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1 February 1991 Performance of the Multi-Spectral Solar Telescope Array IV: the soft x-ray and extreme ultraviolet filters
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The multilayer mirrors used in the nonnal incidence optical systems of the Multi-Spectral Solar Telescope Array (MSSTA) are efficient reflectors for soft x-ray/extreme ultraviolet (EUV) radiation at wavelengths that satisfy the Bragg condition, thus allowing a narrow band of the soft x-rayfEUV spectrum to be isolated. However, these same mirrors are also excellent reflectors in the visible, ultraviolet, and far ultraviolet (FUV) part of the spectrum, where normal incidence reflectivities can exceed 50%. Furthermore, the sun emits far more radiation in the ultraviolet and visible part of the spectrum than it does in the soft x-rayIEUV. For this reason, thin foil filters are employed to eliminated the unwanted longer wavelength solar emission. With the proper choice of filter materials, the filters can also be used to eliminate EUV radiation at longer wavelengths, where the increasing specular reflectivity of multilayer mirrors and the high intensity of solar emissions can cause "contamination" of the image in the narrow band defined by the Bragg condition. In addition, filters can eliminate higher order multilayer reflections. Finally, filter absorption edges can sometimes be utilized to reduce the width of the primary bandpass. The MSSTA instrument uses various combinations of thin foil filters composed of aluminum, carbon, tellurium, potassium bromide, beryllium, molybdenum, rhodium, lexan, and phthalocyanine to achieve the desired radiation rejection characteristics. The filters are currently being manufactured by Luxel Corporation of Friday Harbor, Washington, and Penn-Spectra Incorporated of Wallingford, Pennsylvania. This paper discusses issues concerning the design, manufacture, and performance of the MSSTA filters.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Joakim F. Lindblom, Ray H. O'Neal, Arthur B. C. Walker II, Forbes R. Powell, Troy W. Barbee Jr., Richard B. Hoover, and Stephen F. Powell "Performance of the Multi-Spectral Solar Telescope Array IV: the soft x-ray and extreme ultraviolet filters", Proc. SPIE 1343, X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography, (1 February 1991);


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