Polarization aberrations in an unobscured off-axis astronomical telescope and their effects on PSF ellipticity

Jing Luo; Xiaohui Zhang; Xu He

doi:10.1117/12.2579850

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5 November 2020 Polarization aberrations in an unobscured off-axis astronomical telescope and their effects on PSF ellipticity

Jing Luo, Xiaohui Zhang, Xu He

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Proceedings Volume 11570, AOPC 2020: Telescopes, Space Optics, and Instrumentation; 115700M (2020) https://doi.org/10.1117/12.2579850
Event: Applied Optics and Photonics China (AOPC 2020), 2020, Beijing, China

Abstract

Due to the continuously increasing detection ability in astronomy, polarization aberrations are playing more and more important roles in the performances of astronomical telescopes. In this paper, polarization aberrations of an unobscured off-axis astronomical telescope, which is designed to detect weak gravitational lensing signal, are analyzed via polarization ray trace. The diattenuation map and retardance map of each mirror of the telescope are obtained, and both its Jones pupil and amplitude response matrix are shown. Because of polarization aberrations, the imaging contrast of the telescope is limited to be at a level of 1e-5, and the PSF spatial distribution of the telescope varies, too. Optics ellipticity of the telescope is analyzed. The variations of optics ellipticity, which are dependent of field of view (FOV), are induced by polarization aberrations. The maximum and mean variations of the optics ellipticity in all FOVs are 7.5e-3 and 2.7e-3, respectively. At the FOV [-0.0487°, 0.155°], the maximum ellipticity interpolation error increases from 1.2e-4 to 1.1e-3. According to the analyses shown in this paper, we can see that polarization aberrations in the telescopes which aim to detect weak gravitational lensing signal and demand ultrahigh imaging performance are not negligible. Hence, polarization aberrations should be involved to optimize these telescopes.

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Jing Luo, Xiaohui Zhang, and Xu He "Polarization aberrations in an unobscured off-axis astronomical telescope and their effects on PSF ellipticity", Proc. SPIE 11570, AOPC 2020: Telescopes, Space Optics, and Instrumentation, 115700M (5 November 2020); https://doi.org/10.1117/12.2579850

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