Adaptive secondary mirror demonstrator: construction and preliminary evaluation

Abstract

Adaptive optics (AO) combines technologies that enable the correction of the wavefront distortion caused by the earth's atmospheric turbulence in real time. Adaptive secondary mirror (ASM) systems have been proposed and are now being developed. ASMs have advantages over conventional AO systems in terms of throughput, polarization and IR emissivity. Previously, we reported the design of an ASM demonstrator along with its predicted performance. We now report the construction techniques and the results from the preliminary static and dynamic testing of such a demonstrator. In particular, assembly methods that preserve the optical quality of the mirror are presented along with experimentally measured mirror influence functions and closed loop tip/tilt performance.

First order analysis of thin plate deformable mirrors

“…From previous studies [2][3][4][5][6], for a mirror that was very stiff compared to the actuators, the influence functions were Gaussian which extended beyond the actuator by two to three times the actuator spacing. As the actuator stiffness was increased with respect to the mirror, the influence function became narrower, and less Gaussian in shape.…”

“…1) The overall performance is quite constant except the area 0 ≈ [4,5], can be used for analyzing the fitting ability of deformable mirrors. The analysis is performed also using a commercial matrix program [11] for the first six layouts of each equi-spaced actuator patterns.…”

Development of a carbon fiber composite active mirror: design and testing

“…The baseline specifications (Young's modulus, stiffness, actuator spacing) were made to match that of a previous deformable mirror system that was developed at UCL in the late 1990s. This system is described in detail by Lee et al [8] and Lee [9] and features an aluminium faceplate with a diameter of 27 cm, whose shape is controlled by 7 magnetostrictive actuators spaced at 10 cm in a hexagonal arrangement, plus full backing structure, drive electronics and software. Its form is concave and spherical, with a radius of curvature of 2945 mm.…”