English: A homemade laser pistol that shoots a laser beam, constructed by Stanford University physics professor K. H. Sherwin in 1964, four years after the laser was invented, to demonstrate to his classes how lasers work. The body (left), recycled from a toy raygun, holds a pencil size ruby rod and two flashtubes.(right). It is attached by wire to a 200 watt-second high voltage power supply. When the trigger is pulled, the flashtubes go off, creating a pulse of red laser light from the rod. The coherent light pulse is powerful enough to pop a blue balloon (shown at left); but not a red one, since it reflects the red light.
Alterations to image: cleaned up some dark areas around the circuit board on the left that looked to be artifacts from the page scan.
This 1964 issue of Popular Science magazine would have the copyright renewed in 1992. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1978 and later show no renewal entries for Popular Science. Therefore the copyright was not renewed and it is in the public domain.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.