High-Performance Hybrid-Reluctance-Force-Based Tip/Tilt System: Design, Control, and Evaluation

This paper presents the design, assembly, and evaluation of a novel integrated two degree of freedom (2DoF) actuator design for tip/tilt motion and its integration into a fast steering mirror with comparably large range. The system is designed for scanning applications, such as in optical metrology systems, and comprises an integrated symmetric 2DoF hybrid-reluctance-force actuator and moverflexure-design. The actuator design employs a permanent magnet for biasing the actuator with a constant flux and two actuator coils per axis to generate a steering flux for positioning the mover. The system prototype has an angular range of ±3° in tip and tilt and achieves a closed-loop control bandwidth of 1 kHz based on the signal of eddy current sensors. Compared to the only so far realized state-of-theart reluctance force actuated fast steering mirror system with integrated sensors, the presented design enables to improve the product of range times' bandwidth, representing a measure for the system performance, by more than 85%.