Aligning a sequence of amplifiers and mirrors with hair-thin precision on a tabletop anchored to a steel block deep underground, scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have produced a powerful green laser. The light—the highest average power green laser ever generated by a single fiber-based laser—will be crucial to experiments in nuclear physics at the Lab’s Relativistic Heavy Ion Collider (RHIC).