Transparent anti-reflective article and method of fabricating same

Abstract

A transparent anti-reflective article includes a transparent substrate having a first refractive index and a first surface. An anti-reflective layer is formed within the first surface of the transparent substrate through use of one of nanosphere lithography, deep ultra-violet photolithography, electron beam lithography, and nano-imprinting. The anti-reflective layer includes a subwavelength nano-structured second surface including a plurality of protuberances. Such protuberances have a predetermined maximum distance between adjacent protuberances and a predetermined height for a given wavelength such that the anti-reflective layer includes a second refractive index lower than the first refractive index to minimize light diffraction and random scattering therethrough. The predetermined height is approximately equal to a quarter of the given wavelength divided by the second refractive index.

1 . A transparent anti-reflective article comprising:
 a transparent substrate having a first refractive index and a first surface, wherein an anti-reflective layer is formed within the first surface of the transparent substrate, the anti-reflective layer including a subwavelength nano-structured second surface including a plurality of protuberances having a predetermined maximum distance between adjacent protuberances and a predetermined height for a given wavelength such that the anti-reflective layer includes a second refractive index lower than the first refractive index to minimize light diffraction and random scattering therethrough, wherein the anti-reflective layer is formed through use of one of one of nanosphere lithography, deep ultra-violet photolithography, electron beam lithography, and nano-imprinting.   
     
     
         2 . The article of  claim 1 , wherein the predetermined height is approximately equal to a quarter of the given wavelength divided by the second refractive index. 
     
     
         3 . The article of  claim 1 , wherein the second refractive index is approximately equal to the square root of the first refractive index. 
     
     
         4 . The article of  claim 1 , wherein the predetermined maximum distance between adjacent protuberances is defined as:
   Λ<λ/[max( n   3   ,n   1 )+ n   3  sin(α)],   wherein λ represents an incident wavelength and Λ represents the distance between two adjacent protuberances thereof,   wherein argument n 1  represents the first refractive index and argument n 3  represents a third refractive index of a medium above the anti-reflective second surface, and   wherein max represents the maximum of the arguments.   
     
     
         5 . The article of  claim 1 , wherein the predetermined maximum distance between adjacent protuberances is between about 50 and 500 nm. 
     
     
         6 . The article of  claim 1 , wherein the transparent substrate comprises at least one of the following components: glass, high density polyethylene, polypropylene, polymeric material, polyvinyl chloride, quartz, transparent dielectric, or diamond, or a mixture thereof. 
     
     
         7 . The article of  claim 1 , wherein the transparent substrate is a display screen, wherein the display screen includes one of a cell phone screen, a computer monitor screen, a television monitor screen, and a liquid crystal display (LCD) screen. 
     
     
         8 . The article of  claim 1 , further comprising a hydrophobic material disposed on the subwavelength nano-structured second surface, the hydrophobic material having a predetermined thickness and a predetermined hydrophobicity for self-cleaning and repelling from fluids thereon. 
     
     
         9 . The article of  claim 8 , wherein the hydrophobic material comprises polytetrafluoroethylene, silicone, paraffin wax, isotactic polypropylene, or polystyrene, or a mixture thereof. 
     
     
         10 . An anti-reflective display screen comprising:
 a transparent display panel having a first refractive index and a viewing first surface, wherein the first surface is modified to a subwavelength nano-structured second surface to define an anti-reflective layer formed within the first surface of the transparent display panel such that the transparent display panel and the anti-reflective layer are of the same material, the subwavelength nano-structured second surface including a plurality of protuberances having a predetermined maximum distance between adjacent protuberances and a predetermined height for a given wavelength such that the anti-reflective layer includes a second refractive index approximately equal to the square root of the first refractive index to minimize light diffraction and random scattering therethrough, wherein the predetermined height is approximately equal to a quarter of the given wavelength divided by the second refractive index, and wherein the first surface is modified to define the anti-reflective layer through use of one of nanosphere lithography, deep ultra-violet photolithography, electron beam lithography, and nano-imprinting.   
     
     
         11 . The display screen of  claim 10 , wherein the display screen includes one of a cell phone screen, a computer monitor screen, a television monitor screen, and a liquid crystal display (LCD) screen. 
     
     
         12 . The display screen of  claim 10 , wherein the predetermined maximum distance between adjacent protuberances is defined as:
   Λ<λ/[max( n   3   ,n   1 )+ n   3  sin(α)],   wherein λ represents an incident wavelength and Λ represents the distance between two adjacent protuberances thereof,   wherein argument n 1  represents the first refractive index and argument n 3  represents a third refractive index of a medium above the anti-reflective second surface, and   wherein max represents the maximum of the arguments.   
     
     
         13 . The article of  claim 10 , further comprising a hydrophobic material disposed on the subwavelength nano-structured second surface, the hydrophobic material having a predetermined thickness and a predetermined hydrophobicity for self-cleaning and repelling from fluids thereon. 
     
     
         14 . A method of fabricating an anti-reflective optically transparent structure, the method comprising:
 providing an optically transparent substrate having a first refractive index and a first surface; and   forming an anti-reflective layer within the first surface of the transparent substrate which includes forming a nano-scale pattern within the first surface defining a subwavelength nano-structured second surface of the anti-reflective layer including a plurality of protuberances having a predetermined maximum distance between adjacent protuberances and a predetermined height for a given wavelength such that the anti-reflective layer includes a second refractive index lower than the first refractive index to minimize light diffraction and random scattering therethrough, wherein the predetermined height is approximately equal to a quarter of the given wavelength divided by the second refractive index, and wherein one of nanosphere lithography, deep ultra-violet photolithography, electron beam lithography, and nano-imprinting is used to form the anti-reflective layer.   
     
     
         15 . The method of  claim 14 , wherein the second refractive index is approximately equal to the square root of the first refractive index. 
     
     
         16 . The method of  claim 14 , wherein the predetermined maximum distance between adjacent protuberances is defined as:
   Λ<λ/[max( n   3   ,n   1 )+ n   3  sin(α)],   wherein λ represents an incident wavelength and Λ represents the distance between two adjacent protuberances thereof,   wherein argument n 1  represents the first refractive index and argument n 3  represents a third refractive index of a medium above the anti-reflective second surface, and   wherein max represents the maximum of the arguments.   
     
     
         17 . The method of  claim 14 , wherein the predetermined maximum distance between adjacent protuberances is between about 50 and 500 nm. 
     
     
         18 . The method of  claim 14 , wherein the transparent substrate comprises at least one of the following components: glass, high density polyethylene, polypropylene, polymeric material, polyvinyl chloride, quartz, transparent dielectric, or diamond, or a mixture thereof. 
     
     
         19 . The method of  claim 14 , wherein the transparent substrate is a display screen, wherein the display screen includes one of a cell phone screen, a computer monitor screen, a television monitor screen, and a liquid crystal display (LCD) screen. 
     
     
         20 . The method of  claim 14 , further comprising:
 coating the subwavelength nano-structured second surface with a layer of hydrophobic material having a predetermined hydrophobicity.