Transparent and Optical Product

Plastic s main disadvantages are its lower scratch resistance and, in some systems, comparative intolerance to severe temperature fluctuations. Even if plastic does have less temperature tolerance than glass, most optical systems do not operate in ambient temperatures beyond the thermal limits of plastics or the human body. 

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This concept has been known for over a century. Expressed as Brewster s Constant law, it states that the index of refraction in a strained material becomes directional, and the change of the index is proportional to the magnitude of the stress (or strain) present. Therefore, a polarized beam in the clear plastic splits into two wave fronts in the X and Y directions that contain vibrations oriented along the directions of principal stresses. An analyzing filter passes only vibrations parallel to its own transmitting plane (Chapter 4, TRANSPARENT AND OPTICAL PRODUCT, Polarized Lighting). 

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