1 June 1990 Metal multilayer mirrors for EUV/ultrasoft x-ray wide-field telescopes
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Abstract
Metal multilayer mirrors have been designed for the ALEXIS satellite, which is to carry six wide-field telescopes to perform an all-sky survey in three narrow EUV/ultrasoft x-ray wavelength bands. Comprised of alternating layers of molybdenum and silicon, the mirrors are optimized to provide maximum reflectivity at angles from 12.5 to 17.6° off normal incidence and at wavelengths of 133, 171, or 186 Å. Simultaneously, the mirrors use a "wavetrap" to suppress reflectivity at 304 Å, where the extremely strong geocoronal line of He II causes severe background problems. Low reflectivity at 304 Å is achieved by superposing two layer pairs that provide destructive interference with an effective 2d spacing of 152 Å. Calculations predict the 186 Å design will have a peak reflectivity at 186 A of 35% and a 304 Å reflectivity less than 10-5 compared to a peak reflectivity at 186 Å of 40% and 304 Å reflectivity of 3 x 10-3 without the wave- trap. In the laboratory the 304 Å reflectivity on a multilayer sample with a wavetrap has been measured to be as low as 10-4 . We present details of the calculations and laboratory measurements of the reflectivity performance obtained with prototype mirrors.
Barham W. Smith, Barham W. Smith, Jeffrey J. Bloch, Jeffrey J. Bloch, Diane C. Roussel-Dupre, Diane C. Roussel-Dupre, } "Metal multilayer mirrors for EUV/ultrasoft x-ray wide-field telescopes," Optical Engineering 29(6), (1 June 1990). https://doi.org/10.1117/12.55638 . Submission:
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