Angular Selective Film

A method of fabricating an angular selective film, the method comprising:

• melting a first polymer material to form a melted first polymer material;
• melting a second polymer material to form a melted second polymer material;
• and
• coextruding at least the melted first polymer material and the melted second polymer material to form an angular selective film configured to have a higher transmittance for radiation having an incidence angle in a specified range as compared to radiation having an incidence angle outside of the specified range, the angular selective film comprising a plurality of multilayer modules stacked substantially along a normal direction of the angular selective film, in which each multilayer module comprises at least a first polymer layer comprising the first polymer material and a second polymer layer comprising the second polymer material,
• wherein the first and second polymer layers have at least one of the following properties:
• (i) the first polymer layer is isotropic, the second polymer layer is anisotropic, the refractive indices of the first and second polymer layers are substantially the same in a first direction, and the refractive indices of the first and second polymer layers are different in a second direction, or
• (ii) both the first and second polymer layers are anisotropic, the refractive indices of the first and second layers are substantially the same in a first direction, and the refractive indices of the first and second polymer layers are different in the second direction.