The DARWIN breadboard cryogenic optical delay line

TNO, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboardcryogenic delay line (figure 1) for use in future space interferometry missions. The work is performed under ESA contract 17.747/03 in preparation for the DARWIN mission. The breadboard(BB) delay line is representative of a flight mechanism. The delay line has a single stage voice coilactuator for Optical PathDifference (OPD) control, driving a twomirror cat’s eye. Magnetic bearingsprovide frictionless and wear free operation with zero-hysteresis. The design of the BB delay line has been completed. The development testprogram, including operation at 100 K has been completed. The verification test programme is currently being carried out and will include functional testing at 40 K.