Mullavey, Adam J.Slagmolen, Bram J. J.Miller, JohnEvans, MatthewFritschel, PeterSigg, DanielWaldman, Sam J.Shaddock, Daniel A.McClelland, David E.2016-05-132016-05-131094-4087http://hdl.handle.net/1885/101231Residual motion of the arm cavity mirrors is expected to prove one of the principal impediments to systematic lock acquisition in advanced gravitational-wave interferometers. We present a technique which overcomes this problem by employing auxiliary lasers at twice the fundamental measurement frequency to pre-stabilise the arm cavities' lengths. Applying this approach, we reduce the apparent length noise of a 1.3 m long, independently suspended Fabry-Perot cavity to 30 pm rms and successfully transfer longitudinal control of the system from the auxiliary laser to the measurement laser.This work was supported by the Australian Research Council. JM is the recipient of an Australian Research Council Post Doctoral Fellowship (DP110103472). LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under cooperative agreement PHY-0757058. This paper has been assigned LIGO Laboratory document number LIGO-P1100134.© 2011 Optical Society of AmericaKeywords: Cavity mirror; Fabry-Perot cavity; Gravitational wave detectors; Lock acquisition; Measurement frequency; Residual motion; Fabry-Perot interferometers; Gravity waves; Longitudinal control; Mirrors; article; artifact; equipment; equipment design; gravity;2011-12-1410.1364/OE.20.0000812016-06-14