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Proceedings Paper

Solar X-ray Imager (SXI) optical performance analysis
Author(s): Martin E. Smithers; David E. Zissa
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Paper Abstract

The solar x-ray imager (SXI) telescope has a Wolter-I design with both grazing-incidence mirrors made from a single Zerodur substrate. The mirror fabrication requirements were for 40 percent encircled energy within 5-arc-seconds image diameter at an x-ray wavelength of 8.34 angstrom and for 56 percent, at 44.8 angstrom. The low-spatial-frequency mirror- surface error allocations (including on-orbit effects) were predicted to contribute (Using the ray-trace program GRAZTRACE) a geometric-image core of 3.34 arc seconds RMS diameter. The allocated mid- and high-frequency mirror surface errors had RMS values of 94 angstrom and 5 angstrom, respectively. The x-ray scattering program EEGRAZ was used to predict the resulting 5-arc-second diameter image encircled energies of 48 percent and 67 percent at 8.34 angstrom and 44.8 angstrom, respectively. These predictions exceeded the requirements. The characterization of the mirror as actually fabricated was accomplished using a ZYGO interferometer, a circularity test stand and a WYKO interferometer. Based on this data, the predicted geometric- image core RMS diameter was 4.03 arc seconds. The measured mid- and high-frequency surface errors had RMS values of 104 angstrom and 7.2 angstrom, respectively. Thus the allocated tolerances were not met. The resulting predicted encircled energies at 5-arc-second diameter were 32 and 52 percent at 8.34 angstrom and 44.8 angstrom, respectively. THese values fall short of the requirements for mirror fabrication by a small margin. The actual performance of the SXI mirror will be experimentally tested. The results will then be compared with the predictions.

Paper Details

Date Published: 19 July 1996
PDF: 6 pages
Proc. SPIE 2805, Multilayer and Grazing Incidence X-Ray/EUV Optics III, (19 July 1996); doi: 10.1117/12.245084
Show Author Affiliations
Martin E. Smithers, NASA Marshall Space Flight Ctr. (United States)
David E. Zissa, NASA Marshall Space Flight Ctr. (United States)


Published in SPIE Proceedings Vol. 2805:
Multilayer and Grazing Incidence X-Ray/EUV Optics III
Richard B. Hoover; Arthur B. C. Walker, Editor(s)

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