REPORT ON THE REDESIGN OF THE FIBRE LINK STABILISATION UNITS AT FLASH

Recently, the fibre link stabilisation unit of the optical synchronisation system at FLASH has been subject to several designchangesinvolvingsome majorissues. Enhancements of the optical design have led to improvementsin the efficiency of the free space optics and a new motorised optical delay line allows for a more than twice as long adjustment range. The amplitude noise, encountered previously at the remotestation of the links, couldbe furtherdecreased by a new beam splitting configuration. In this paper we report on the changes of the opto-mechanical design and we present first results from the recently commissioned links.