Front light devices and methods of fabrication thereof

Abstract

A illumination device comprises a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide. A turning microstructure is disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure comprises a plurality of indentations. A cover is physically coupled to the light guide and disposed over the turning microstructure. An interlayer is between the cover and the light guide, wherein the interlayer physically couples the cover to the light guide. A plurality of open regions is between the interlayer and the plurality of indentations. Various embodiments include methods of coupling the cover to the light guide while preserving open regions between the cover and plurality of indentations.

What is claimed is: 
     
         1 . A illumination device comprising:
 a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide;   a turning microstructure disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure includes a plurality of indentations;   a cover physically coupled to the light guide and disposed over the turning microstructure;   an interlayer between the cover and the light guide, wherein the interlayer physically couples the cover to the light guide; and   a plurality of regions between the interlayer and the plurality of indentations at least partially including a material different from the interlayer.   
     
     
         2 . The illumination device of  claim 1 , wherein the light guide has a first index of refraction and the interlayer has a second index of refraction and the second index of refraction is lower than the first index of refraction. 
     
     
         3 . The illumination device of  claim 1 , wherein the plurality of regions includes a reflective material that lines a surface of the plurality of indentations. 
     
     
         4 . The illumination device of  claim 3 , wherein the reflective material is a metal. 
     
     
         5 . The illumination device of  claim 3 , wherein the reflective material includes a thickness of at least about 50 nm. 
     
     
         6 . The illumination device of  claim 3 , wherein the reflective material includes a thickness of at least about 100 nm. 
     
     
         7 . The illumination device of  claim 3 , wherein the interlayer contacts the reflective material within the plurality of indentations. 
     
     
         8 . The illumination device of  claim 3 , wherein the reflective material fills the plurality of regions. 
     
     
         9 . The illumination device of  claim 1 , wherein the plurality of regions includes a material having an index of refraction substantially close to air. 
     
     
         10 . The illumination device of  claim 1 , wherein the plurality of regions includes a substantially porous material. 
     
     
         11 . The illumination device of  claim 1 , wherein the interlayer does not extend over the plurality of regions, and the material of the regions contacts the cover. 
     
     
         12 . The illumination device of  claim 1 , further comprising a plurality of barriers separating the plurality of regions from the interlayer. 
     
     
         13 . An illumination device comprising:
 a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide;   a turning microstructure disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure includes a plurality of indentations;   a cover physically coupled to the light guide and disposed over the turning microstructure;   a plurality of open regions between the cover and the plurality of indentations;   wherein the light guide has a first index of refraction and the cover has a second index of refraction and the second index of refraction is lower than the first index of refraction.   
     
     
         14 . The illumination device of  claim 13 , wherein the plurality of indentations includes a plurality of V-shaped grooves and the open regions include substantially triangular cross-sections. 
     
     
         15 . The illumination device of  claim 13 , wherein the plurality of indentations includes a plurality of grooves and the open regions include substantially trapezoidal cross-sections. 
     
     
         16 . The illumination device of  claim 13 , wherein the turning microstructure includes a diffraction grating. 
     
     
         17 . The illumination device of  claim 13 , wherein the cover directly contacts about 90% or more surface area of the first side of the light guide. 
     
     
         18 . A method of manufacturing a illumination device comprising:
 providing a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide, said light guide having turning microstructure disposed on a first side thereof that is configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure includes a plurality of indentations;   providing a cover disposed over the turning microstructure; and   physically coupling the cover to the light guide by an interlayer such that a plurality of open regions are between the interlayer and the plurality of indentations,   wherein the light guide has a first index of refraction and the interlayer has a second index of refraction and the second index of refraction is lower than the first index of refraction.   
     
     
         19 . A method of manufacturing a illumination device comprising:
 providing a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide, said light guide having turning microstructure disposed on a first side thereof that is configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure includes a plurality of indentations;   providing a cover disposed over the turning microstructure; and   physically coupling the cover to the light guide by an interlayer such that a plurality of regions between the interlayer and the plurality of indentations at least partially includes a material different from the interlayer.   
     
     
         20 . The method of  claim 19 , wherein said turning microstructure is formed by a method including:
 forming a dissolvable layer over the first side of the light guide;   forming the plurality of indentations through the dissolvable layer and the light guide;   depositing a material over the light guide so that the material at least partially fills the plurality of indentations; and   removing the dissolvable layer.   
     
     
         21 . The method of  claim 20 , wherein the dissolvable layer includes photoresist. 
     
     
         22 . The method of  claim 19 , wherein the light guide has a first index of refraction and the interlayer has a second index of refraction and the second index of refraction is lower than the first index of refraction. 
     
     
         23 . The method of  claim 19 , wherein the material includes a metallic material. 
     
     
         24 . The method of  claim 19 , further comprising filling the regions with a fluoroplastic material. 
     
     
         25 . The method of  claim 19 , further comprising filling the regions with an aerogel precursor material. 
     
     
         26 . The method of  claim 19 , further comprising filling the regions with a sol-gel material. 
     
     
         27 . A method of manufacturing a illumination device comprising:
 providing a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide, said light guide having turning microstructure disposed on a first side thereof that is configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure includes a plurality of indentations;   physically coupling a cover to the light guide, wherein the cover is disposed over the turning microstructure; and   wherein the light guide has a first index of refraction and the cover has a second index of refraction and the second index of refraction is lower than the first index of refraction.   
     
     
         28 . The method of  claim 27 , wherein the turning microstructure is formed on a light guide that includes a cross-linked polymer, the cover includes a polymeric material, and providing a cover physically coupled to the light guide includes diffusing portions of the cover to the light guide in areas between indentations. 
     
     
         29 . The method of  claim 27 , wherein physically coupling a cover to the light guide includes:
 coating a surface of the cover facing the light guide with a solvent, wherein the cover and the light guide are soluble in the solvent; and   placing the cover with the solvent over the light guide.   
     
     
         30 . The method of  claim 27 , further comprising applying pressure and heat to the cover to obtain inter-diffusion between the cover and the light guide in areas between the plurality of indentations. 
     
     
         31 . The method of  claim 27 , wherein providing a cover physically coupled to the light guide includes oxidizing a surface of the cover facing the light guide. 
     
     
         32 . A illumination device comprising:
 a light guide having a first end for receiving light and configured to support propagation of light along the length of the light guide;   a turning microstructure disposed on a first side of the light guide configured to turn light incident on the first side and to direct the light out a second opposite side of the light guide, wherein the turning microstructure includes a plurality of indentations;   a cover physically coupled to the light guide and disposed over the turning means;   a means for physically coupling between the cover and the light guide, wherein the coupling means physically couples the cover to the light guide; and   a plurality of regions between the coupling means and the plurality of indentations at least partially including a reflective means.   
     
     
         33 . The illumination device of  claim 32 , wherein the coupling means includes an interlayer. 
     
     
         34 . The illumination device of  claim 32 , wherein the reflective means includes a material different from the coupling means. 
     
     
         35 . The illumination device of  claim 34 , wherein the reflective means is a metal.