Polarizational Characteristics of the Underwater World
In qualitative submarine visual observations down to 15 m, Waterman (1954) found that aquatic animals of the photic zone are surrounded by complex polarization patterns. He used a diving helmet and a hand-held polarization analyser, in which the light first passed through a plate of a uniaxial crystal cut perpendicularly to its optical axis, then through a quarter-wave plate and a linearly polarizing filter. The intensity of unpolarized light passing through this polariscope simply decreases. If the incident light is partially linearly polarized, a brightly coloured interference pattern of concentric, broken rings appears in the polariscope, from which the presence of polarization, the Evector direction as well as a rough estimate of the degree of linear polarization p can be deduced. The interruptions of the broken rings occur in orthogonal quadrants, and the axis of one of the pairs of these opposed quadrants is parallel to the E-vector of incident light. Both the intensity of the pattern and the number of concentric rings vary with p. With this polariscope, the E-vector direction could be obtained with an accuracy of about ±3°.
KeywordsChlorophyll Attenuation Retina Refraction Azimuth
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