get:

The above uncalibrated spectrum starts somewhere around 380 nm. There are plenty of lines below that (these are the UV lines the bulb is used to obtain).

Note that there are low, medium, and high pressure mercury lamps.

Notes from Storm, 4-2026

Storm was enthused about the idea of just having Hg lines and not having to be aware of and ignore all the lines contributed by rare-earth phosphors. He found an inexpensive EPROM eraser on Amazon and built a calibration source.
Feedback? Questions? Drop me a line!

Tom's Mineralogy Info / tom@mmto.org