Sunglasses, polarized

If you have a pair of polarized sunglasses, you are likely to have seen the effects of tempered glass on rear and side windows of cars. The telltale white or gray spot array pattern is an indication of where the cold air jets were located (see Fig. 1.8). 

Apparatus for using a lightbulb and two pairs of polarized sunglasses as a simple polarimeter. 

Optical films for polarized sunglasses, display screens,... 

Minimal transmission occurs when the plane of polarization of the light is perpendicular to that of the analyzer through which it is viewed. This effect can be demonstrated using two pairs of polarized sunglasses as shown in Figure 10.5. If the plane of polarization is rotated to the right, the isomer is said to be dextrorotatory and is labeled d if it is rotated to the left, the isomer is called levorolatory and labeled /. Enantiomers always rotate the light by the same amount, but in opposite directions. Thus, in an equimolar mixture of both enantiomers, called a racemic mixture, the net rotation is zero. 

A special thin-film transistor (TFT) display with rotated polarization is used for the ProViuOMirror. The polarization is oriented in such a way that the use of polarized sunglasses is possible (see Fig. 5). 

Seventy-five years later, in 1938, Edwin Land invented the sheet polarizer, called H-film, that has been industrialized as the Polaroid filter. Attached to the windows of ships and trains these filters can act as blinds, and they also have been widely used in polarized sunglasses. There was a time when Polaroid filters were considered as antiglare systems for large-scale windshield and headlights of cars [1]. 

Figure 10.5 Two pairs of polarized sunglasses, (a) When two polarized lenses overlap with their planes of polarization parallel to each other, light is transmitted, (b) When one pair is rotated so that its plane of polarization is perpendicular to the other, no light is transmitted through the overlapped lenses.

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