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). Keywords: spectral region of the "water window" multilayer free-standing filters, ultimate pressure difference, film filter strength, transmittance in the soft x-ray, visible light blocking level.

A project of an X-ray monochromator for the "SKIF" synchrotron based on two flat mirrors with multilayer reflective coatings is reported. The concept of the monochromator is based on the absence of precision mechanical systems and feedthroughs in vacuum, which significantly reduces mirror surface contamination and increases scanning accuracy. In addition, the overall structure of the device is greatly simplified in this way, which in turn leads to a significant reduction in the total cost and labor for manufacturing. The grazing angle of incidence of radiation on the mirrors in the process of scanning by photon energy varies within 0.5-1.3o. The length of the mirrors is 120 mm, the assumed size of the input beam is 1x1 mm2. A wide operating energy range, 8-36 keV, is achieved through the use of 3 strip-mirrors with coatings of different chemical composition, namely: Mo/B4C, W/B4C and Cr/Be. The article presents the X-ray optical scheme, the expected reflection coefficients and spectral selectivity of the monochromator, the results of the calculation of thermally induced surface deformations and the corresponding slope errors of the first mirror. Keywords: synchrotron radiation, multilayer mirror, monochromator, surface.

Within the Universat program, a set of solar vacuum ultraviolet (VUV) telescopes has been developed for deployment on 6U nanosatellites. Telescopes are designed to get images of the solar corona. The spectral ranges of observations is considered, the characteristics of the nanosatellite from the point of view of the observations feasibility are opmized, the optical scheme of the telescope and VUV multilayer mirrors coatings and thin-film filters are modelled. Keywords: Nanosatellite, VUV, telescope, solar corona.

The paper describes the design of a microscope for studying a betatron radiation source based on the PEARL femtosecond laser complex in the SXR and EUV wavelength range. The main optical element of the microscope is a spherical Schwarzschild objective a x5 magnification. The device allows to study the size and spatial structure of the interaction area of laser radiation with matter, at a selected wavelength in the EUV or SXR range with a resolution of delta x=2.75 μm. The operation wavelength (λ=13.5 nm) is set by multilayer X-ray mirrors. Thin-film absorption filters are used to suppress the background component of the signal. Keywords: SXR and EUV radiation, betatron radiation, imaging x-ray optics, SXR microscope.