Frequency-stabilized internal-mirror Helium-Neon lasers are essential as light sources for high accuracy laser interferometry. A He-Ne laser is coher-ent for a much longer range compared to a regular laser diode, extending its range of use. For example, good long laser beam coherence allows us to keep a high frequency amplitude when we have a setup on a long table (interferometers). One issue with these lasers though is that the power and frequency of the beam tends to fluctuate due to mostly thermal instabilities that cause changes in the length of the laser tube. However, it can be automated using a micro-controller, adjust the position of the S and P polarization on the lasing output power curve in order to make them equal on opposite ends [1-3]. Once stabilized it can be used in applications such as wavelength and vibra-tional metrology, it also serves as the backbone for stabilization of interfer-ometers used for the study of coherence properties of light [4-5]
