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Understanding Polarised Light

PostPosted: Wed May 04, 2016 9:13 am
by Karl Klavon
The following was taken from an article published by BFW SALTWATER GUIDING SERVICE: Understanding Polarized Light : Recent research show’s that many fish sense polarized light, human’s do not have the ability to separate polarized from regular light. Regular light= vibrate’s in all direction’s perpendicular to it’s direction of travel. Polarized light however, vibrate’s in only one plane. When light is reflected off many non metallic surface’s, including the ocean surface, it is polarized to some degree. This explain’s how polarized sunglasses work: they block out the horizontally reflected polarized component of light from the ocean surface which cause’s most of the glare but permit the vertically reflected component to pass through.

It is not fully understood why some fish have the ability to sense polarized light, but there are some interesting possibilities, being able to detect polarized light might help fish in their migration’s and ability to swim closely with other’s of the same species. The ability to sense polarized light must certainly be related to the fact that when light is reflected off surface’s, eg bait-fish scale’s, it is polarized. Fish that can detect polarized light have an advantage in finding food, polarizing vision can also enhance the contrast between almost transparent prey, and the background, making the prey easier to see. Another conjecture is that having polarizing vision can let fish see object’s that are farther away — perhaps three times the distance — as fish without this ability.

If this speculation is correct, it may answer the question why some fish can feed under very low-light condition’s, and there is more polarized light at dawn and dusk, which might explain why some fish such as striped bass, seem to feed more aggressively at these times of day. If the ability to sense polarized light help’s fish to find food, then it follow’s that lures-flies that reflect polarized light should be more attractive to such fish. There are many artificial material’s that simulate fish scale’s and various tinsel’s that claim to be excellent reflector’s of polarized light.