TY - JOUR
T1 - Polarization aberrations in next-generation giant segmented mirror telescopes (GSMTs)
T2 - I. Effect on the coronagraphic performance
AU - Anche, Ramya M.
AU - Ashcraft, Jaren N.
AU - Haffert, Sebastiaan Y.
AU - Millar-Blanchaer, Maxwell A.
AU - Douglas, Ewan S.
AU - Snik, Frans
AU - Williams, Grant
AU - Van Holstein, Rob G.
AU - Doelman, David
AU - Van Gorkom, Kyle
AU - Skidmore, Warren
N1 - Publisher Copyright:
© The Authors 2023.
PY - 2023/4/1
Y1 - 2023/4/1
N2 - Context. Next-generation large segmented mirror telescopes are expected to perform direct imaging and characterization of Earth-like rocky planets, which requires contrast limits of 10-7 to 10-8 at wavelengths from I to J band. One critical aspect affecting the raw on-sky contrast are polarization aberrations (i.e., polarization-dependent phase and amplitude patterns in the pupil) arising from the reflection from the telescope-s mirror surfaces and instrument optics. These polarization aberrations induce false signals for polarimetry that can be calibrated to a certain degree, but they can also fundamentally limit the achievable contrast of coronagraphic systems. Aims. We simulate the polarization aberrations and estimate their effect on the achievable contrast for three next-generation ground-based large segmented mirror telescopes. Methods. We performed ray-tracing in Zemax® and computed the polarization aberrations and Jones pupil maps using the polarization ray-tracing algorithm. The impact of these aberrations on the contrast is estimated by propagating the Jones pupil maps through a set of idealized coronagraphs using hcipy, a physical optics-based simulation framework. Results. The optical modeling of the giant segmented mirror telescopes (GSMTs) shows that polarization aberrations create significant leakage through a coronagraphic system. The dominant aberration is retardance defocus, which originates from the steep angles on the primary and secondary mirrors. The retardance defocus limits the contrast to 10-5 to 10-4 at 1 λ/D at visible wavelengths, and 10-5 to 10-6 at infrared wavelengths. The simulations also show that the coating plays a major role in determining the strength of the aberrations. Conclusions. Polarization aberrations will need to be considered during the design of high-contrast imaging instruments for the next generation of extremely large telescopes. This can be achieved either through compensation optics, robust coronagraphs, specialized coatings, calibration, and data analysis approaches, or by incorporating polarimetry with high-contrast imaging to measure these effects.
AB - Context. Next-generation large segmented mirror telescopes are expected to perform direct imaging and characterization of Earth-like rocky planets, which requires contrast limits of 10-7 to 10-8 at wavelengths from I to J band. One critical aspect affecting the raw on-sky contrast are polarization aberrations (i.e., polarization-dependent phase and amplitude patterns in the pupil) arising from the reflection from the telescope-s mirror surfaces and instrument optics. These polarization aberrations induce false signals for polarimetry that can be calibrated to a certain degree, but they can also fundamentally limit the achievable contrast of coronagraphic systems. Aims. We simulate the polarization aberrations and estimate their effect on the achievable contrast for three next-generation ground-based large segmented mirror telescopes. Methods. We performed ray-tracing in Zemax® and computed the polarization aberrations and Jones pupil maps using the polarization ray-tracing algorithm. The impact of these aberrations on the contrast is estimated by propagating the Jones pupil maps through a set of idealized coronagraphs using hcipy, a physical optics-based simulation framework. Results. The optical modeling of the giant segmented mirror telescopes (GSMTs) shows that polarization aberrations create significant leakage through a coronagraphic system. The dominant aberration is retardance defocus, which originates from the steep angles on the primary and secondary mirrors. The retardance defocus limits the contrast to 10-5 to 10-4 at 1 λ/D at visible wavelengths, and 10-5 to 10-6 at infrared wavelengths. The simulations also show that the coating plays a major role in determining the strength of the aberrations. Conclusions. Polarization aberrations will need to be considered during the design of high-contrast imaging instruments for the next generation of extremely large telescopes. This can be achieved either through compensation optics, robust coronagraphs, specialized coatings, calibration, and data analysis approaches, or by incorporating polarimetry with high-contrast imaging to measure these effects.
KW - Instrumentation: adaptive optics
KW - Instrumentation: polarimeters
KW - Methods: numerical
KW - Planets and satellites: terrestrial planets
KW - Polarization
KW - Telescopes
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U2 - 10.1051/0004-6361/202245651
DO - 10.1051/0004-6361/202245651
M3 - Article
AN - SCOPUS:85153395037
SN - 0004-6361
VL - 672
JO - Astronomy and astrophysics
JF - Astronomy and astrophysics
M1 - A121
ER -