| abstract |
An optical film is produced by supplying a film, orienting the film substantially uniaxially, and heat setting the oriented film. A method of making an optical film includes providing a film, substantially uniaxially aligning the film, and heat setting the oriented film. The film 32 includes a polymer material that can develop birefringence. Alternatively, a heat setting step heats the film 32 to a temperature above the glass transition temperature of the at least one polymeric material and below the melting point of the polymeric material. [Selection] Figure 10 |