(The following photo provided courtesy of: Daniel Ames (dlames2@aol.com).)
(The following photo provided courtesy of: Thomas Galeski (azotic@aol.com).)
There is more information on HeCd lasers in Sam's Laser FAQ in the chapter: Helium-Cadmium Lasers.
The Omni-100 is a very popular power supply which can drive a variety of Omnichrome HeCd laser heads including those that look similar to the model 326, above.
(The following photos provided courtesy of: LesioQ (Piotr.Kucharski@stream.pl).)