XMM flight-mirror-modules environmental and optical testing

Abstract

The X-ray Multi-Minor Mission is one of the four "Cornerstone" projects in the ESA Long-Term Program for Space Science. Presently, five XMM Minor Modules (MM) (including one Qualification Model) have been tested in the FOCALX facility of CSL. The MMs are illuminated by a vertical EUV (58.4 nm) collimated beam allowing to get the optical performance in an effective flight configuration. To fully analyse the MM characteristics, reflectivity measurements are performed in X-ray thanks to a pencil beam. The reflectivity measurements of single shell are performed at Al, Au, Cu, Mo lines between 1 .5and 1 3 keV. This information is used to evaluate the effective area in X-rays. Wing scattering measurements are performed and show a good correlation with the Power Spectral Density measured with a PROMAP microscope interferometer during minor shell manufacturing. This paper deals first with the presentation and comparison of the results achieved on the five MMs. In a second step the results of complementary tests, performed to cross check the data and to get a better understanding of the MM behaviour, are discussed.

Nanoscale measurement of the power spectral density of surface roughness: how to solve a difficult experimental challenge

“…The nanoscale surface morphology determines a wealth of phenomena which are important for fundamental science as well as for technological applications [1][2][3]. As is well known, surface roughness is a basic parameter in tribology [4,5], adhesion phenomena [2,6], the internal 3-D morphology of nanostructural functional materials [7], wetting properties of surfaces [8][9][10][11], optical reflectivity [12,13] as well as a wealth of biological processes [8,14]. A precise and reproducible measurement of surface roughness is therefore a key issue for basic science as well as for engineering applications [15].…”

The Reflection Grating Spectrometer on board XMM-Newton

“…This, and the individual figure measurements provides the optical figure of the assembly as a whole. The composite grating array figures were verified after the mating of the grating arrays to the XMM mirror modules, using a parallel UV beam at the Centre Spatial de Liège (Stockman et al 1998). In addition to the measurement list above, the following measurements were performed on a subset of gratings that helped constrain physical modelling of the RGS; in particular the grating reflectivity.…”

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“…As the off-axis angle increases, the PSF shape morphs from being circularly symmetric to ellipsoidal and finally bow-tie shaped. There have been a number of attempts to characterize the XMM PSF including: simulations based on measurements of the shape of the mirrors (Gondoin et al 1996); measurements taken on the ground by passing X-ray beams from synchrotron sources through XMM mirror modules (Stockman et al 1997;Gondoin et al 1998); and fitting one-dimensional profiles to observations of bright X-ray sources (Gondoin et al 2000;Ghizzardi 2001Ghizzardi , 2002Read 2004). Unfortunately, thus far, this has not resulted in a complete and reliable characterization of the XMM PSF.…”