Second Harmonic Generation and Corneal Collagen

Research Overview

My research focuses on non-linear optics for bio-medical applications. In this research we use second harmonic generation microscopy to explore the mechanical properties of collagenous tissues as well as to examine the fibrillogenesis process of these tissues. We are collaborating with Prof. Jeff Roburti's group, from the department of mechanical engineering at Northeastern University. We are using an in-house-built bio-reactor which was tailored to fit the stage of our state-of-the-art, multimodal Keck microscope. The bio-reactor is being used to apply load to the sample while it is being imaged using our microscope.

SHG microscopy is also being used to characterize the organizational structure of corneal collagen. The organizational information is of very high importance for the understanding and characterization of the strength of the chemical boding between sheets of collagen in corneal tissues. SHG microscopy has the ability to perform sectioning of the examined tissue, and by using it we are hoping to improve on other methods that were previously used to explore the orientation of the fibers in the sheets. The x-ray based methods used by others look at the sample as a whole and cannot provide any information about the inter-sheet bonding. The strength of inter-sheet bonding is very important since it controls the progression of Kateraconus. We are hoping to shed more light on understanding the progression of the disease and are looking to collaborate with Ophthalmologists using SHG.

We also perform theoretical research to explore the microscopic nature of SHG emission. We are using the finite-difference time-domain (FDTD) to simulate the emission signature of SHG waves. We are hoping to be able the derive micro-structural information in such as the length of collagen fibers by the measuring the intensity of the SHG image.

Optical Science Laboratory

This research project is part of the work at the Optical Science Laboratory of Chuck DiMarzio in the Department of Electrical and Computer Engineering at Northeastern University. For other projects see Optical Science Lab Research Page.

Publications and Patent
  • Yair Mega, Mike Robitaille, Ramin Zareian, James McLean, Jeffrey Ruberti, and Charles DiMarzio, "Quantification of lamellar orientation in corneal collagen using Second Harmonic Generation images". To be printed in Optics Letters 2012 summer
  • Yair Mega, Title of Invention: Image processing method for quantitative evaluation of the orientation of wavey and crimpy fibers from an image

Last update 13 July 2012