This work presents a wide angle phase retarder by using a single anisotropic Ta2O5 columnar thin film. The single anisotropic Ta2O5 columnar thin film can provide phase retardation between two tangential eigenvectors to modulate the polarization state of light reflected from the prism-coupling system (BK7 prism/anisotropic thin film/air). In experiment, glancing angle deposition technique is used to prepare single layer film of Ta2O5 tilted nanorod array with thickness 270nm. In this analysis, we use wave tracing based on the Berreman calculus to calculate the variations of phases of eigen-waves in the anisotropic thin film as the electromagnetic wave is incident to the prism-coupling system. The uniform phase retardation can be observed in a wide angle range. A linearly polarized incident ray can be reflected as a specific elliptical polarized ray uniformly over the range. Similarly, the wide angle and broadband polarization conversion reflectance with high efficiency also exists in the single anisotropic Ta2O5 columnar thin film. The single anisotropic Ta2O5 columnar thin film can be useful for the further application in optical components design.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.