This paper describes the features of the two-mirror adaptive system for correcting atmospheric disturbances of the Large Solar Vacuum Telescope, developed with allowance for the correction of instrumental vibrations of telescopes in a wide amplitude-frequency range with an open siderostat supply mirror. Correction of the general slopes of the light wave front and its deformations is carried out separately. The adaptive optical system is designed to work with extended light sources (the Sun), which have a low contrast of image details.
Developed according to quasi-Ritchey–Chretien, the AZT-33VM telescope is designed for up to 2.8-deg wide-field survey observations; it has inner position of the focal plane and the prefocal lens corrector installed at 0.12 of the equivalent focal length from the image plane. Classic methods to calculate direct stray light protection system in two-mirror systems allow us to find the optimal configuration of the baffles providing minimum obscuration of the entrance pupil. The design of stray light protection baffles for a future large rectangular detector 260 × 124 mm was proposed. The baffles were calculated from axisymmetric condition in a plane passing through the system centerline and a point of the detector perimeter. Using the ray-tracing method, we simulated optimized baffles for a rectangular detector. We assessed obscuration of the entrance pupil with an optimal design baffle as well their advantages for the modulation transfer function.
The ground-based 0.36m mirror coronagraph with super-polished off-axis parabolic primary mirror for solar
applications has developed and build now. Optical system design, technology of scattering level measurement of
primary mirror surface and the method of adjustment are described. Also presents the constructions of heat-stop, Lyot-stop
assemblies and truss. The kit of spectral equipment and detectors for actual solar astrophysics tasks is discussed.
Two-mirrors aplanatic optical design for amateur telescopes up to 0.5m class is described. The optical system is low cost,
easy for adjusting, fast and large field of view can be used for visual and astrophotography. The method for calculation
of baffles for straight light protection is described. The optical performances and sample shots for the builted device are
Keywords: two-mirrors system, all-reflecting schmidt system, aplanatic system, protection from straight light, baffles,
obscuration, wide-field, telescopes for amateurs.
The devices and components of adaptive optical system ANGARA, which is developed for image correction in the Big
solar vacuum telescope (BSVT) at Baykal astrophysical observatory are described. It is shown that the use of
modernized adaptive system on BSVT not only reduces the turbulent atmospheric distortions of image, but also gives a
possibility to improve the telescope developing new methods of solar observations. A high precision Shack-Hartmann
wavefront (WF) sensor has been developed on the basis of a low-aperture off-axis diffraction lens array. The device is
capable of measuring WF slopes at array sub-apertures of size 640X640 μm with an error not exceeding 4.80 arc.sec.
Also the modification of this sensor for adaptive system of solar telescope using extended scenes as tracking objects,
such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF
sensors includes three algorithms of local WF slopes estimation (modified centroids, normalized cross-correlation and
fast Fourier-demodulation), as well as three methods of WF reconstruction (modal Zernike polynomials expansion,
deformable mirror response functions expansion and phase unwrapping), that can be selected during operation with
accordance to the application.
The design sophistication of optical instruments with low level instrumental (including diffraction) scattered illumination is very interesting not only for solar asrophysics. The construction of a laboratory installation for measuring intensity of a diffractio-swcattered illumination in a shadow of darkening system of a coronagraph with an exterior eclipse surveyed is described. The method of measuring, permitting to minimize influecing of a light, scattered from interior surfaces of installation is offered. Measuring of intensity of a diffraction-scattered illumination in a shadow of the single disk with different lateral views of edge is conducted. From the obtained experimental data follows that the change of the shape of scattering edge of exterior darkening system can essentially reduce intensity of a diffraction-scattered illumination in the field of an entrance pupil of an external occulted coronagraph.