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Physics Seminar - Progress in high resolution Sagnac Interferometry

This is a past event.

Friday, October 9, 2020 at 1:00pm to 2:15pm

Virtual Event

With Prof. Ulli Schreiber, Technische Universität München.

Join us on Zoom

Strap-Down inertial sensing laser gyroscopes are essential for the attitude control of aircrafts - they keep helicopters and planes in the sky. What if the same technology is strapped down to the Earth? It will allow the observation and understanding of minute changes of the rate of rotation as well as variations of the orientation of the instantaneous axis of rotation of the Earth. Unlike the response of the Earth as a whole, aircraft motion is highly dynamic. Therefore we have to make a suitable gyro
for the application in the Geosciences significantly more sensitive and stable than aircraft gyros, improving their performance by many orders of magnitude.

This includes the mitigation of error sources that are not directly related to the rotation sensing process in the interferometer. As a result of that, we were able to reduce the measurement error of the 16 m 2 G ring laser of the Geodetic Observatory Wettzell to the point where rotational components of microseismic ground motion can be readily obtained.

Until now most of the investigations on large ring laser gyroscopes were dealing with a single component ring laser, placed horizontally on the ground. Over the recent years we have constructed a large 4-component ring laser structure, which is arranged in the form of an inverted tetrahedron with the tip in the ground. For the first time this arrangement can provide three dimensional rotation measurements with extra redundancy.

On this road towards the high resolution monitoring of a global measurement quantity (Earth rotation) with a local sensor (ring laser), we have encountered a number of serious challenges. This talk illustrates the recent progress in high resolution Sagnac Interferometry and its application to space geodesy and beyond.

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