Space Telescope Low-Scattered-Light Camera: A Model

Breckinridge, James B.; Kuper, Thomas G.; Shack, Roland V.

doi:10.1117/12.7973388

Cited by 14 publications

(8 citation statements)

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“…Therefore, the polarization content of the reflected beam is wavelength dependent. Breckinridge, Kuper, & Shack (1984) analyzed the properties of an all-reflecting coronagraph and discussed manufacturing tolerances required to control scattered light to the levels required for planet detection. Ward (1988) provides a summary of the optical methods for determining the optical constants of bulk materials and films and shows how these methods developed into the common practice of ellipsometry used by metallurgists.…”

Section: Prior Research On Astronomical Mirrormentioning

confidence: 99%

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

Breckinridge

Oppenheimer

2004

ApJ

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The properties of metal thin films have been largely overlooked in discussions of the technical limitations and problems that arise in the field of direct detection of exoplanets. Here, polarization properties and anisotropy properties of highly reflecting thin metal films are examined within the context of the requirements for the ultralow-scattered-light system performance of coronagraphs applied to space and ground-based high-contrast, whitelight astronomy. Wavelength-dependent optical constants for highly reflecting thin metal films, taken from the literature, are used to calculate the polarization-dependent transmissivity of a typical coronagraph. The effects of degraded performance on the astronomical science are examined. Suggestions are made for future work.

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Section: Prior Research On Astronomical Mirrormentioning

confidence: 99%

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

Breckinridge

Oppenheimer

2004

ApJ

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“…Discontinuous telescope pupils, that is telescope apertures that have some portion of the aperture blocked are responsible for diffraction "noise" at the image plane. Breckinridge, Kuper and Shack (1982) 5 were the first to discuss the role of secondary support diffraction spikes in finding exoplanets. Figure 2 below shows the diffraction pattern from the HST caused by the secondary support structure.…”

Section: Ground and Space Telescopesmentioning

confidence: 99%

Exoplanet telescope diffracted light minimized: the pinwheel-pupil solution

Breckinridge

Harvey²,

Crabtree

et al. 2018

Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave

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Terrestrial exoplanets shine in light reflected from a parent star. Optical spectra are required to provide evidence of a life-supporting environment. Exoplanets are very faint and their optical spectra are contaminated by the spectrum of the parent star. High angular resolution provided by large apertures is needed to distinguish between the spectrum of the exoplanet and its star. Today, large aperture telescopes use segmented primary mirrors that employ close-packed hexagonal segments. The telescope primary mirror is periodically discontinuous with straight lines. These discontinuities scatter unwanted radiation from the much brighter parent star across the field of view to obscure the light from the very faint terrestrial exoplanet. These discontinuities, which mimic a diffraction grating, result in a non-uniform distribution of background light across the image plane. This non-uniformity masks or hides exoplanets from view, to reduce the number of exoplanets that can be observed with a large aperture telescope or to reduce the quality of spectra and thus lead to misinterpretation of data. Here we introduce the concept of the pinwheel pupil whose unique diffraction pattern significantly reduces the non-uniform distribution of background radiation. Diffraction patterns from pinwheel pupils are compared to the monolithic filled aperture, the classical Cassegrain, the 60-degree symmetry of the hexagonal segments (JWST, E-ELT, etc.). Diffraction "spikes" are reduced by at least 10 5. We discuss the "pinwheel pupil" advantages to spectroscopy, image processing, and observatory operations. We show that, segment fabrication of curved-sided mirrors is not more difficult than fabrication of hexagonal mirror segments.. This is the report of quantitative study of Fraunhofer (far field) diffraction patterns produced by three different topologies or architectures of mirror segmentation, when illuminated by a plane wave of monochromatic white-light. A plot, in angular units of the intensity as a function of azimuth, Phi f , within annular rings at different FOVs, centered on the system axis of the diffraction pattern will be presented. The advantages of the segmented pinwheel pupil is discussed.

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“…For over 30 years, scalar approximations to the vector EM field have been used to model exoplanet coronagraphs. 23 Today, coronagraphs are still optimized using the intensity PSF that is given by the scalar relationship where PSF k<¼k is the end-to-end optical system point spread function one obtains from parallel-polarized light in and analyzing the parallel-polarized light out. PSF ⊥<¼⊥ is the end-to-end optical system point spread function one obtains from perpendicular-polarized light in and analyzing the perpendicular-polarized light out.…”

Section: Exoplanet Applicationsmentioning

confidence: 99%

Innovative telescope architectures for future large space observatories

Polidan

Breckinridge²,

Lillie³

et al. 2016

J. Astron. Telesc. Instrum. Syst

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Over the past few years, we have developed a concept for an evolvable space telescope (EST) that is assembled on orbit in three stages, growing from a 4 × 12-m telescope in Stage 1, to a 12-m filled aperture in Stage 2, and then to a 20-m filled aperture in Stage 3. Stage 1 is launched as a fully functional telescope and begins gathering science data immediately after checkout on orbit. This observatory is then periodically augmented in space with additional mirror segments, structures, and newer instruments to evolve the telescope over the years to a 20-m space telescope. We discuss the EST architecture, the motivation for this approach, and the benefits it provides over current approaches to building and maintaining large space observatories.

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Space Telescope Low-Scattered-Light Camera: A Model

Cited by 14 publications

References 0 publications

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

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

Exoplanet telescope diffracted light minimized: the pinwheel-pupil solution

Innovative telescope architectures for future large space observatories

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