We have fabricated periodic multilayers that comprise either or bilayers, designed to operate as narrowband reflective coatings near 60 nm wavelength in the extreme ultraviolet (EUV). We find peak reflectance values in excess of 20% near normal incidence. The spectral bandpass of the best multilayer was measured to be 6.5 nm full width at half-maximum (FWHM), while multilayers have a more broad response, of order 9.4 nm FWHM. Transmission electron microscopy analysis of multilayers reveals polycrystalline Tb layers, amorphous Si layers, and relatively large asymmetric amorphous interlayers. Thermal annealing experiments indicate excellent stability to 100°C (1 h) for . These new multilayer coatings have the potential for use in normal incidence instrumentation in a region of the EUV where efficient narrowband multilayers have not been available until now. In particular, reflective multilayers can be used for solar physics applications where the coatings can be tuned to important emission lines such as O V near 63.0 nm and Mg X near 61.0 nm.
© 2005 Optical Society of AmericaFull Article | PDF Article
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