A large adaptive deformable membrane mirror with highactuator density

Model-Based Feedforward Control of Large Deformable Mirrors

“…100 μm) allows to approximate the spherical shell by a Kirchhoff plate. Similar assumptions are drawn in [12] for a comparable system. Therefore, it is assumed that the native curvature of the shell can be neglected due to only small deflections perpendicular to the surface.…”

“…Thereby, the assumed homogeneous mass distribution for the derivation of (12) is not fully met. Taking both effects into account, the modes in (12) do not fully describe the spatial dynamics of the shell, yet. However, it can be shown that the central membrane of low rigidity can be included in an analytic formulation of boundary conditions for the inner radius [23].…”

Simple unimorph deformable mirrors fabricated from piezo buzzers

“…In adaptive optical setups, the wavefront is controlled by a deformable mirror for which various different mechanisms of actuation have been demonstrated. Existing techniques include pneumatic principles (Moghimi et al 2014), thermal actuation (Vdovin and Loktev 2002), electromagnetic actuators (Hamelinck et al 2004, Wu et al 2011, ferrofluids (Brousseau et al 2008, Balderas-Mata et al 2011, and piezo actuators (Forbes et al 1989, Rodrigues et al 2009, Verpoort and Wittrock 2010, Rausch et al 2012. Among the latter, thin-film diaphragms with segmented electrodes are widely employed mostly for their design simplicity, low number of required components and high performance in terms of achievable speed and accuracy.…”

Electromagnetic deformable mirror development at TNO

“…Each actuation principle has its own advantages and disadvantages, and the best solution can change from application to application. Over the last decade TNO, in collaboration with the technical universities of Eindhoven and Delft, developed a deformable mirror concept using electromagnetic actuators [2,3]. Two prototype mirrors have been built with 61 and 427 actuators in a hexagonal grid with 6.3mm pitch, as is shown in Figure 1.…”

“…In many astronomy applications it is a strong wish, and sometimes a driving requirement, to be able to control the shape of the DM towards a predefined shape to allow imaging with reasonable quality in case the AO-loop is not active. Also Multi Object Adaptive Optics systems [3] and some forms of sensorless wavefront sensing [4] rely on open-loop shape control of the DM. This requires a highly stable and repeatable response of the DM which is one of the main assets of the electromagnetic actuation principle.…”