The paper describes a wide-angle collimator based on a “Schmidt camera” mirror design, which is intended for resolution measurements of a telescope operating in the 120- to 380-nm wavelength range. The collimator consists of a test pattern, a spherical mirror, and a mirror wavefront corrector (planoid) compensating for spherical aberration and astigmatism. The test pattern is shifted from the optical axis of the collimator using a flat mirror. The main parameters of the device are as follows: working area diameter of the test pattern, 30 mm; aperture ratio, F/3.2; exit pupil diameter, 250 mm; angular resolution measured in “white light,” 1.4 arc sec; and field of view, 2ω=3 deg. The results of the angular resolution measurements of a two-channel Schmidt–Cassegrain mirror telescope, obtained with the use of the collimator, are given.
The work is devoted to the method of mounting and surface shape measurement of the primary mirror of ARCA telescope, intended for the Sun observation in EUV wavelength range. Calculation of mirror’s deformation due to weight is carried out and a method of its experimental determination in interferometer is proposed. The method of deformation-free installation of mirror into the telescope is proposed. Impact shocks and vibrations, arising during missile launch, is analyzed, and an optimal size of bridges in the rim is determined. Calculations of the mirror deformation due to temperature difference in the telescope on the Earth's orbit and its influence on the resolution of the telescope are conducted. The stresses arising in epoxy adhesive due to temperature changes and due to starting shocks are simulated.
ARKA and KORTES are two upcoming solar space missions in extreme ultraviolet and X-ray wavebands. KORTES is a sun-oriented mission designed for the Russian segment of International Space Station. KORTES consists of several imaging and spectroscopic instruments that will observe the solar corona in a number of wavebands, covering EUV and X-ray ranges. The surveillance strategy of KORTES is to cover a wide range of observations including simultaneous imaging, spectroscopic and polarization measurements. ARKA is a small satellite solar mission intended to take highresolution images of the Sun at the extreme ultraviolet wavelengths. ARKA will be equipped with two high-resolution EUV telescopes designed to collect images of the Sun with approximately 150 km spatial resolution in the field of view of about 10'×10'. The scientific results of the mission may have a significant impact on the theory of coronal heating and may help to clarify the physics of small-scale solar structures and phenomena including oscillations of fine coronal structures and the physics of micro- and nanoflares.