It's been a while since I've posted an old laser, so here goes. This one is a 1983 Advanced Kinetics model NIRL "XeHe" Helium-Xenon flowing gas laser head. It gave about 100 mW at 2-4 microns wavelength, and featured a water cooled tube with water cooled electrodes, and piezoelectric wavelength tuning. The cover has windows installed, so I think this one went to a trade show at some point. I love the gold plated Brewster window mounts.