AO@SW with Vrala: Simulations and Tests

Abstract

Designed to actuate large correction forces on small spatial scales for the next generation deformable mirrors, VRALA is the ideal candidate for the Adaptive Optics actuators at visible wavelengths. Using its electric characteristics variations, properly supplying current commands, and optimizing the magnetic circuit geometry, the required force is delivered with a correction bandwidth of 2 kHz, and a 25 mm actuation density can be achieved. The dual-stator, single-mover soft magnetic composite core provides unprecedented performances with a negligible thermal impact. Pre-shaping the coil currents required to deliver a given stroke greatly simpli es the control system. Equipped with an inductance measure circuit, the current generator also provides the control system with an accurate feed-back signal. The Comsol non-linear model of VRALA allows to de ne the optimized geometry, to compute the dynamic response to the closed-loop control system, and to calculate the circuit inductance. The tests performed on a preliminary prototype, built according to the Comsol analyses, match the design results in terms of power and force

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