AAS 195th Meeting, January 2000
Session 88. Space Missions and Techniques
Display, Friday, January 14, 2000, 9:20am-6:30pm, Grand Hall

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[88.04] Optimization of Grazing Incidence Optics for Wide-Field X-Ray Survey Imaging

P. W. A. Roming, D. N. Burrows, G. P. Garmire, W. B. Roush (Penn State University)

Optimization of wide-field X-ray optics could greatly enhance X-ray surveys. Discussions of optimizing wide-field X-ray optics, with field-of-views less-than 1.1 degree-squared, have been made previously in the literature. However, very little has been published about the optimizing of wide-field X-ray optics with larger fields-of-view.

We have been working on the design of a wide-field (3.1 degree-squared field-of-view), short focal length (190.5 cm), grazing incidence mirror shell set, with a desired rms image spot size of 15 arcsec. The baseline design incorporates Wolter I type mirror shells with polynomial perturbations applied to the grazing incidence surface. By optimizing the polynomial, the rms image spot size can be minimized for a large range of grazing angles. The overall minimization technique is to efficiently optimize the polynomial coefficients that directly influence the angular resolution, without stepping through the entire multidimensional coefficient space. The multidimensional minimization techniques that have been investigated include: the downhill simplex method; the coupling of genetic algorithms with full and fractional, including Plackett-Burman, factorial designs; and the coupling of genetic algorithms with Box-Behnken and central composite response surface designs. We have also examined the use of neural networks, coupled with genetic algorithms, as a method of multidimensional minimization. Investigations of backpropagation, probabilistic (PNN), general regression (GRNN), and group method of data handling (GMDH) neural networks have been made. We report our findings to date.

This research is funded by NASA grant #NAG5-5093.

The author(s) of this abstract have provided an email address for comments about the abstract: roming@astro.psu.edu

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