This paper briefly describes a method of fabricating polymeric optical elements with a new property: an axial birefringence gradient (BRG), and presents the results of an experimental study Of their optical polarization properties. The BRG elements were fabricated from thin films of polyvinyl alcohol (PVA, d= 100-150 mu m) and polyethylene (terephthalate (PET, d= 190 mu m). It is shown that the birefringence gradient Delta n in the middle of the BRG element increases exponentially along the central z axis, with Delta n(max) approximate to 0.02. Increasing the forming temperature of the BRG element from 80 to 90 degrees C improves the linearity of the Delta n=f(z) dependence, even though it is degraded and becomes irregular in the peripheral zone. (C) 2005 Optical Society of America.
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