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Tinted Lens 79

Fig. 7.11: Polaroid lens allows only useful vertical light waves

Fig. 7.12: Principle of polarized lens is best illustrated by observing Venetian blinds
which blocks light at certain angles, while allows light to transmit through it at certain
other angle

APPLICATION OF POLARIZED LENSES

Polarizing filters are created by stretching sheets of polyvinyl alcohol (PVA)
so that its molecules align in long directional chains. The PVA is then passed
through an iodine solution where the light absorbing iodine molecules
attach to the molecular chains forming the microscopic blinds. The film so
prepared is sandwiched in the lens. The back surface of the lens is cast first
and the precurved Polaroid film is placed on the cast part and then liquid

material is injected over. Polarizing filters are aligned 90° to the angle of
the polarized light.