Method of making light directing structures

Abstract

A method of making light directing structures using a prismatic optical film and a low-refractive index resin. The prismatic optical film has a plurality of linear refractive prisms formed in its surface. The prisms extend parallel to one another and define a series of refractive walls. The resin is applied to the prism-carrying surface of the film so as to form a generally uniform optical layer. The resin may be further cured to a solid form to form a monolithic layered light bending structure incorporating an embedded corrugated optical interface with a stepped change in a refractive index and having generally smooth outer surfaces.

What is claimed is: 
     
         1 . A method of making light directing structures, comprising:
 providing a first optical film formed from a first optically transmissive material and having a generally smooth first surface and an opposing corrugated second surface, the corrugated second surface comprising a plurality of linear refractive prisms extending parallel to one another and each defining a first wall forming a first dihedral angle with respect to a plane of the first optical film and a second wall forming a second dihedral angle with respect to the plane of the first optical film;   providing an optically transmissive resin made from a second optically transmissive material having a lower refractive index and a lower softening point than the first optically transmissive material; and   coating the corrugated second surface with the optically transmissive resin so as to form a generally uniform optical layer with a generally smooth outer surface and a light permeable corrugated optical interface between the first and second optically transmissive materials,   wherein the light permeable corrugated optical interface is characterized by a stepped change in a refractive index.   
     
     
         2 . A method of making light directing structures as recited in  claim 1 , comprising curing the optically transmissive resin to a solid form. 
     
     
         3 . A method of making light directing structures as recited in  claim 1 , further comprising providing a mirrored surface and positioning the mirrored surface in an energy receiving relationship with respect to a layered optical film structure formed by the first optical film and the generally uniform optical layer. 
     
     
         4 . A method of making light directing structures as recited in  claim 1 , further comprising providing a second optical film formed from a third optically transmissive material and positioning the second optical film in contact with the generally uniform optical layer. 
     
     
         5 . A method of making light directing structures as recited in  claim 4 , wherein the third optically transmissive material has a different refractive index than the first and second optically transmissive materials. 
     
     
         6 . A method of making light directing structures as recited in  claim 5 , further comprising providing a third optical film formed from a fourth optically transmissive material which has a different refractive index than the first and second optically transmissive materials. 
     
     
         7 . A method of making light directing structures as recited in  claim 1 , further comprising providing a second optical film formed from a third optically transmissive material and bonding the second optical film to the generally smooth outer surface. 
     
     
         8 . A method of making light directing structures as recited in  claim 7 , wherein the third optically transmissive material has a different refractive index than the first and second optically transmissive materials. 
     
     
         9 . A method of making light directing structures as recited in  claim 1 , further comprising providing an optical waveguide and disposing a layered optical film structure formed by the first optical film and the generally uniform optical layer in an optical communication relationship with respect to the optical waveguide. 
     
     
         10 . A method of making light directing structures as recited in  claim 1 , comprising heating the optically transmissive resin to a temperature above a softening point of the second optically transmissive material but below a softening point of the first optically transmissive material. 
     
     
         11 . A method of making light directing structures as recited in  claim 1 , wherein at least some of the plurality of linear refractive prisms extend along a circular or arcuate path. 
     
     
         12 . A method of making light directing structures as recited in  claim 1 , wherein at least some of the plurality of linear refractive prisms extend along a curved path. 
     
     
         13 . A method of making light directing structures as recited in  claim 1 , wherein each of the plurality of linear refractive prisms extends along a curvilinear reference line. 
     
     
         14 . A method of making light directing structures as recited in  claim 1 , wherein at least some of the plurality of linear refractive prisms extend between two edges of the first optical film along a path forming a non-zero angle with respect to at least one of the two edges. 
     
     
         15 . A method of making light directing structures as recited in  claim 1 , wherein the first dihedral angle is approximately the same as the second dihedral angle. 
     
     
         16 . A method of making light directing structures as recited in  claim 1 , wherein the first dihedral angle is different from the second dihedral angle. 
     
     
         17 . A method of making light directing structures as recited in  claim 1 , wherein the first dihedral angle is different from the second dihedral angle, and wherein both the first and second dihedral angles are greater than 0° and less than 90°. 
     
     
         18 . A method of making light directing structures as recited in  claim 1 , wherein at least one of the first and second walls is configured to redirect light propagating transversely through the first optical film using total internal reflection. 
     
     
         19 . A method of making light directing structures as recited in  claim 1 , wherein the light permeable corrugated optical interface comprises a first plurality of facets alternating with a second plurality of facets, wherein the first plurality of facets forms first dihedral angles with respect to the generally smooth first surface, wherein the second plurality of facets forms second dihedral angles with respect to the generally smooth first surface, wherein the first dihedral angles are different from the second dihedral angles and progressively increase with a distance from a predetermined location of a layered optical film structure formed by the first optical film and the generally uniform optical layer. 
     
     
         20 . A method of making light directing structures as recited in  claim 1 , comprising flexing a layered optical film structure formed by the first optical film and the generally uniform optical layer to a curved shape.