Application of selective rotatable mirrors in a single-mode He-Ne laser with 100 mW output power

An investigation was made of the output power of a helium-neon laser (λ = 0.63μ,) with a resonator containing four standard gas-discharge tubes (two of these were taken from LG-38 lasers and two from LG-75). A system of selective rotatable mirrors, oriented at 45° with respect to the discharge axis, made it possible to halve the size of the laser and to suppress the competing emission at λ = 3.39 μ, so that the single-mode output power at λ = 0.63 μ exceeded 100 mW.