Applicability of adaptive optics for solar telescopes

Abstract

We summarize the first results of the application of adaptive optics in a solar telescope. The optical experiments were accompanied by the measurements of local astroclimate characteristics near the Big Solar Vacuum Telescope (BSVT), at which the work to apply adaptive optics is carried out. The observations were performed in July 2005 under clear sunny weather conditions and in the almost complete absence of cloudiness. Based on meteorological measurements, we have calculated the local temperature stratification parameter, the Monin-Obukhov number. Tests of a modified correlation sensor (MCS) at the BSVT of the Baikal Astrophysical Observatory, Institute of Solar-Terrestrial Physics SB RAS (ISTP) have shown that the MCS reliably measures the shift of the solar granulation image at the first telescope focus for properly chosen parameters of the filtering function. During routine use of the adaptive optical system, the MCS should measure the image shift at the second telescope focus. The MCS turned out to measure the shift of the solar granulation image at the second telescope focus only under exceptionally good visibility conditions and for a certain granulation structure. Reducing the telescope entrance aperture to 170 mm only slightly affects the image quality and, hence, the MCS operation.