I spent the better part of an hour putting nail polish on mirror mounts yesterday.
No, this isn’t a tragic misinterpretation of my students’ advice to “wear more pink.” It’s because the optical table looks like this:
All those black things are mirror mounts like the one in the top picture, holding mirrors that are precisely positioned as part of one beam line or another. There are at least four different important paths in the picture above, and they tend to bend around a lot, and cross each other. Here’s the same picture with the beam lines roughly sketched in:
There’s one laser under the cardboard box at the bottom of the picture, and a second in the grey box at top. The dark purple beam is from the upper laser, and goes through an acousto-optic modeulator to shift its frequency, and then off to some laser diagnostics and locking stuff (the light blue stuff at upper right is part of that line). The bright pink beam at top goes to an optical fiber (the yellow wire-like thing running off the table to the left), and gets fed into the orange beam line, where it serves to “injection lock” the higher-power laser under the cardboard box. The bright red line is from the high-power laser, and heads over to the main experiment.
The main experimental chamber is on another table, with a similar array of optics on it, and a similarly tangled set of optical paths. Relative to a lot of labs, this is an uncluttered table, but if you don’t know what you’re looking at, it can be a little daunting to try to figure out what’s going on. One of my thesis students is about to shift over to working on this apparatus, from working on a different experiment, and I need him to be able to figure out the layout as quickly as possible.
Hence the nail polish. The mounts are black anodized aluminum, which means that ink doesn’t show up very well, and colored tape doesn’t stick very well. Enamel nail polish does stick, though, and shows up very clearly against the black mounts (you can see small spots of it on the mirror mounts in the top picture).
I asked Kate to get me a selection of colors, and she came through in a big way, thanks to the garish colors in the teeny-bopper section of the local CVS. Seven different colors (though the white and blue aren’t that easy to tell apart) provide plenty of options for identifying mirrors associated with different beam lines. I put a small dot on the top of each mount, which makes it easy to identify the different paths, or at least, the mirrors associated with the different paths.
(I wish I could say that this was an original idea, but my undergraduate thesis advisor used little dots of nail polish to distinguish between mirror mounts that belongs to his lab, and mounts stolen on loan from the teaching labs. I’m just using more colors than he did…)
Hopefully, this will make it a little easier for my current and future students to figure out what’s going on. If not, well, I can always donate the rest to first-year students with no fashion sense…