Once we had the high power pre-stabilized laser, the optics on the suspensions, and the seismic isolation stages, each piece installed and commissioned by the subsystem team, we were ready to commission the “dual recycled Michelson interferometer,” known in the control room as DRMI.
Keiko Kokeyama continues.
During the early phase of the DRMI commissioning, a number of unexpected things happened. We found that even a simple Michelson interferometer could not be locked without the optical lever damping in addition to the local damping loops of suspension actuators.
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From Life
at the
Louisiana Site, LIGO Magazine. pdf 
This is real. Contrast Treknobabble
See The Scout Report post