Three-dimensional ocean chlorophyll distributions from underwater serial-sectioned fluorescence images.

An underwater optical serial-sectioning technique is developed to measure in situ three-dimensional distributions of biological particles. The technique involves scanning of a thin plane of laser light through a range of distances parallel to the imaging plane of a digital CCD camera. Images of induced fluorescence in the sequentially illuminated planes are recorded. An inverse method is then used to reconstruct three-dimensional chlorophyll a distributions from the plane images. Computer simulations of the image formation and reconstruction process indicate that the underwater optical serialsectioning technique is practical for in situ determination and analysis of chlorophyll a microstructures for concentrations as low as 0.1 mg of chlorophyll a per cubic meter in 1--m(3) water volumes.