A polarized laser backlight using a zero-zero-birefringence polymer for liquid crystal displays

We have demonstrated a polarized laser backlight for liquid crystal displays and have investigated its basic polarization properties. To maintain the state of polarization of light propagating through the light-guide plate (LGP) of the backlight, we fabricated the LGP by injection molding of a zero-zero-birefringence polymer, poly(methyl methacrylate-co-2,2,2-trifluoroethyl methacrylate-co-benzyl methacrylate) (52: 42: 6 by mass) that is free of both orientational and photoelastic birefringence. The degree of polarization of light from the resulting backlight (average: 92. 4%) was much higher than that from a backlight with a polycarbonate LGP (average: 8. 0%) in the defined effective range of the backlight. A laser speckle pattern was observed but the speckle contrast on the output surface of the backlight was reduced from 68 to 10% by vibrating a diffuser sheet situated in front of the output surface of the LGP. We also manufactured a white surface light source [chromaticity (value: x, y) = (0:310, 0:314)] by mixing the outputs from three primary-color-emitting lasers in the backlight.