The Study On Test Technology Of The Extreme Ultraviolet Solar Telescope

With the development of space technology, the solar observation in space has become a significant part of the space astronomy in the extreme ultraviolet and soft x-ray region. As one of most important sun observation devise, the space solar telescope can provide important physical basises and new methods for the studies on solar activity and space weather. The extreme ultraviolet solar telescope (EUT) is the first EUV band imager in China for solar observation. In this dissertation, the ground tests and performance evaluations of the EUT are systematically investigated for future on-orbit applications.The optical design of the EUT is discussed in detail and the aberration effects due to the misalignments of the optical elements are analyzed. The applications of the computer aided alignment (CAA) method in actual assembly and adjustment of the EUT are discussed. The place offsets of the secondary mirror determined accurately by CAA are used to calculate the angular resolution of the EUT at 30.4 nm.The stray light exists in the ground test and on-orbit applications for the EUT. A system is established to measure the point source transmittance (PST) of the stray light in the EUT. The main source of the stray light is found by analyzing the telescope’s structure and the results of the PST test. Baffles are performed to block the first order stray light of the EUT and the resulting veiling glare index is 1.31%, which provides basis for the ground-based imaging test and guarantees the accuracy of the resolution test. The performance of the multilayer mirror and metal-film filter are calibrated and the transmittance of the EUT is 5.06×10-4 calculated by the calibration results. The design of the collimator which is used in the imaging test is discussed in detail. The resolution imaging test is performed to estimate the imaging ability of the EUT. The results indicate that the angular resolution is 0.96" which closed to the diffraction-limited performance (0.9") at 404.7nm.After the imaging test is done, the scatter at working wavelength is mainly studied. The scatter effects due to the mirror’s surface roughness are discussed and a calculation method for the resolution of the EUT is presented. Based on the practical measured PSD data of two mirrors, a model of the EUT is established and the resolution reduction due to the scatter is calculated to be 0.08" at 30.4nm. The optical resolution of the EUT is calculated to be 0.37" in an indirect way and the whole system resolution of the EUT was 0.85" with a CCD of 13μm/pixel.