Deformable magnetic mirror for adaptive optics: technological aspects

Ground-based telescopes suffer from atmospheric turbulences which perturb t he quality of the light arriving from space. Astronomers use adaptive optic s in order to correct the wavefront of oncoming light. In this context, a p rototype of electromagnetic miniature (diameter 50 mm) deformable mirror is developed, using available microtechnologies. The mirror is composed of a thin polymer membrane (2-5 mum) covered with a matrix of permanent magnets, and of an array of planar microcoils on a diameter 50 mm substrate. The pa per presents the various technologies used to build the actuator (membranes , coils, magnets). The mechanical behaviour of the mirror is tested. Deform ations of up to 20 mum are achieved with currents in the range 1-3 A (6.6 m um/A). Resonance occurs at 485 Hz, with good linearity up to 200 Hz. (C) 20 01 Elsevier Science B.V. All rights reserved.