Patent ID: 7311952
Filing Date: 2007-12-25
Classification: C09K,G02B

Abstract:
1. A polymer film comprising a helical molecular structure which contains, in a direction transverse to the film, at least three sequences of helical molecular structure: a first sequence having a first helical pitch; a second sequence having a second helical pitch; and a third sequence having a third helical pitch, in the same order as listed, each of said first, second, and third sequences comprising at least three turns of helical molecular structure, the first helical pitch being shorter than the second helical pitch, and the third helical pitch being intermediate the first and second helical pitches, the change in helical pitch between the first helical pitch and the second helical pitch taking place in less then 10 turns of the helical structure, the helical pitches calculated based on reflection wavelength/average refractive index, the film comprising a single layer of a polymerized mixture of polymerizable liquid-crystalline material.