Fluorescence excitation spectroscopic imaging with a tuneable light source and dimensionality reduction using FR-IsoMap

This paper presents an optical system for performing excitation resolved imaging of fluorescent dyes, tissue phantoms and ex vivo tissues. The excitation source was a supercontinuum generated in a highly nonlinear fibre, spectrally filtered using dispersive optics and a movable slit or digital micromirror device. This allowed excitation with multiple spectra, which may be chosen to optimize the fluorescence yield from a particular fluorophore, or to maximize discrimination between multiple labels. As an initial validation, the analysis of fluorescent dye solutions embedded in collagen gels in the presence of scatterers and absorbers by using fixed reference isomap (FR-IsoMap) is presented, followed by initial evaluation with human lung bronchial tissue. The proposed system has potential applications for in vivo fluorescence endoscopy of cancerous tissues through excitation spectral selection and analysis with FR-IsoMap.