The AIMS, a solar telescope with a primary mirror of 1m in diameter, is designed with an off-axis Gregorian optical system and an alt-az mounting structure. The image rotation of the AIMS will be produced both due to alt-az mounting and the movement of plane mirrors system during the monitoring of the sun. Therefore, a derotator is planned to correct and compensate the image rotation to make the terminal instruments of the AIMS work properly. The image rotation in astronomical telescopes consists of the object field rotation and the image field rotations. In this paper, the rotation of the object field for the AIMS is presented and calculated. The image field rotation due to the plane mirrors system with the movement of azimuth axis and altitude axis of the AIMS is theoretically determined by using the ray tracing and vector matrix method. The relationships between the image filed rotation and the variation of the azimuth and altitude of the telescope are discussed. This work may be very helpful to evaluate the deroation methods for the AIMS and will provide an important theoretical support for precision control of the derotator to eliminate the image rotation in real time.
The primary mirror of AIMS solar telescope is heated during the observation of the sun, leading to temperature rise of the primary mirror. The temperature difference between the primary mirror and the surrounding air may cause the seeing effect (mirror seeing), which is one of the key factors influencing the image qualities of the telescope. In this paper, the temperature fields of the primary mirror and its surrounding air are simulated by the CFD software on the conditions of different ambient wind speeds, different observational angels of the primary mirror, and the duration of observation. According to the calculation of temperature fields, the mirror seeing on different conditions are analyzed and the necessity of thermal control of the primary mirror is evaluated. The evaluation of the mirror seeing is very helpful for the design of thermal control of the primary mirror.