A PORTABLE IODINE STABILIZED HE-NE-LASER AND ITS USE IN AN ABSOLUTE GRAVIMETER

A portable, robust, and easy to use iodine-stabilized laser operating at a wavelength of 633 nm has been realized at the BIPM. The size of t he laser and its electronic servo are such that they can be installed in a suitcase having dimensions acceptable in an aircraft cabin as han d baggage. The performance of this laser is comparable to that of stat ionary lasers. A frequency repeatability of a few parts in 10(11) and a frequency stability that can reach 2 parts in 10(13) on a 300 s samp le time have been achieved. The radiation emitted by the laser can be used as a reference for optical interferometry for several years witho ut the need for periodic calibration and its life is limited by that o f the laser tube. A prototype has been installed in an absolute gravim eter and continuous sets of g measurements extending over more than th irty-hour periods have been achieved with standard deviations on the a verage value of g of about 2.5 parts in 10(8).