Physics Colloquium - Friday, October 23rd, 2009, 4:00 P.M.

Amy Sullivan
Department of Physics and Astronomy
Agnes Scott College

Measurements of three-dimensional (3D) changes in index of refraction are important for material characterization of photopolymers, glass and other optical materials as well as for characterization of fabricated structures such as waveguides in 3D integrated optics systems. I will discuss an imaging system capable of measuring deeply-buried, weak, fabricated index structures. High-fidelity cross sections of these weak index structures are constructed by replicating the structure to be measured to form a diffraction grating. The coherent addition of scattering from each of these objects increases the sensitivity of the imaging system. Measurements are made in the far field, without the use of lenses, which considerably simplifies the experimental set up and allows for imaging through thick samples. These measurements help in the development of new integrated optical devices as well as leading us to a better understanding of how light sensitive materials behave under a variety of illumination conditions.