Monolithically 3D nano-printed mm-scale lens actuator for dynamic focus control in optical systems

TL;DR

This paper presents a novel monolithically 3D nano-printed lens actuator with large aperture and high robustness, enabling dynamic focus control in miniaturized optical systems for biomedical imaging.

Contribution

It introduces a 3D nano-printed, monolithic lens actuator with integrated optical and mechanical components, optimized for remote focusing in compact imaging devices.

Findings

Achieves 200 um displacement range with high mechanical robustness

Operates at resonant frequencies over 300 Hz

Demonstrates advantages over conventional MEMS actuators

Abstract

Three-dimensional (3D) nano-printing via two-photon polymerization offers unparalleled design flexibility and precision, thereby enabling rapid prototyping of advanced micro-optical elements and systems, including hybrid achromats, diffractive and flat optics, millimeter-sized lenses, fiber-optic sensor heads, and photonic waveguides. These elements have found important applications in endomicroscopy and biomedical imaging. The potential of this versatile tool for monolithic manufacturing of dynamic micro-opto-electro-mechanical systems (MOEMS), however, has not yet been sufficiently explored. This work introduces a 3D nano-printed lens actuator with a large optical aperture, optimized for remote focusing in miniaturized imaging systems. The device integrates ortho-planar linear motion springs, a self-aligned sintered micro-magnet, and a monolithic lens, actuated by dual micro-coils for uniaxial motion. The use of 3D nano-printing allows complete design freedom for the integrated optical lens, while the monolithic fabrication ensures inherent alignment of the lens with the mechanical elements. With a lens diameter of 1.4 mm and a compact footprint of 5.74 mm, it achieves high mechanical robustness at resonant frequencies exceeding 300 Hz while still providing large a displacement range of 200 um (+- 100 um). A comprehensive analysis of optical and mechanical performance, including the effects of coil temperature and polymer viscoelasticity, demonstrates its advantages over conventional MEMS actuators, showcasing its potential for next-generation imaging applications.