Active vibration filtering: application to an optical delay line for stellar interferometer

In December 1989, the first optical delay line was delivered to France's Observatorie de la Cote d'Azur (OCA) for the I2T stellar interferometer. In order to meet the very stringent stability requirement imposed on the delay line during its programmed translation, a servocontrolled stage for active vibration filtering has been developed and successfully tested. This paper first describes the requirements specific to this application. The need for active vibration filtering is then demonstrated, considering the state-of-the-art in translation stage technologies. After a brief description of the servocontrolled filtering stage and the overall interferometer's control architecture, the results obtained are presented. In the last section, we discuss the potential future applications of the developed concept.