Design of a Tunable Resonant Scanning Mirror
J. LI (TU Delft - Mechanical Engineering)
Ron A.J. van Ostayen – Mentor (TU Delft - Mechatronic Systems Design)
J.P. Kappelhof – Mentor (TU Delft - Optical Technologies)
Jo W. Spronck – Graduation committee member (TU Delft - Mechatronic Systems Design)
GV Vdovin – Graduation committee member (TU Delft - Team Raf Van de Plas)
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Abstract
Scanning mirror is a widely used device in many optical systems to position reflected beam. Existing products include galvanometer and resonant scanner. They are intended for accurate positioning at low frequency range and fast scanning at the specified high frequency respectively. However, when a wide frequency range is involved, they might not be able to fulfill the requirement. To solve this generic issue, Hittech starts to research new alternatives. In this paper, a novel solution is proposed, by tuning resonant frequency and exciting higher order modes to cover the intended frequency range 500 - 5k Hz. A flexure mechanism is designed, where the scanner contains a cantilever as resonator, and a cut-leafspring as hinge guiding to achieve 1 DoF resonant scan. Resonant frequency is tuned by clamping different positions of the cantilever by two surfaces with large radius of curvature, and sliding could be enabled by DLC coating. Concept and detailed design are evaluated by finite element modelling and a prototype is built. The test results show a good match with the simulation. The intended frequency range could be covered and the reflected beam could achieve a scanning angle of 1mrad. Unwanted motions of mirror are verified and limited within requirement with large margins, and hence could be negligible for operation.