Automatic beam alignment for the mode-cleaner cavities of GEO 600

Hartmut Grote*, Gerhard Heinzel, Andreas Freise, Stefan Goßler, Benno Willke, Harald Lück, Harry Ward, Morag M. Casey, Kenneth A. Strain, David Robertson, Jim Hough, Karsten Danzmann

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


The automatic alignment system for the two suspended, triangular mode-cleaner cavities of the gravitational wave detector GEO 600 has been in continuous operation since the spring of 2001. A total of 20 angular degrees of freedom are controlled by feedback loops with almost no manual alignment having been required since installation. Error signals for the eight most important degrees of freedom are obtained with the differential wave-front sensing technique. We describe the sensing system, the control topology, and the performance of the automatic alignment system. A continuous locking stretch of more than 120 h has been achieved.

Original languageEnglish
Pages (from-to)1938-1945
Number of pages8
JournalApplied Optics
Issue number9
Publication statusPublished - 20 Mar 2004
Externally publishedYes


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