Abstract: A method includes attaching a clip array to opposing edges of a polymer thin film, the clip array having a plurality of first clips slidably disposed on a first track located proximate to a first edge of the polymer thin film and a plurality of second clips slidably disposed on a second track located proximate to a second edge of the polymer thin film, applying a positive in-plane strain to the polymer thin film along a transverse direction by increasing a distance between the first and second clips, and decreasing an inter-clip spacing amongst the first clips and amongst the second clips along a machine direction while applying the in-plane strain to form an optically anisotropic polymer thin film. During stretching, a strain rate of the thin film may be decreased and/or a temperature of the thin film may be increased.