Figure measurement of AIMS primary mirror using sub-aperture stitching interferometry

Abstract

The national major scientific research instrument project: "The accurate infrared solar magnetic field measurements system" (AIMS) is under construction. The figure of the primary of the AIMS can be measured using a computergenerated hologram (CGH) test during the polishing process, however, a distortion correction procedure is needed to mapping the coordinates of the mirror and the pixels of fringes due to the large distortion exists in the CGH test configuration, and the mapping relationship need to be re-calibrated after the primary mirror was reassembled, which makes the test process cumbersome. In this paper, a sub-aperture stitching equipment was established, which uses a twodimensional guide that can move a 450mm reference flat mirror to any position that can cover the aperture of the primary mirror. The surface shape requirement of the 450 mm flat mirror was given by Monte-Carlo analysis and further the figure was tested by using Ritchey-Common technique. Furthermore, a sub-aperture stitching test system was established and a modified simultaneous fitting algorithm was proposed to stitch the sub-aperture wavefront together, the correctness of the technique was verified by a full aperture figure test experiment. Finally, we applied the developed approach to the site test of figure of the AIMS primary mirror.

Optical alignment technology for 1-meter accurate infrared magnetic system telescope

“…Obviously, 450 mm flat mirror cannot cover the full aperture of the primary mirror, a subaperture stitching interferometry method is employed. 13 The principle is depicted as follows. Different 450 mm diameters of the primary mirror surface are measured by two-dimensional translation of the 450 mm flat mirror.…”