Abstract: This article first deals with general aspects ofoptimizing mirror supports. A wide variety of supporttopologies have been optimized by Nelson et al forunobscured entrance pupils. Optical forces andlocations of point supports have been calculated herefor annular pupils. Efficient topologies introducing asmall amount of defocusing are also proposed forunobscured and annular pupils. Support efficiencies aregiven for each topology. Wavefront errors are estimatedin the case of a defective cell, in order to specifytolerances on forces and geometries. The OVLA activeoptics is then discussed. The very thin,meniscus-shaped primary will be actively supported by29 actuators and 3 fixed points. Actuator locations andforces have been calculated to minimize the mirrordeflection under its own weight but also to allow agood control of astigmatism. We finally present a studyof a concave adaptive secondary for the OVLAtelescopes. As an initial result, we propose a defocusadaptive corrector with a variable thicknessdistribution. Conditions of use are defined, andperformances are evaluated.!13
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