Performance of the XMM optical vertical test facility

摘要

The x-ray multi-mirror mission is one of the four 'cornerstone' projects in the ESA Long-Term Program for Space Science. A vertical test facility to assess the optical quality of individual XMM optics and of each of the complete telescopes has been built at the 'Centre Spatial de Liege.' The main feature of this facility is its vertical optical axis in order to avoid earth gravity induced mechanical deformations of the thin optical shells. The originality of the facility is to use an extreme ultra- violet (548 angstrom) full illumination collimated bean (800 mm diameter), to minimize the diffraction effect and obtain image quality of the full aperture; to operate with an x-ray pencil beam to acquire the data of the scattering or surface quality of the mirrors; and finally, to work with a partial illumination collimated x-ray beam to measure the image quality of a sector. After description of the vertical test facility, the alignment of the optical stimuli and the overall performance of the facility are presented and discussed. These performance are controlled with a demonstration model of an XMM mirror module.