Helium-Neon  gas lasers were the first lasers mass-produced. They were used in everything from UPC scanners to video disc players and laser printers.

Although they have been largely replaced by other lasers, helium lasers still offer superior beam quality. A helium laser has a gassy  smell and long laser length. These beam characteristics are good for many laser applications including infrared and holography. Infrared is when you see body heat.