Methods for Compensating for Optical Surface Nonuniformity

Abstract

Systems and methods for compensating for nonuniform surface topography features in accordance with various embodiments of the invention are illustrated. One embodiment includes a method for manufacturing waveguide cells, the method including providing a waveguide including first and second substrates and a layer of optical recording material, and applying a surface forming process to at least one external surface of the first and second substrates. In another embodiment, applying the surface forming process includes applying a forming material coating to the at least one external surface, providing a forming element having a forming surface, bringing the forming element in physical contact with the forming material coating, curing the forming material coating while it is in contact with the forming element, and releasing the forming material coating from the forming element.

What is claimed is: 
     
         1 . A method for manufacturing waveguide cells, the method comprising:
 providing a waveguide comprising first and second substrates and a layer of optical recording material; and   applying a surface forming process to at least one external surface of said first and second substrates.   
     
     
         2 . The method of  claim 1 , wherein applying said surface forming process comprises:
 applying a forming material coating to said at least one external surface;   providing a forming element having a forming surface;   bringing said forming element in physical contact with said forming material coating;   curing said forming material coating while it is in contact with said forming element; and   releasing said forming material coating from said forming element.   
     
     
         3 . The method of  claim 1 , wherein said surface forming process provides surface planarization said at least one external surface. 
     
     
         4 . The method of  claim 2 , wherein applying said surface forming process further comprises depositing at least one of a release layer or a hard coat layer. 
     
     
         5 . The method of  claim 2 , wherein curing said forming material coating comprises applying UV curing radiation via a curing configuration selected from the group consisting of: one or more UV sources distributed above said forming material coating, a fixture comprising UV sources spatially distributed around the waveguide, and one or more UV sources coupled into an internal reflection path within at least one of said forming element or said waveguide. 
     
     
         6 . The method of  claim 2 , wherein curing said forming material coating comprises a curing configuration selected from the group consisting of: applying radiation having more than one wavelength, applying UV radiation having more than one wavelength within the UV spectrum, applying a thermal process, applying pressure, immersing said forming material coating in a vacuum, immersing said forming material coating in a gas, immersing said forming material coating in a liquid, applying radiation having a wavelength within the visible spectrum, applying radiation having a wavelength within the infrared spectrum, and exposing said forming material coating to a humid atmosphere. 
     
     
         7 . The method of  claim 2 , wherein said forming material coating comprises a material selected from the group consisting of: photoresists, resins, polymers, thermosets, thermoplastic polymers, polyepoxies, polyamides, low viscosity planarization materials, materials with viscosity between 10 and 15 cps at 20° C., materials with viscosity below 2 cps at 20° C., and ethylene glycol diacrylate. 
     
     
         8 . The method of  claim 2 , wherein said release layer is a fluorocarbon silylating agent. 
     
     
         9 . The method of  claim 4 , wherein said forming surface of said forming element has a surface characteristic for compensating for shrinkage of said forming material coating. 
     
     
         10 . The method of  claim 2 , further comprising correcting a wedge characteristic of the forming material coating after completion of said surface forming process. 
     
     
         11 . The method of  claim 2 , where said first substrate is curved; and said forming element surface has a curvature matching the curvature of said first substrate. 
     
     
         12 . The method of  claim 2 , wherein said forming surface of said forming element has a degree of planarization less than 98%. 
     
     
         13 . The method of  claim 1 , wherein said first substrate is a plastic. 
     
     
         14 . The method of  claim 1 , wherein said substrates have a birefringence calculated to provide smoothing of non-uniformity after a predefined number of TIR beam reflections. 
     
     
         15 . The method of  claim 2 , further comprising employing an apparatus for monitoring at least one selected from the group of thickness, composition, and uniformity of said forming material during deposition. 
     
     
         16 . The method of  claim 1 , wherein providing said waveguide comprises:
 providing said first substrate;   depositing said layer of optical recording material onto said first substrate using at least one deposition head, wherein said optical recording material deposited over a grating region is formulated to achieve a predefined grating characteristic selected from the group consisting of: refractive index modulation, refractive index, birefringence, liquid crystal director alignment, grating layer thickness, and a spatial variation of said characteristic;   providing said second substrate;   
       placing said second substrate onto said deposited layer of optical recording material; and
 laminating said first substrate, said layer of optical recording material, and said second substrate. 
 
     
     
         17 . The method of  claim 16 , wherein providing said waveguide further comprises depositing at least one of release layer or a hard coat layer using said at least one deposition head. 
     
     
         18 . The method of  claim 2 , wherein said forming element is an optical flat, a refractive optical element, or an optical element with at least one optical surface providing optical power. 
     
     
         19 . The method of  claim 2 , wherein said forming element is supported by a substrate providing an optical path from a light source for curing. 
     
     
         20 . The method of  claim 1 , wherein said layer of optical recording material comprises a polymer dispersed liquid crystal mixture.