Optical film having a surface with rounded structures

Abstract

The present disclosure is directed to optical devices including a light source and an optical film having a first surface disposed to receive light from the light source and a second surface facing away from the light source. The second surface includes a two-dimensional array of closely packed substantially hemispherically-shaped structures. In some implementations of the present disclosure, the optical film further includes a substrate portion having an optical characteristic different from optical characteristics of the second surface comprising the two dimensional array.

1  An optical device, comprising:
 a light source;   a light gating device; and   a gain diffuser exhibiting an optical gain of at least about 1.2 and comprising a first surface receiving light from the light source and a second surface facing the light gating device and comprising a two-dimensional array of closely packed substantially hemispherically-shaped structures.   
   
   
       2 . The optical device of  claim 1 , wherein the gain diffuser exhibits an optical gain of at least about 1.4. 
   
   
       3 . The optical device of  claim 1  further comprising at least one of a polarizer film, a diffuser film, a brightness enhancing film and a turning film. 
   
   
       4 . The optical device of  claim 3 , wherein the polarizer film comprises a diffuse reflective polarizer film. 
   
   
       5 . The optical device of  claim 1 , wherein a refractive index of the substantially hemispherically-shaped structures is lower than a refractive index of a layer in the gain diffuser. 
   
   
       6 . A direct-lit backlight, comprising:
 a light source;   a light gating device; and   a gain diffuser exhibiting an optical gain of at least about 1.2 and comprising a first surface facing the light source and a second surface facing the light gating device and comprising an array of structures, wherein an output light intensity distribution of the backlight has a primary, but not a secondary, peak.   
   
   
       7 . The optical device of  claim 6 , wherein the gain diffuser exhibits an optical gain of at least about 1.4. 
   
   
       8 . The direct-lit backlight of  claim 6 , wherein the output light intensity distribution has cylindrical symmetry. 
   
   
       9 . The direct-lit backlight of  claim 6 , wherein the output light intensity distribution decreases monotonically from the primary peak. 
   
   
       10 . The direct-lit backlight of  claim 6 , wherein the output light intensity distribution has a wider viewing angle relative to a viewing angle of the backlight absent the gain diffuser. 
   
   
       11 . The direct-lit backlight of  claim 6 , wherein the array of structures comprises an array of substantially hemispherically-shaped structures.