The HeNe laser was the first successful gas laser and the first to have a continuous output.
In 1961, a group at Bell Laboratories were able to excite Ne atoms in a low pressure gas and make them lase in the infrared part of the spectrum.
Eighteen months later they achieved operation at a wavelength of 633 nm in the red.
This laser was built by a Gold Coast firm, Laser Electronics, in the 1980s, using a tube made by Hughes, and was used at UQ in student laboratories. The tube contains a mixture of helium and neon gases at low pressure. A current passing through the gas excites both types of atom. It is the neon atoms that are stimulated to emit the red light; the helium atoms pass their energy across to the neon atoms in collisions.
Mirrors of extremely high reflectivity, above 99%, are sealed to the ends of the tube with special mounts that allow them to be aligned so the the light can bounce back and forth many times to be amplified by the atoms. A little of the light escapes from each end to form narrow, intense beams, many times brighter than the Sun.
