Segmented active / adaptive thin shell mirrors

Current ELTs use comparatively thick segmented mirrors with a support structure / warping structure of significant mass. In this publication we present a method to develop Segmented Thin Shell Mirrors that shall be supported by multiple actuators mounted on a backing structure. This enables active and or adaptive segmented mirrors for a variety of applications. Starting with a Adaptive Secondary Mirror The pre and post surface form error was measured and compared. The difference between the two is17.7 µm peak-to-valley and 3.7 µm rms. The error is gradual and can easily be compensated by pre-loading the actuators that support and deform the mirror.