PRIMA-testbed

The PRIMA instrument for the VLT Interferometer is shown here during testing in Garching. The two combined beams of the PRIMA fringe sensor unit (FSU) B are seen, in red metrology laserlight, joining the FSU’s beam combiner in the background to the fibre injection optics. When complete the facility is expected to provide improvements in VLTI sensitivity, along with astrometry to better than 100 microarcseconds.