The Space Coronagraph Optical Bench (SCoOB): 5. End-to-end simulations of polarization aberrations

Polarization aberrations originating from the telescope and high-contrast imaging instrument optics introduce polarization-dependent speckles and associated errors in the image plane, affecting the measured exoplanet signal. Understanding this effect is critical for future space-based high-contrast imaging instruments that aim to image the Earth analogs with 10⁻¹⁰ raw contrast and characterize their atmospheres. We present end-to-end modeling of the polarization aberrations for a high-contrast imaging testbed, SCoOB. We use a vector vortex coronagraph (VVC) as the focal plane mask, incorporate polarization filtering, and estimate the peak contrast in the dark hole region 3-10 λ/D. The dominant polarization aberrations in the system are retardance defocus and tilt due to the OAPs and fold mirrors. Although the mean contrast in the dark hole region remains unaffected by the polarization aberrations, we see brighter speckles limiting the contrast to 1×10⁻⁹ at 1-2 λ/D. We extend the simulations using the measured retardance maps for the VVC and find that the mean contrast in SCoOB is more sensitive to retardance errors of the VVC and the QWP than the polarization aberrations.