Oscillations, Waves, and Interactions - GWDG

Variation in Area [*1e6]
3.0
2.0
1.0
0.0
-1.0
-2.0
-3.0
Large ring laser gyroscopes 293
970
0 4 8 12 16
Time [days in 2006]
Figure 12. Time series of the variations in effective ring laser area superimposed with the
atmospheric pressure at that time.
series of the atmospheric pressure as measured inside the cavern shows significant
correlation with these changes in area. From that one may conclude that pressure
induced deformations of the cave are causing small tilts at the mirror mounts, which
in turn cause beamwalk on the next mirror. A similar result is obtained for the
instantaneous orientation of the UG2 ring laser as shown in Fig. 13. The contributions
from ring laser reorientation are smaller by a factor of about two compared to the
variations in area. Nevertheless the corrections to the orientation vector are also in
the parts per million regime and can not be neglected. Again there is some correlation
with the atmospheric pressure evident as well as a linear overall trend. As opposed to
orientation and area, the computed perimeter changes are approximately six orders
of magnitude smaller as shown in Fig. 14. This is compatible with the general
observation that longitudinal mode index changes are infrequent.
Variation in Orientation [ * 1e6]
1.0
0.0
-1.0
-2.0
-3.0
-4.0
1030
1020
1010
1000
990
980
970
0 4 8 12 16
Time [days in 2006]
Figure 13. Time series of the variations in effective ring laser orientation superimposed
with the atmospheric pressure.
1030
1020
1010
1000
990
980
Atmospheric Pressure [hPa]
Atmospheric Pressure [hPa]