Beyond day glow highlighters and psychedelic black light posters, it has been estimated that fluorescence is a property exhibited by 20% of objects. When a fluorescent material is illuminated with a short wavelength light, it re-emits light at a longer wavelength isotropically in a similar manner as a Lambertian surface reflects light. We use this property to our advantage in various areas. We designed the Fluorescence Imaging System (FluorIS), based on a consumer camera modified for greatly increased sensitivity to chlorophyll-a fluorescence, and we show high spectral correlation between acquired images and in situ spectrometer measurements. This system greatly facilitates underwater wide field-of-view fluorophore surveying during both night and day, and enables improvements in semi-automated segmentation of live corals in coral reef photographs and juvenile coral surveys. This system was also used to investigate the phenomenon of coral fluorescence in mesophotic reefs which is largely unstudied. Finally, we use fluorescence to reconstruct 3D shape with some of the same techniques as for Lambertian surfaces – even when the surface’s reflectance is highly non-Lambertian.

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