Fundación Galileo Galilei - INAF Telescopio Nazionale Galileo 28°45'14.4N 17°53'20.6W 2387.2m A.S.L.

Seminars at FGG

"Optical interferometry length metrology for high-sensitivity ring laser gyroscopes"

Speaker: Rosa Santagata (Univ. of Siena, INFN )

Date and time: 2015-06-03 12:30

The sensitivity achieved by large ring laser gyroscopes opens the perspective to observe in an Earth located laboratory extremely small effects expected from fundamental theories of physics. The next generation sensor that could provide the required accuracy is a multiaxial heterolithic ring laser, actively stabilized via a precise external diagnostic of circulating laser beams path. I'll talk about the research activities and recent progress toward the development of a large frame He-Ne triaxial sensor with an ultimate accuracy of 10−11, in order to detect the relativistic Lense-Thirring effect related to the Earth rotating mass. The name of the project is GINGER - Gyroscopes IN GEneral Relativity. The actual activity is focused on the control of the systematic errors related to the fluctuation of the square cavity geometry and the laser active medium parameters. A method based on optical interferometry has been developed for canceling the deformations of the resonator. The method is based on the measurement and stabilization of the absolute length of the cavity perimeter and of the resonators formed by the opposite cavity mirrors. The optical frequency reference in the experiment is an iodine-stabilized He-Ne laser, with a relative frequency stability of 10 -11 . The measurement of the absolute length of the two resonators has been demonstrated up to now on a test bench.

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