Content Warning: The following is possibly very boring to approx. 90% of suspected reader base. Probably higher.
Have you heard of a lock-in amplifier? It's one that is connected to both an input signal that is being supplied in intervals at some frequency and the output signal so that it "knows" to amplify just the signal you're after, being referenced to the proper frequency and phase. I remembered the professor in my circuits class last semester describing that set-up as a good way to pick up your signal and cut down noise. I pictured the front end being electronically turned on and off really quickly. When your input signal is a laser beam, though, there is a simpler way--you can use a chopper. What's a chopper? It looks like a fan, or one of those annoying wheels at miniature golf courses, and sits spinning in front of the laser-- blocking the beam, letting it through, blocking the beam, letting it through, at the required frequency. People are so clever!
My research supervisor explained somewhat apologetically that the set-up for each run of photoluminescence analyses will take a long time since everyone moves all the pieces around for their different experiments. I don't think he realized that lining up laser beams with mirrors and lenses, funneling liquid nitrogen into mini dewars, and setting parameters on equipment that actually use tricky principles I'd thus far only seen on physics exam papers isn't exactly a drag.
In case anyone was annoyed by the rambling about what I find interesting at the research lab without a more formal description on the project/task (unlikely, but hey), the plan is to characterize various samples of III-V quantum dots (grown by someone else in the group) to see how different growth methods affect their physical and optical properties (hence the AFM and PL trainings). They're shooting for a specific band gap/emission wavelength. Wikipedia can tell you more accurately and succintly about quantum dots than I could if you're interested, but apparently they've been around since the 80's. Who knew?
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