A Free-Space Tunable Beam Expander Designed for Automated Assembly

The authors present the first reported free space tunable beam expander produced in the PolyMUMPs process that can be assembled using an automated prober. The optical system consists of an optic fiber guide and two Fresnel zone plates. One Fresnel zone plate is fixed to the substrate whereas the other is attached to an adjustable platform. The platform has a travel range of 330 mum and is powered by an electrothermal vibromotor. The combined system has a back focal length range of -2 mm to infinity and infinity to 1.6 mm depending on the position of the Fresnel zone plates. Detailed design and results for the fabricated device are presented in this paper.