Deformable magnetic mirror for adaptive optics: technological aspects

Ground-based telescopes suffer from atmospheric turbulences which perturb the quality of the light arriving from space. Astronomers use adaptive optics in order to correct the wavefront of oncoming light. In this context, a prototype of electromagnetic miniature (Ø 50 mm) deformable mirror is developed, using available microtechnologies. The mirror is composed of a thin polymer membrane (2–5 μm) covered with a matrix of permanent magnets, and of an array of planar microcoils on a Ø 50 mm substrate. The paper presents the various technologies used to build the actuator (membranes, coils, magnets). The mechanical behaviour of the mirror is tested. Deformations of up to 20 μm are achieved with currents in the range 1–3 A (6.6 μm/A). Resonance occurs at 485 Hz, with good linearity up to 200 Hz