Improving underwater vision using confocal imaging

Confocal microscopy is a family of techniques that employ patterned illumination and synchronized imaging to create cross-sectional views of biological specimens. In this paper, we adapt confocal imaging to improving visibility underwater by replacing the optical apertures used in microscopy with arrays of video projectors and cameras. In our principal experiment, we show that using one projector and one synchronized camera we can see further through turbid water than is possible using floodlighting. Drawing on experiments reported by us elsewhere, we also show that using multiple projectors and multiple cameras we can selectively image any plane in a partially occluded environment. Among underwater occluders we can potentially disregard this way are coral, fish, and marine snow, but we have not verified this underwater. Finally, we describe a large array of cameras we have built to simulate a single video camera of unusually high resolution and dynamic range. Such arrays might be useful in underwater imaging.