Image of the Week
Panorama of Gaia BAM in TNO clean room
The panorama shows the Gaia BAM in one of the TNO class 1000 clean rooms in the Van Leeuwenhoek Laboratory (VLL) in Delft, the Netherlands.
The large panoramic photo was composed of 53 high resolution images and stitched with PTGui. On the left hand side we see System Engineer Teun van den Dool and Optical Engineer Maria Sovago working on the optical test equipment. In the centre, on the large optical table, Optical Engineers Dick de Bruijn and Martin Eschen are completing the alignment of Bar #2. Further right MAIT Manager Jeroen Mekking and AIT engineer Cor Vermeulen are torqueing the bolts of the Iso Static Mounts of Bar #1. To the far right Project Manager Wim Gielesen and Test Engineer Fred Kamphues are preparing the periscope bolts with Intellifast Permanently Mounted Transducer System (PMTS) for accurate preload control.
TNO is developing the Basic Angle Monitoring Opto-Mechanical Assembly (BAM OMA) for Gaia. This on-board metrology system consists of two laser interferometers. Two pairs of parallel laser bundles are sent to the two telescopes, which create two interference patterns on a detector. If the basic angle varies, the interference patterns will shift. With the BAM an Optical Path Difference (OPD) as small as 1.5 picometer RMS can be measured.
The stability requirements for the BAM are extreme. The mirrors and beam splitters must have a tilt stability of less than 2 microrad during launch and cool down to operational temperature. In addition, the fibre collimator mirrors shall have a lateral stability of better than 500 nanometer.
For more information about the Gaia BAM, visit the TNO web site.
Image credit: TNO/Fred Kamphues
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