Also camera sensors. AFAIK most (all?) high speed sensors are actively cooled with TEC. All high sensitivity cameras are, most telescopes and satellite cameras also i think

Yea, plenty of cameras need precise temperature control too. A laser or LED shifting spectra is just the easiest and most accessible example I could think of.

Highspeed needing it is a head scratcher though. Best I can come up with is the sensor needs relatively low temperatures, that or as the frame gets smaller on the sensor to up the framerate the power density goes nuts.

Also sensors with long exposure times, which are cooled to reduce the dark current. Amateur telescope camera chips are often actively cooled for long exposures.

interesting to know that there are actual critical applications for this technology though it does have limitations as I think the JWST is cooled with some sort of exotic compressor useing liquid helium, though perhaps a solid state device is part of the stack as they are after a very low, very stable temperature