Multilayer interference structures acting as dispersion elements for a mirror spectrometer for a wavelength range of 7-30 nm have been calculated and synthesized. Three elements are implemented: for the range λ=7-12 nm – multilayer structure Mo/B4C (periods N=60; period thickness d=6.50 nm); for the range λ=11-18 nm – Mo/Be (N=50; d=9.83 nm) and for the range λ=17-30 nm – Be/Si/Al (N=40; d=18.2 nm). For the entire spectral range, an efficiency of more than 10% was obtained at a wavelength resolution of 0.15-1.0 nm.

Some variants of the composition of multilayer absorption film filters with a high transmittance in the spectral region of the “water window” (2.3–4.4 nm) have been considered. Having created an ultimate pressure difference between the sides of free-standing films at which they are damaged, we compared the strength of 100 nm thick Ti-based multilayer filters with Al, Be, C interlayers and 100 nm thick V-based multilayer filters with Al interlayers. Sc and Cr was also considered as interlayers. Among the tested periodic multilayer structures, the best strength characteristics were demonstrated by Ti/Be (with a fraction of Ti in a period of about 0.6) and V/Al (with a fraction of V in a period of about 0.4) multilayer filters. Despite the fact that Ti/Be and V/Al filters are inferior in strength to Ti and V monolayer filters of the same thickness, these multilayer filters may be of interest, since they have either a higher transmittance in the “water window” (Ti/Be) or more high level of blocking of visible radiation (V/Al).