Angular domain imaging in scattering media with background subtraction, multi-spectral sources, and fluorescence

Optical imaging within scattering media is difficult because the highly scattered light obscures the structure. Angular Domain Imaging is an optical tomography technique using angular filters (Spatiofrequency filters and collimating arrays) to reject scattered light and accept non-scattered light. Two techniques are explored: direct-illumination through large scattering medium (~5cm), and indirect-illumination through shallow media (~1-2mm) with fluorescence sources. Using enhancement techniques, such as background scattered light estimation, improve images quality and contrast ratio, and the system’s scattering limit. Multi-spectrum ADI can provide new optical and chemical information of the sample, but filtration and wavelength selection are difficult. Monte Carlo simulations were used to study the effectiveness of incorporating ADI into FI applications and to analyze the two angular filters’ performance in fluorescence shallow scattering. R6G and fluorescence slides emulate collagen layers in tissue in experiments validating the simulation results and demonstrating the effectiveness of ADI in FI.