Abstract
Frequency stability and resettability of two stabilized 633nm He-Ne lasers are measured. The lasers are trial manufactures by a domestic production company. The laser is set in transverse magnetic field and generates intramode beat, the frequency of which is used for stabilizing the laser by thermal control. It has a quartz oscillator as a frequency standard. An iodine stabilized 633nm He-Ne laser is used as an sbsolute standard of optical frequencies. Beat frequency between the standard and test lasers are measured by a frequency counter. Each of the two test lasers shows frequency fluctuation of 1MHz peak to peak and frequency stability is estimated to be 2×10-9 for 6 to 8hrs measurements. For one of them the frequency monotonically decreased up to 35MHz during repeated mesurements for 3 months. The two test lasers showed a frequency difference of about 70MHz each other.
