Takeshi YASUI,1 Tsutomu ARAKI1 and Norihito SUZUKI2

1Department of Mechanical Engineering, University of Tokushima, Jousanjima, Tokushima, 770 Japan, 2Department of Precision Engineering, Osaka Electro Communication University, Neyagawa, 572 Japan

(Received August 21, 1995; Accepted April 1, 1996)

A single-mode frequency stabilized laser with modulation-free and moderate power is desired as a light source for an ultra-high resolution interferometer system and/or a rapid laser calibration system. For this purpose, we developed a new stabilized laser system that utilizes intermittent control of a 2 mW transverse Zeeman stabilized He-Ne laser (Zeeman laser) with an iodine stabilized He-Ne laser (I2 stabilized laser). Because of the intermittent control, working time of the I2 stabilized laser is reduced. The Zeeman laser has two operational modes: independent and slave mode. In the independent mode, the Zeeman laser is stabilized through control of Zeeman beat frequency. Temperature dependent drift of the oscillation frequency during the independent mode is periodically corrected by the slave operation utilizing frequency offset locking to the I2 stabilized laser. Frequency instability of the Zeeman laser in independent and slave modes is 7.7×10-11 and 2.0×10-11, respectively, at the sampling time of 100 s.

Key words: frequency stabilized laser, I2 stabilized laser, transverse Zeeman laser, frequency offset lock, unmodulated single-frequency light