Background of an inversion: the first gas laser

摘要

A description of the problems encountered in creating the firstncontinuously oscillating laser (the helium-neon “opticalnmaser”) is given, together with some previously unpublished datantaken by the author on the excitation transfer process between heliumnmetastables and the upper laser levels in neon. Research on thenhelium-neon excitation transfer problem is traced back to a little-knownnpaper by Headrick and Duffendack published in 1931. An interestingnhistorical coincidence is noted in that most of the people who didnpioneering work in the laser field had some connection with the PhysicsnDepartment at Columbia University. That probability arose becausenColumbia was the birthplace of induced resonance experiments in physicsnduring the 1930s