The alignment of the aerospace Cassegrain telescope primary mirror and iso-static mount by using CMM

Abstract

In order to meet both optical performance and structural stiffness requirements of the aerospace Cassegrain telescope, the primary mirror shall be mounted with the main plate by iso-static mount. This article describes of the alignment of the aerospace Cassegrain telescope's primary mirror and iso-static mount by using coordinate-measuring machine (CMM), and the design and assembly of mechanical ground support equipment (MGSE). The primary mirror adjusting MGSE consists of three 3-axis linear stages and point contact platforms, which hold the mirror while avoid the rotated movement when adjusting the stage. This MGSE provide the adjustment of tilt and height for the mirror. After the CMM measurement, the coordinates of measured point on the mirror will be analyzed by the software based on least square fitting to find the radius of curvature, conic constant, de-center and tilt, etc. According to these results, the mirror posture will be adjusted to reduce de-center and tilt by the designed MGSE. The tilt in x and y direction are reduced within 0.001 degrees and the distance deviation from the best fitted profile of the mirror to the main plate shall be less than 0.008mm.