Länk - Man kan detektera polariserat ljus med blotta ögat
Many people find it hard to see Haidinger's brush initially. It is very faint, much more so than generally indicated in illustrations, and, like other stabilized images, tends to appear and disappear. It is most easily seen when it can be made to move. Since it is always positioned on the macula, there is no way to make it move laterally, but it can be made to rotate, by viewing a white surface through a rotating polarizer, or by slowly tilting your head to one side.
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