Keiichi TANAKA,¹ Junichi KOSHIGOE,¹ Yosio NAKAJIMA,¹ Yong Chol LEE² and Osamu TAKANO²

¹Department of Applied Electronic Engineering, Tokyo Denki University, Hatoyama, Saitama, 350-03 Japan, ²NEO ARK Corporation., 2062-21, Nakano, Hachiohji, Tokyo, 192 Japan

(Received June 26, 1996; Accepted September 3, 1996)

Spectral quality and reliability of four kinds of ¹²⁷I₂ cells for an wavelengtn standard were investigated. A 20 year old 10 cm long sealed off iodine cell has shown its long life and had sufficient absorption characteristics comparable to the newly made three cells in regard to spectral line width and signal-to-noise ratio of the absorption signal. A dispersion of absolute frequencies of the three cells including the 20 year old cell is in a range of 35 kHz, which is equivalent to a frequency reproducibility of 7.4×10^-11. A compact iodine stabilized 633 nm He-Ne laser with a 23 cm long resonator and 4 cm iodine cell has been developed. Its frequency stability has been estimated to be 9×10^-13 by the Allan deviation at integration time of 4000 s. The laser supplies 14 wavelength standards being locked at iodine absorption lines from a to n.

Key words : wavelength standard, He-Ne laser, iodine cell, pressure broadening, frequency shift, frequency stability, Allan deviation