Modeling the polarization aberrations of optical elements (Conference Presentation)

Abstract

Conventional ray tracing calculates the shape of wavefronts, but not their amplitudes or polarization states. Thin films, polarizers, diffraction gratings, crystals and even lenses, in addition to affecting the shape of wavefronts make contributions to the relative phase and amplitude of the light in an Optical System. These contributions will vary with polarization, field, and pupil position, adversely affecting the system performance. For sensitive optical systems, it is necessary to design around these effects with polarization ray tracing algorithms which are not only related to the optical path length, but include polarization dependent surface effects. This is done by supplementing the optical path length with calculations of the polarization ray tracing matrix (PRT). The adverse effects can then be described as the deviations from an identity Jones Pupil (polarization aberration), and Zernike polynomials can then be used to provide a simplified generalization of the polarization aberration that is still accurate. The Zernike terms will describe the amplitude transmission along the ray paths, the amplitude aberration, which is normally unavailable with a geometrical ray trace, and the Zernike terms will have the relative phase accumulations along ray paths, that describe phase variation with polarization state. Three different optical elements will be modeled: a wire grid polarizer, an anisotropic diffraction grating, and an injection molded lens with the polarization ray tracing software, Polaris-M. For each optical element, the polarization aberrations will be calculated and fit to Zernike polynomials. The effects of the aberrations on system performance will then be discussed and categorized.