Polarization Effects in Reflecting Coronagraphs for White‐Light Applications in Astronomy

Breckinridge, James B.; Oppenheimer, Ben R.

doi:10.1086/379872

Cited by 68 publications

(49 citation statements)

References 21 publications

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“…Sources of polarization-induced anisoplanatism are identified, examples derived and the role of the complex (real and imaginary) vector waves is presented. This paper is a continuation of our previous work 1,2,3,4,5,6 on the subject of physical optics vector wave propagation through a typical astronomical telescope optical system and the affects of this propagation on scientific astronomical data quality. In 2004, Breckinridge and Oppenheimer 3 showed that polarization introduced by image forming optics internal to a telescope & coronagraph optical system adds noise to the system and masks signatures important for the characterization of exoplanets.…”

Section: Introductionmentioning

confidence: 76%

“…However, any surface in the entire optical path that introduces partial polarization, either circular or linear will distort the PSF and will increase scattered light. Optical filters, diffraction gratings 18 , fold mirrors 19,20 needed for packaging, and the necessary powered optical elements 21 to control geometric aberrations introduce internal polarization to modify the PSF. Such polarization induced aberration needs to be understood in detail to optimize the detection and characterization of exoplanets using coronagraphy and astrometry.…”

Section: Image Formation Is An Interference Phenomenonmentioning

confidence: 99%

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Self-induced polarization anisoplanatism

Breckinridge

2013

SPIE Proceedings

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This paper suggests that the astronomical science data recorded with low F# telescopes for applications requiring a known point spread function shape and those applications requiring instrument polarization calibration may be compromised unless the effects of vector wave propagation are properly modeled and compensated. Exoplanet coronagraphy requires "matched filter" masks and explicit designs for the real and imaginary parts for the mask transmittance. Three aberration sources dominate image quality in astronomical optical systems: amplitude, phase and polarization. Classical ray-trace aberration analysis used today by optical engineers is inadequate to model image formation in modern low F# highperformance astronomical telescopes. We show here that a complex (real and imaginary) vector wave model is required for high performance, large aperture, very wide-field, low F# systems.Self-induced polarization anisoplanatism (SIPA) reduces system image quality, decreases contrast and limits the ability of image processing techniques to restore images. This paper provides a unique analysis of the image formation process to identify measurements sensitive to SIPA. Both the real part and the imaginary part of the vector complex wave needs to be traced through the entire optical system, including each mirror surface, optical filter, and all masks. Only at the focal plane is the modulus squared taken to obtain an estimate of the measured intensity.This paper also discusses the concept of the polarization conjugate filter, suggested by the author to correct telescope/instrument corrupted phase and amplitude and thus mitigate 6 , in part the effects of phase and amplitude errors introduced by reflections of incoherent white-light from metal coatings.

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Section: Introductionmentioning

confidence: 76%

Section: Image Formation Is An Interference Phenomenonmentioning

confidence: 99%

Self-induced polarization anisoplanatism

Breckinridge

2013

SPIE Proceedings

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“…Several coronagraph architectures have been proposed [7][8][9][10][11][12][13] . Each one of these will have degraded performance because of Fresnel polarization apodization.…”

Section: Polarization Compensationmentioning

confidence: 99%

“…The ring mask, shown at plane 4 is not a powered element. Although the telescope primary may be quite large, 8 meters as planned in NASA exoplanet missions [7][8][9][10][11][12] , the mitigation of Fresnel Polarization can be done at a much smaller and convenient pupil plane such as at plane 4 where the ring mask is located. The functions of the polarization compensator and ring mask can be combined, as we are describing under this effort.…”

Section: Polarization Compensation In Coronagraph System Design Consimentioning

confidence: 99%

Intelligent Optical Systems Using Adaptive Optics

Clark

2012

Advances in Science and Technology

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Until recently, the phrase adaptive optics generally conjured images of large deformable mirrors being integrated into telescopes to compensate for atmospheric turbulence. However, the development of smaller, cheaper devices has sparked interest for other aerospace and commercial applications. Variable focal length lenses, liquid crystal spatial light modulators, tunable filters, phase compensators, polarization compensation, and deformable mirrors are becoming increasingly useful for other imaging applications including guidance navigation and control (GNC), coronagraphs, foveated imaging, situational awareness, autonomous rendezvous and docking, non-mechanical zoom, phase diversity, and enhanced multi-spectral imaging. The active components presented here allow flexibility in the optical design, increasing performance. In addition, the intelligent optical systems presented offer advantages in size and weight and radiation tolerance.

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“…13 The dependence of IP on the incident angles of the mirror has already been estimated and presented for silver, gold, and aluminum coating. 14 A model has been developed to estimate the IP at the focus of a very large telescope (VLT). 15 They use Stokes/Mueller formalism to estimate the IP for the telescope and the Nasmyth adaptive optics system (NACO) for the K s band.…”

Section: Introductionmentioning

confidence: 99%

Analysis of polarization introduced due to the telescope optics of the Thirty Meter Telescope

Anche

Sen

Anupama

et al. 2018

J. Astron. Telesc. Instrum. Syst.

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Abstract. An analytical model has been developed to estimate the polarization effects, such as instrumental polarization (IP), crosstalk (CT), and depolarization, due to the optics of the Thirty Meter Telescope. These are estimated for the unvignetted field-of-view and the wavelengths of interest. The model estimates an IP of 1.26% and a CT of 44% at the Nasmyth focus of the telescope at the wavelength of 0.6 μm at field angle zero with the telescope pointing to zenith. Mueller matrices have been estimated for the primary, secondary, and Nasmyth mirrors. It is found that some of the Mueller matrix elements of the primary and secondary mirrors show a fourfold azimuthal antisymmetry, which indicates that the polarization at the Cassegrain focus is negligible. At the inclined Nasmyth mirror, there is no azimuthal antisymmetry in the matrix elements, and this results in nonzero values for IP and CT, which would negatively impact the polarization measurements at the telescope focus. The averaged Mueller matrix is estimated at the Nasmyth focus at different instrument ports and various zenith angles of the telescope. The variation in the Mueller matrix elements for different coatings is also estimated. The impact of this polarization effect on the science case requirements has been discussed. This analysis will help in achieving precise requirements for future instruments with polarimetric capability.

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Polarization Effects in Reflecting Coronagraphs for White‐Light Applications in Astronomy

Cited by 68 publications

References 21 publications

Self-induced polarization anisoplanatism

Self-induced polarization anisoplanatism

Intelligent Optical Systems Using Adaptive Optics

Analysis of polarization introduced due to the telescope optics of the Thirty Meter Telescope

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