Experimental study on frequency stabilization method of internal-mirror He-Ne laser

Frequency of an internal-mirror He-Ne laser is stabilized by using a micro cooling fan, instead of traditional heating method. Both the relationship between driving voltage and rotating speed and the thermal expansion of the intermal-mirror laser are discussed. The cavity length of the laser is controlled and adjusted by air cooling. The frequency stabilization is based on a theory of power balance between two longitudinal modes. The average temperature of the laser tube is less than 50 ℃ when the frequency is stabilized. A frequency fluctuation of less than 1.4 MHz in 20 h and a frequency relative standard uncertainty of U=4.710-9 in 4 months are evaluated by measuring the beat signal with a high-precision laser stabilized by iodine.