A Fast Steering Mirror Using a Compact Magnetic Suspension and Voice Coil Motors for Observation Satellites

Abstract

Fast steering mirrors (FSMs) are used to correct images observed by satellites. FSMs need to have large apertures and realize high precision and the positioning of the mirror in the tip-tilt and axial directions needs to be highly precise and highly responsive in order to capture large-scale, high-resolution images. An FSM with a large-diameter mirror supported by a compact magnetic suspension and driven by long-stroke voice coil motors (VCMs) is proposed in this paper. The magnetic suspension and VCM actuators enable the mirror to be highly responsive and to have long-range movement in the tip-tilt and axial directions without friction and wear. The magnetic suspension is a hybrid that has active control in the lateral directions and passive support in the tip-tilt and axial directions. An experimental FSM with an 80 mm diameter dummy mirror was fabricated and tested. The mirror’s driving ranges in the tip-tilt and axial directions were ±20 mrad and ±500 μm, respectively. Furthermore, the servo bandwidths in the tip-tilt and axial directions were more than 1 kHz and 200 Hz, respectively.