Experimentally determined optical properties of goldfish cones and rods.

The optical properties of goldfish photoreceptors were evaluated using the special microscope-microspectrophotometer divice. Mode patterns transmitted were identified for both natural and reverse path illumination. Photomechanical changes with adaptive state could be identified. Complex mode interactive phenomena and cross-coupling of energy were observed. These are related to the fact that there are double cones and apposition or near apposition of neighboring receptors in this species. The directionality of individual cones and rods was quantified by making use of the principle of reversibility of light path. Radiation patterns were recorded and analyzed on a computer controlled microdensitometer. Individual cones and rods were shown to exhibit marked directionality. Light collection properites of cones were strikingly evident.