LIGO Document P1400198-v2

Loss Dependence on Beam Position in the Arm Cavities of aLIGO

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P - Publications
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High beam power in the interferometer is an essential component to realize
required sensitivity to Gravitational waves. Therefore it is signi cant to un-
derstand main factors which cause optical loss in the arm cavities although we
have not completely veri ed the effect of these factors on power loss. In this
project we introduce the simulating model of the optical loss, called the clipping
model, and investigate the loss dependence on beam off-centering on the test
mass. An informative method which we adopt in the measurement makes it
possible to derive not only optical loss but also other optical values. We also
discuss some noise caused by Input Mode Cleaner in order to estimate accurate
loss quantities. As a result, we con rm that the loss dependence appears to be
consistent with the clipping model. However we cannot evaluate the agreement
statistically between theory and practice because of the shortage of experimen-
tal data. Thus more data at various spots on the optics are required as a future
work in order to make precise maps of the mirror with optical losses.
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