Hybrid Aspherical Liquid-Tunable Optical Systems

• Applicant: Professor Dr. Caglar Ataman
• Subject Area: Microsystems ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Polymer Materials
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 387039910

In contrast to the immense progress made in software and electronics, optical system design and implementation essentially follows the traditional methods, predominantly due the ongoing reliance on conventional optical components. HALOs long term vision is to transform optical system design by providing a systematic method to design and manufacture sophisticated optical components capable of effective aberration control without resorting to complex multi-element designs. Specifically, HALO aims to develop a novel liquid-tunable, achromatic and aspherical lens driven by an integrated electrostatic actuator and demonstrate its versatility through an innovative imaging system. Compared to conventional imaging systems that require numerous lenses to control aberrations, the HALO system will comprise a single tunable lens and an image sensor. This single lens will feature a tunable aspherical refractive surface and a diffractive surface in order to control spherical and chromatic aberrations over a large focal length range, respectively. By combining this novel component with state-of-the-art image processing techniques, HALO aims to develop a versatile imaging technology both in terms of system design and its practical implementation, such that its potential impact is maximized. HALOs success will rest on the following pillars of scientific and technical achievements:– A reliable method to design spherical and chromatic aberration-free tunable lenses.– Development of an on-chip actuator monolithically integrated with the tunable-lens – A robust and high-yield fabrication process for monolithic wafer-level manufacturing– A single-lens imaging system with real-time numerical field-curvature correction through focal length tuningIn HALO, we aim to develop a new approach to tunable lens design to address all these issues following an integrated approach, enabled by state-of-the-art microfabrication techniques. This choice follows the objective of realizing the above-listed innovations in a device of real practical use. Endoscopic imaging and advanced imaging systems for consumer electronics are envisioned to be primary focus of the HALO lens. By transferring as much hardware complexity as possible into efficient computational methods, HALO aims to attain state-of-the-art imaging performance with a single lens. Since field curvature correction is the foremost source of such complexity for modern imaging systems, we will exploit the unique aberration-free focal length tuning capability of the HALO lens to dynamically adapt the focal plane during exposure, such that separate images with optimum focus at different radial positions are recorded. A digital combination of these images will provide an image without field-curvature. The imaging system concept to be designed around the tunable lens will act as a demonstrator, showcasing the versatility that such a component would bring into optical system design.

• DFG Programme: Research Grants