OPTICAL POLARIZING FILMS WITH DESIGNED COLOR SHIFTS DEPENDING ON THE ANGLE OF INCIDENCE, THE FILMS HAVING SUBSTANTIALLY NO REFLECTION BANDS IN THE VISIBLE SPECTRUM FOR NORMALLY INCIDENT LIGHT

摘要

Multilayer films are provided that exhibit a colored appearance when viewed at an oblique angle as a result of one or more reflection bands (32b, 32c) in the visible region of the spectrum. The films however provide no substantial reflection bands (32a) in either the visible or near infrared regions for light normally incident on the film. The films can be made to be clear at normal incidence to an arbitrary designed color at an oblique angle of incidence without necessarily becoming cyan. These properties can be achieved with a multilayer interference film construction with appropriate selection of layers thicknesses and refractive indices. The film comprises alternating layers of a first and a second light transmissible materials with at least one of the materials being birefringence, such that there is a substantial match of refractive indices of adjacent layers along the in- plane axis, and a substantial mismatch of refractive indices along the thickness axis.