The Auto a lignment S ystem of GEO 600

The Autoalignment System of GEO 600

Hartmut Groteand the GEO 600 team

Max-Planck Institute for Gravitational Physics

Amaldi, Perth 12-07-2001

Autoalignment - Purposes

Superimpose cavity axes with incoming beam - Differential wavefront sensing (analog feedback for 14 DOF)

Center beam spot positions on mirrors - Spot position sensing (digital feedback for 20 DOF)

Autoalignment

Experimental setupfor 1 cavity

Autoalignment

Differential wavefrontsensing

Orthogonalization< 1/10

Bandwith 0.2 or 6 Hz

Sensitivity typ.10 p rad / sqrt(Hz)

Autoalignment

Local beam centeringservos

Bandwith ~ 1kHz

Autoalignment

Spot position control

Autoalignment - Switching On and Off

Modecleaner Alignment Drift Over 1 Day

Autoalignment setup

PR + MI cavity

PR Mirror Rotation Autoalignment Errorsignal

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