Reflection Matrix Method for Controlling Light After Reflection From a Diffuse Scattering Surface

This research focuses on reflective inverse diffusion, which was a proof-of-concept experiment that used phase modulation to shape the wavefront of a laser causing it to refocus after reflection from a rough surface. By refocusing the light, reflective inverse diffusion has the potential to eliminate the complex radiometric model of indirect photography by creating a virtual light source at the first diffuse reflector that satisfies the line-of-sight requirement of dual photography. However, the initial reflective inverse diffusion experiments provided no mathematical background and were conducted under the premise that the process operated similarly to transmissive inverse diffusion. In this research, diffraction modeling of the reflective inverse diffusion experiments led to the development of Fourier transform-based simulations. Simulations and experimentation were used to develop reflection matrix methods that determine the proper phase modulation to refocus light after reflection to any location in the observation plane. These techniques provide a new method for controlled illumination of an occluded scene that can be used in conjunction with dual photography. This document provides the mathematical background for reflective inverse diffusion, the reflection matrix methods for phase modulation, and describes the simulations and experiments conducted