Patterned polarization converter

Abstract

The present invention provides a patterned polarization converter having multiple domains that can be used to convert input linear polarized light to output light with spatially varying polarization states, including domains that produce linearly polarized light and domains that produce circular polarized light based on the patterning of the domains. A patterned polarization converter having multiple domains may be used in a polarization sensor application capable of detecting the polarization state of input light. The present invention further provides patterned radial and azimuthal polarization converters, which have utility in applications such as optical tweezers. Additionally, patterned polarization converters may be used to fabricate more patterned polarization converters having the same pattern using one-step photoalignment to copy the pattern of an existing patterned polarization converter to an unpatterned photoalignment layer.

1 . A patterned polarization converter, comprising:
 a quarter wave plate; and   a patterned quarter wave plate positioned substantially parallel to the quarter wave plate, wherein the patterned quarter wave plate comprises a first retardation domain corresponding to an optical axis and at least one of another retardation domain corresponding to a different optical axis than the first retardation domain and at least one non-retardation domain.   
     
     
         2 . The patterned polarization converter of  claim 1 , wherein the patterned polarization converter is configured to convert linearly polarized light input into the quarter wave plate to light having spatially varying polarization states output from the patterned quarter wave plate. 
     
     
         3 . The patterned polarization converter of  claim 1 , wherein the patterned polarization converter is configured to convert polarized light input into the patterned quarter wave plate to polarized light output from the quarter wave plate corresponding to an optical axis of the quarter wave plate. 
     
     
         4 . The patterned polarization converter of  claim 1 , wherein at least one of the quarter wave plate and the patterned quarter wave plate is a broad-band quarter wave plate. 
     
     
         5 . The patterned polarization converter of  claim 1 , wherein the patterned quarter wave plate is a liquid crystal cell. 
     
     
         6 . The patterned polarization converter of  claim 5 , wherein the patterned quarter wave plate comprises two electrodes, and the patterned polarization converter further comprises:
 a voltage source connected to the two electrodes of the patterned quarter wave plate for switching retardation domains of the patterned quarter wave plate on and off, and for tuning the retardation domains of the patterned quarter wave plate.   
     
     
         7 . The patterned polarization converter of  claim 1 , wherein domains of the patterned quarter wave plate are configured such that the patterned polarization converter converts linearly polarized light input into the quarter wave plate into at least one of radially and azimuthally polarized light output from the patterned quarter wave plate. 
     
     
         8 . The patterned polarization converter of  claim 1 , wherein the patterned polarization converter is a solid retardation plate comprising a liquid crystal polymer (LCP) film. 
     
     
         9 - 12 . (canceled) 
     
     
         13 . A polarization sensor, comprising:
 a patterned polarization converter configured to convert polarized light input into a patterned quarter wave plate to polarized light output from a quarter wave plate corresponding to an optical axis of the quarter wave plate, wherein the patterned polarization converter further comprises:
 the quarter wave plate; and 
 the patterned quarter wave plate, wherein the patterned quarter wave plate is positioned substantially parallel to the quarter wave plate, and the patterned quarter wave plate comprises a first retardation domain corresponding to an optical axis and at least one of another retardation domain corresponding to a different optical axis than the first retardation domain and at least one non-retardation domain; 
   a linear polarizer, wherein light output from the patterned polarization converter passes through the linear polarizer and has intensity corresponding to the input light and domains of the patterned quarter wave plate; and   a sensor array configured to receive light passed through the linear polarizer.   
     
     
         14 . The polarization sensor of  claim 13 , wherein the sensor array is one of the group consisting of: a CCD (charge-coupled device) sensor array and a CMOS (complementary metal-oxide-semiconductor) sensor array. 
     
     
         15 . The polarization sensor of  claim 13 , wherein the sensor array has at least one pixel corresponding to at least one domain of the patterned polarization converter. 
     
     
         16 . The polarization sensor of  claim 13 , wherein if non-polarized light is input into a plurality of the domains of the patterned quarter wave plate of the patterned polarization converter, the light received at the sensor array corresponding to the plurality of domains has uniform intensity. 
     
     
         17 . A method of making one step multi-domain photoalignment patterns on a photoalignment layer, the method comprising:
 applying the photoalignment layer to a substrate;   providing a patterned polarization converter above and aligned substantially parallel to the photoalignment layer; and   exposing the photoalignment layer through the patterned polarization converter using a linearly polarized light source.   
     
     
         18 . The method of  claim 17 , wherein linearly polarized light provided by the linearly polarized light source becomes linearly polarized light with spatially varying polarization directions after passing through the patterned polarization converter and the linearly polarized light with spatially varying polarization directions exposes the photoalignment layer. 
     
     
         19 . The method of  claim 17 , wherein the exposed photoalignment layer is configured to align liquid crystal or liquid crystal polymer and suitable for use in making additional polarization converters having a pattern similar to the patterned polarization converter.