Methods and apparatuses are provided for the manufacture of coextruded
polymeric multilayer optical films. The multilayer optical films have an
ordered arrangement of layers of two or more materials having particular
layer thicknesses and a prescribed layer thickness gradient throughout the
multilayer optical stack. The methods and apparatuses described allow
improved control over individual layer thicknesses, layer thickness
gradients, indices of refraction, interlayer adhesion, and surface
characteristics of the optical films. The methods and apparatuses
described are useful for making interference polarizers, mirrors, and
colored films that are optically effective over diverse portions of the
ultraviolet, visible, and infrared spectra.
