Results of the summarizing process for the arXiv paper: 2304.02079v1

Next-generation large segmented mirror telescopes are being developed to directly image and characterize Earth-like rocky planets, which requires high contrast limits of $10^{-7}$ to $10^{-8}$ at wavelengths ranging from I to J band. However, one critical aspect that affects the raw on-sky contrast is polarization aberrations arising from the reflection of light from the telescope's mirror surfaces and instrument optics. In a recent study, researchers simulated these aberrations and estimated their effect on achievable contrast for three next-generation ground-based large segmented mirror telescopes. The study involved performing ray-tracing in Zemax and computing the polarization aberrations and Jones pupil maps using a polarization ray-tracing algorithm. The impact of these aberrations on contrast was then estimated by propagating the Jones pupil maps through a set of idealized coronagraphs using hcipy, a physical optics-based simulation framework. The optical modeling of giant segmented mirror telescopes (GSMTs) showed that polarization aberrations create significant leakage through a coronagraphic system. The study found that retardance defocus is the dominant aberration originating from steep angles on primary and secondary mirrors, limiting contrast to $10^{-5}$ to $10^{-4}$ at 1 $\lambda/D$ at visible wavelengths and $10^{-5}$ to $10^{-6}$ at infrared wavelengths. The simulations also revealed that coatings play an important role in determining the strength of these aberrations. Therefore, it is essential to consider polarization aberrations during high-contrast imaging instrument design for next generation extremely large telescopes. The paper provides a detailed description of each telescope's optical layout and proposed coronagraphic instruments in Section 2; for instance, it describes ELT with a 39m diameter segmented primary mirror currently under construction on Cerro Armazones in northern Chile expected to have its first light in 2027. It has five mirrors with an intermediate focus, as shown in Figure 1. The Multi AO Imaging Camera for Deep Observations (MICADO) is one of the proposed coronagraphic instruments. Section 3 provides a summary of the polarization ray tracing algorithm and estimation of polarization aberrations while Section 4 presents Jones pupil maps evaluated at the exit pupil of each telescope. Section 5 shows diattenuation and retardance variation on all mirror surfaces for coatings used in these telescopes. The description of coronagraphs and simulations to estimate achievable contrast is given in Section 6; moreover, this section discusses mitigation strategies such as polarimetry with high contrast imaging or incorporating compensation optics, robust coronagraphs, specialized coatings, calibration techniques, and data analysis approaches that can be used to reduce or eliminate these effects. Finally, Section 8 provides a summary emphasizing that considering polarization aberrations during high contrast imaging instrument design is crucial for next generation extremely large telescopes.

• Next-generation large segmented mirror telescopes are being developed to directly image and characterize Earth-like rocky planets
• High contrast limits of $10^{-7}$ to $10^{-8}$ are required at wavelengths ranging from I to J band
• Polarization aberrations arising from the reflection of light from the telescope's mirror surfaces and instrument optics affect the raw on-sky contrast
• Researchers simulated these aberrations and estimated their effect on achievable contrast for three next-generation ground-based large segmented mirror telescopes using ray-tracing in Zemax and a polarization ray-tracing algorithm
• The impact of these aberrations on contrast was estimated by propagating Jones pupil maps through idealized coronagraphs using hcipy, a physical optics-based simulation framework
• Polarization aberrations create significant leakage through a coronagraphic system, with retardance defocus being the dominant aberration originating from steep angles on primary and secondary mirrors, limiting contrast to $10^{-5}$ to $10^{-4}$ at 1 $\lambda/D$ at visible wavelengths and $10^{-5}$ to $10^{-6}$ at infrared wavelengths.
• Coatings play an important role in determining the strength of these aberrations.
• It is essential to consider polarization aberrations during high-contrast imaging instrument design for next generation extremely large telescopes.
• The paper provides a detailed description of each telescope's optical layout and proposed coronagraphic instruments in Section 2.
• Mitigation strategies such as polarimetry with high contrast imaging or incorporating compensation optics, robust coronagraphs, specialized coatings, calibration techniques, and data analysis approaches can be used to reduce or eliminate these effects.
• Section 8 emphasizes that considering polarization aberrations during high contrast imaging instrument design is crucial for next generation extremely large telescopes.

Polarization Aberrations and Their Impact on Achievable Contrast for Next-Generation Large Segmented Mirror Telescopes

Direct imaging of Earth-like rocky planets requires high contrast limits of $10^{-7}$ to $10^{-8}$ at wavelengths ranging from I to J band. However, one critical aspect that affects the raw on-sky contrast is polarization aberrations arising from the reflection of light from the telescope's mirror surfaces and instrument optics. In a recent study, researchers simulated these aberrations and estimated their effect on achievable contrast for three next-generation ground-based large segmented mirror telescopes.

Optical Modeling of Giant Segmented Mirror Telescopes

The study involved performing ray tracing in Zemax and computing the polarization aberrations and Jones pupil maps using a polarization ray tracing algorithm. The impact of these aberrations on contrast was then estimated by propagating the Jones pupil maps through a set of idealized coronagraphs using hcipy, a physical optics based simulation framework. The optical modeling showed that polarization aberrations create significant leakage through a coronagraphic system, limiting contrast to $10^{-5}$ to $10^{-4}$ at 1 $\lambda/D$ at visible wavelengths and $10^{-5}$ to $10^{-6}$ at infrared wavelengths. The simulations also revealed that coatings play an important role in determining the strength of these aberrations.

Telescope Description

The paper provides a detailed description of each telescope's optical layout and proposed coronagraphic instruments in Section 2; for instance, it describes ELT with a 39m diameter segmented primary mirror currently under construction on Cerro Armazones in northern Chile expected to have its first light in 2027. It has five mirrors with an intermediate focus, as shown in Figure 1. The Multi AO Imaging Camera for Deep Observations (MICADO) is one of the proposed coronagraphic instruments.

Polarization Ray Tracing Algorithm

Section 3 provides a summary of the polarization ray tracing algorithm used to compute polarization aberrations and Jones pupil maps evaluated at exit pupils for each telescope while Section 4 presents results obtained from this algorithm showing diattenuation and retardance variation on all mirror surfaces for coatings used in these telescopes.

Coronagraphs & Simulations

Section 5 shows simulations performed by propagating Jones pupil maps through idealized coronagraphs using hcipy which estimate achievable contrasts due to presence or absence of polarizing elements such as retarders or waveplates between mirrors or within instrument optics respectively along with other mitigation strategies such as polarimetry with high contrast imaging or incorporating compensation optics, robust coronagraphs, specialized coatings etc., calibration techniques & data analysis approaches that can be used to reduce or eliminate these effects are discussed here too .

Conclusion

Finally , section 8 provides conclusion emphasizing that considering polarization aberration during high contrast imaging instrument design is crucial for next generation extremely large telescopes .