Holography's an enormously important technique for research and industry, and it's made possible by our friend the laser. I thought I'd take this opportunity to show the lasers that brought Gabor's great invention to fruition. The first is the 1962 Perkin Elmer / Spectra-Physics Model 110 He-Ne. It was the first commercially available laser with a visible CW beam. Leith & Upatnieks borrowed one of these to do their experiments with two dimensional transparencies late in '62. This one is missing its cylindrical end covers and boots, but it has the in-line start button and current control (not shown).
The laser below is the Perkin Elmer / Spectra-Physics Model 111 He-Ne. This is a longer version of the plasma tube above, giving 10mW single mode instead of 3mW. Leith & Upatnieks bought one of these for their own use early in 1963, and eventually made holograms of diffuse 3-D objects in December of that year. Both of these lasers were RF excited. They also have large bores and Brewster windows (which look like puppy feet!).
Happy birthday Dennis!