Phase plate and fabrication method for color-separated laser backlight in display systems

Abstract

According to examples, a method for phase plate fabrication may be described herein. The method may include providing an interferometer configuration to generate a hologram of a plurality of pinholes. In some examples, the interferometer configuration includes a substrate for photopolymer attachment, a photopolymer having a predetermined thickness, and an exposure mask with a plurality of pinholes. The method may also include exposing the photopolymer with collimated light, via a laser source, through the exposure mask with a plurality of pinholes, wherein the collimated light passes through the exposure mask itself to create a collimated beam, and the plurality of pinholes of the exposure mask to create a spherical wavefront. The collimated beam and the spherical wavefront may help generate the hologram on the photopolymer for use as a phase plate for improved light transmissivity in display systems.

1 . A method for phase plate fabrication, comprising:
 providing an interferometer configuration to generate a hologram of a plurality of pinholes, wherein the interferometer configuration comprises at least a photopolymer and an exposure mask;   exposing the photopolymer to collimated light through the exposure mask with a plurality of pinholes, by passing the collimated light through:
 the exposure mask to create a collimated beam; and 
 the plurality of pinholes to create a spherical wavefront, wherein the collimated beam and the spherical wavefront generate the hologram of the plurality of pinholes; and 
   iteratively shifting pinhole placement for additional wavelengths to repeat exposure of the photopolymer to the collimated light.   
     
     
         2 . The method of  claim 1 , wherein the interferometer configuration comprises:
 a substrate for photopolymer attachment;   the photopolymer having a predetermined thickness; and   the exposure mask with the plurality of pinholes;   
     
     
         3 . The method of  claim 1 , wherein the collimated light is laser light. 
     
     
         4 . The method of  claim 1 , wherein the plurality of pinholes in the exposure mask have a periodic structure. 
     
     
         5 . The method of  claim 4 , wherein any two pinholes of the plurality of pinholes have about 18 micrometer separation. 
     
     
         6 . The method of  claim 1 , wherein each of the plurality of pinholes has about 1 micrometer diameter. 
     
     
         7 . The method of  claim 1 , further comprising:
 selecting a placement of the photopolymer between 100 micrometers and 200 micrometers away from a Talbot self-imaging plane generated by the exposure mask.   
     
     
         8 . The method of  claim 7 , further comprising:
 adding a random phase to at least a portion of the plurality of pinholes in the exposure mask; or   randomizing a location of at least a portion of the pinholes in the exposure mask.   
     
     
         9 . The method of  claim 1 , wherein the interferometer configuration comprises at least two exposure masks. 
     
     
         10 . A method for configuring an exposure mask, comprising:
 determining a size of an exposure mask with a plurality of pinholes for phase plate fabrication;   determining a relative transmission for the mask region relative to the pinholes;   determining a size and location for the plurality of pinholes within the exposure mask based on the relative transmission; and   fabricating the exposure mask with the plurality of pinholes.   
     
     
         11 . The method of  claim 10 , further comprising:
 determining the relative transmission using the following expression:   
       
         
           
             
               T 
               = 
               
                 
                   
                     π 
                     ⁢ 
                     
                       r 
                       2 
                     
                   
                   
                     p 
                     2 
                   
                 
                 = 
                 
                   0.4 
                   % 
                 
               
             
           
         
       
       wherein T is the relative transmission between the exposure mask and the plurality of pinholes, p is a distance between each of the plurality of pinholes, and r is a radius of each pinhole. 
     
     
         12 . The method of  claim 10 , wherein the plurality of pinholes in the exposure mask have a periodic structure. 
     
     
         13 . The method of  claim 12 , wherein any two pinholes of the plurality of pinholes have about 18 micrometer separation. 
     
     
         14 . The method of  claim 10 , wherein each of the plurality of pinholes has about 1 micrometer diameter. 
     
     
         15 . The method of  claim 10 , further comprising:
 adding a random phase to at least a portion of the plurality of pinholes in the exposure mask.   
     
     
         16 . The method of  claim 10 , further comprising:
 randomizing a location of at least a portion of the pinholes in the exposure mask.   
     
     
         17 . An interferometer configuration for phase plate fabrication, the interferometer configuration comprising:
 a substrate;   a photopolymer having a predetermined thickness attached to the substrate; and   an exposure mask with a plurality of pinholes to expose the photopolymer to collimated light by passing the collimated light through:
 the exposure mask to create a collimated beam; and 
 the plurality of pinholes to create a spherical wavefront, wherein the collimated beam and the spherical wavefront generate the hologram of the plurality of pinholes. 
   iteratively shifting pinhole placement for additional wavelengths to repeat exposure of the photopolymer to the collimated light.   
     
     
         18 . The interferometer configuration of  claim 17 , wherein pinhole placement is iteratively shifted for additional wavelengths to repeat exposure of the photopolymer to the collimated light. 
     
     
         19 . The interferometer configuration of  claim 17 , wherein the plurality of pinholes in the exposure mask have a periodic structure. 
     
     
         20 . The interferometer configuration of  claim 17 , wherein the photopolymer is placed between 100 micrometers and 200 micrometers away from a Talbot self-imaging plane generated by the exposure mask.