| PhD Seminar

Name of the Speaker: Mr. Jerin Geogy George (EE20D029)
Guide: Dr. Shanti Bhattacharya
Venue: ESB-244 (Seminar Hall)
Online meeting link: https://meet.google.com/fvp-rrdt-nsy
Date/Time: 28th April 2025 (Monday), 4 PM
Title: Meta-optics beam shaping for improved Bessel light sheets

Abstract :

Light sheet microscopy is a relatively new imaging technique that enables rapid volumetric imaging. Unlike traditional microscopy methods, light sheet imaging features an orthogonal geometry between the illumination and collection paths. This configuration makes it suitable for using complex light fields such as Bessel and Airy beams, which offer advantages over conventional Gaussian beams. However, Bessel beams suffer from strong sidelobes, which can degrade image contrast and increase photobleaching.

In this seminar, we present the design and generation of a sidelobe-suppressed Bessel beam (SSBB) to create an improved Bessel light sheet. The SSBB is generated using phase-gradient metasurfaces, which provide a compact and flexible way to implement arbitrary phase functions for shaping light. We discuss the fabrication process using polysilicon metasurfaces for infrared wavelengths and silicon nitride metasurfaces for the visible regime. A comparison of SSBBs and conventional Bessel beams, emphasizing the benefits of sidelobe suppression, along with biological imaging results will be presented.

We also introduce additional strategies to enhance SSBB-based light sheet imaging, including structured illumination and far-field spatial filtering. Finally, we explore the integration of the STED (stimulated emission depletion) principle with zeroth and first-order SSBBs to generate high-resolution “light needles”.