3D Nano‐Printed Bistable Microlens Actuator for Reconfigurable Micro‐Optical Systems

Abstract

The integration of multiple functional microscopy methods into a single, miniaturized instrument, known as multimodal endomicroscopy, presents significant challenges due to the often conflicting optical requirements of each imaging modality. In this study, the use of 3D nano‐printing based on two‐photon polymerization for the monolithic manufacturing of complete optical MEMS devices is investigated as an enabling platform for multimodal endoscopy. This approach offers unparalleled miniaturization, design flexibility, and alignment precision of micro‐optics and actuators. In particular, the design, fabrication, and characterization of a monolithically 3D nano‐printed bistable microlens actuator are discussed. Bistability allows the microlens to switch between two stable positions, thereby changing the focus distance and numerical aperture. The actuator features two coils with opposing current directions, which create a magnetic field gradient around a polymer micro‐magnet. This configuration allows for robust switching between stable positions with an average axial distance of 168.3 ± 7.3 µm. Experiments conducted to ascertain the optical characterization of the actuator demonstrate its capacity to transition between different optical modes. The beam widths are measured to be in the range of 4.1 ± 0.2 µm in the high‐resolution mode and 11.3 ± 1.1 µm in the extended depth of focus mode.