LIGO Document P1000148-v1
- Advanced LIGO will soon be operative with a strain sensitivity of 4e-24 1/rHz. To achieve this sensitivity, the interferometer will have to operate exactly at its ideal working point. By using the Caltech LIGO 40m interferometer prototype as a model of the Advanced LIGO interferometers, we show how mismatches between the optical design parameters and the actual configuration of the optical cavities may compromise the performance of the detector. We then discuss how cavity absolute length tolerances can be defined based on the results of this analysis. To determine the actual mismatch of the optical cavities from the ideal design, we developed an interferometric technique to measure absolute length and g-factor of the arm cavities and the recycling cavities of the interferometers. We show how the tools developed for this analysis will be of immediate application during the installation and the commissioning of the Advanced LIGO interferometers.
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