| PhD Seminar

Name of the Speaker: Ms. Susan Thomas (EE20D751)
Guide: Dr. Shanti Bhattacharya
Co-Guide: Dr. Francesco Ferranti
Venue: ESB-244 (Seminar Hall)
Online meeting link: https://meet.google.com/pdb-pbqq-fmw
Date/Time: 23rd May 2025 (Friday), 3 PM
Title: Aberration correction with metaoptics in microendoscopy imaging

Abstract :

Microendoscopy systems capable of high-resolution imaging are under active development for applications in image-guided surgery and disease diagnosis. State-of-the-art commercial endoscopes use fiber bundles to illuminate the tissue, collect the scattered light, and transmit it to the camera for image formation. High-resolution imaging requires a denser optical fiber bundle, increasing the complexity and cost of the system. Also, the multicore structure and crosstalk between cores cause pixelation artifacts that compromise the image quality in fiber bundle endoscopy. Scanning fiber endoscopy systems are a promising alternative as they can be designed with a single fiber alongside micro-objective lenses. However, these systems face a significant challenge of off-axis aberration, a critical factor affecting resolution, especially at the extremities of the imaging field. Existing aberration correction methods, such as bulky refractive lens triplets or custom-fabricated GRIN lenses, add to the alignment complexity of the optical assembly. In response to this challenge, we propose a novel design integrating a metasurface with the GRIN micro-objective to address optical aberrations during beam scan.

In this seminar, we present a comprehensive design workflow of a metasurface to correct off-axis aberrations for a scanning fiber endoscopy probe. The design modeling involves extracting electromagnetic fields from nanoscale structures and propagating them through macroscale optics, utilizing the interoperability between the ray tracing and electromagnetic simulations.

We tested the hybrid metasurface-GRIN lens system in a benchtop endoscopy setup, and the results showing improvement with the addition of metasurface will be presented. We validated system performance using reflectance imaging of a resolution target and explored preliminary reflectance and fluorescence imaging of biological samples.