Hybrid polarizer

Abstract

A hybrid polarizer includes an absorbing element having a first major surface and a second major surface. The hybrid polarizer also includes a first birefringent reflective polarizer disposed on the first major surface of the absorbing element, the first birefringent reflective polarizer having a first pass axis and a first block axis. The hybrid polarizer further includes a second birefringent reflective polarizer disposed on the second major surface of the absorbing element, the second reflective polarizer having a second pass axis and a second block axis.

1 . A hybrid polarizer, comprising:
 an absorbing element having a first major surface and a second major surface, wherein the absorbing element comprises a light absorbing material having an average absorptance of no more than 40% over the desired wavelength range;   a first nearly uniaxial birefringent reflective polarizer disposed on the first major surface of the absorbing element, the first nearly uniaxial birefringent reflective polarizer having a first pass axis and a first block axis; and   a second birefringent reflective polarizer disposed on the second major surface of the absorbing element, the second reflective polarizer having a second pass axis and a second block axis.   
     
     
         2 . The polarizer of  claim 1 , wherein the first and second reflective polarizers each have a reflectivity for light polarized along the first and second block axes that is from about 90% to about 99%. 
     
     
         3 . The polarizer of  claim 1 , wherein the first and second pass axes are aligned to within about +/−1 degrees. 
     
     
         4 . The polarizer of  claim 1 , wherein at least one of the first and second reflective polarizers comprises a plurality of layers characterized by a varying optical thickness. 
     
     
         5 . The polarizer of  claim 1 , wherein the first reflective polarizer has a refractive index difference for light polarized along the first pass axis and light polarized along a thickness direction of the first reflective polarizer that is about 0.02 or less at 633 nm. 
     
     
         6 . The polarizer of  claim 1 , wherein the second reflective polarizer is nearly uniaxial. 
     
     
         7 . The polarizer of  claim 1 , further comprising an additional absorbing element disposed on the first or second reflective polarizer. 
     
     
         8 . The polarizer of  claim 1 , wherein a transmission spectrum of the first reflective polarizer is not the same as the transmission spectrum of the second reflective polarizer.