| We describe a simple cost-effective frequency stabilization technique of a Helium-Neon gas laser. A detection circuit compares light intensities of two orthogonally polarized transverse modes of the laser. These modes are symmetrized about the Doppler broadened emission line of neon at the 3S 2 to 2P4 transition. By keeping the ratio of the two light intensities constant, a feedback mechanism adjusts the length of the cavity by electronically activating a heating element attached to the laser discharge tube. Thus, by holding the intensities of the two modes constant the optical length of the cavity is stabilized obtaining the required frequency stabilization of the Helium-Neon laser. |
