Testbed for an adaptive secondary mirror of 1.8m telescope

Testbed for an adaptive secondary mirror of 1.8m telescope is a system, which originates from Simpson-Oland-Meckel method. The testbed is composed of Hartmann-Shack (H-S) wavefront sensor, Hindle element and analysis element. Light from H-S wavefront sensor passes through the Hindle element and reflects off of the adaptive secondary mirror. It then is reflected by the concave surface of the Hindle element. After reflecting off of the adaptive secondary mirror again, it passes through the Hindle element and return to the H-S wavefront sensor. A beam splitter is placed between H-S wavefront sensor and Hindle element to reflect part of the output light to analysis element. The testbed is a low cost simple system that allows testing the convex hyperboloid adaptive secondary mirror. It also could be used to calibrate the adaptive secondary mirror as well as investigating higher performance control loops. Optical setup design, tolerance of fabrication, alignment and material asymmetry are presented in this paper.