[ { "id": "https://authors.library.caltech.edu/records/jv4vk-k1e23", "eprint_id": 87979, "eprint_status": "archive", "datestamp": "2023-08-22 18:49:06", "lastmod": "2023-10-18 21:34:49", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Polidan-R-S", "name": { "family": "Polidan", "given": "Ronald S." } }, { "id": "Breckinridge-J-B", "name": { "family": "Breckinridge", "given": "James B." }, "orcid": "0000-0002-9488-098X" }, { "id": "Lillie-C-F", "name": { "family": "Lillie", "given": "Charles F." } }, { "id": "MacEwen-H-A", "name": { "family": "MacEwen", "given": "Howard A." } }, { "id": "Flannery-M-R", "name": { "family": "Flannery", "given": "Martin R." } }, { "id": "Dailey-D-R", "name": { "family": "Dailey", "given": "Dean R." } } ] }, "title": "Innovative telescope architectures for future large space observatories", "ispublished": "pub", "full_text_status": "public", "keywords": "space telescopes; innovative architectures; segmented telescopes; in-space assembly and servicing", "note": "\u00a9 2016 Society of Photo-Optical Instrumentation Engineers (SPIE). \n\nPaper 16007SSP received Feb. 3, 2016; accepted for publication Jul. 22, 2016; published online Aug. 17, 2016. \n\nThe authors would like to acknowledge strong support and internal funding from Northrop Grumman Aerospace Systems and very helpful comments, suggestions, and criticisms from a variety of people, including Jonathan Arenberg, Suzanne Casement, Alberto Conti, Marc Postman, Ken Sembach, Wes Traub, and Harley Thronson.\n\n
Published - 041211_1.pdf
", "abstract": "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\u00d712-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.", "date": "2016-10", "date_type": "published", "publication": "Journal of Astronomical Telescopes, Instruments, and Systems", "volume": "2", "number": "4", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "pagerange": "Art. No. 041211", "id_number": "CaltechAUTHORS:20180718-155119352", "issn": "2329-4124", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180718-155119352", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Northrop Grumman Corporation" } ] }, "local_group": { "items": [ { "id": "GALCIT" } ] }, "doi": "10.1117/1.JATIS.2.4.041211", "primary_object": { "basename": "041211_1.pdf", "url": "https://authors.library.caltech.edu/records/jv4vk-k1e23/files/041211_1.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Polidan, Ronald S.; Breckinridge, James B.; et el." }, { "id": "https://authors.library.caltech.edu/records/vkyad-0em55", "eprint_id": 71198, "eprint_status": "archive", "datestamp": "2023-08-22 17:09:28", "lastmod": "2023-10-23 15:28:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Traub-W-A", "name": { "family": "Traub", "given": "Wesley A." } }, { "id": "Breckinridge-J-B", "name": { "family": "Breckinridge", "given": "James" }, "orcid": "0000-0002-9488-098X" }, { "id": "Greene-T-P", "name": { "family": "Greene", "given": "Thomas P." }, "orcid": "0000-0002-8963-8056" }, { "id": "Guyon-O", "name": { "family": "Guyon", "given": "Olivier" }, "orcid": "0000-0002-1097-9908" }, { "id": "Kasdin-N-J", "name": { "family": "Kasdin", "given": "N. Jeremy" } }, { "id": "Macintosh-B-A", "name": { "family": "Macintosh", "given": "Bruce" }, "orcid": "0000-0003-1212-7538" } ] }, "title": "Science yield estimate with the Wide-Field Infrared Survey Telescope coronagraph", "ispublished": "pub", "full_text_status": "public", "keywords": "coronagraphs; exoplanets; direct imaging; spectra; disks", "note": "\u00a9 2016 Society of Photo-Optical Instrumentation Engineers. Received June 15, 2015; Accepted February 22, 2016. Published online Mar. 18, 2016.\n\nWe thank the referee for valuable comments, which led to significant improvements in the text. This research has made use of the Exoplanet Orbit Database and the Exoplanet Data Explorer at exoplanets.org. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.\n\nPublished - JATIS_2_1_011020.pdf
", "abstract": "The coronagraph instrument (CGI) on the Wide-Field Infrared Survey Telescope will directly image and spectrally characterize planets and circumstellar disks around nearby stars. Here we estimate the expected science yield of the CGI for known radial-velocity (RV) planets and potential circumstellar disks. The science return is estimated for three types of coronagraphs: the hybrid Lyot and shaped pupil are the currently planned designs, and the phase-induced amplitude apodizing complex mask coronagraph is the backup design. We compare the potential performance of each type for imaging as well as spectroscopy. We find that the RV targets can be imaged in sufficient numbers to produce substantial advances in the science of nearby exoplanets. To illustrate the potential for circumstellar disk detections, we estimate the brightness of zodiacal-type disks, which could be detected simultaneously during RV planet observations.", "date": "2016-01", "date_type": "published", "publication": "Journal of Astronomical Telescopes, Instruments, and Systems", "volume": "2", "number": "1", "publisher": "Society of Photo-optical Instrumentation Engineers (SPIE)", "pagerange": "Art. No. 011020", "id_number": "CaltechAUTHORS:20161018-070312790", "issn": "2329-4124", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161018-070312790", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NASA/Caltech" }, { "agency": "NASA/JPL/Caltech" } ] }, "doi": "10.1117/1.JATIS.2.1.011020", "primary_object": { "basename": "JATIS_2_1_011020.pdf", "url": "https://authors.library.caltech.edu/records/vkyad-0em55/files/JATIS_2_1_011020.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Traub, Wesley A.; Breckinridge, James; et el." }, { "id": "https://authors.library.caltech.edu/records/4qnb9-nmh75", "eprint_id": 57944, "eprint_status": "archive", "datestamp": "2023-08-20 06:02:21", "lastmod": "2023-10-23 17:55:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Breckinridge-J-B", "name": { "family": "Breckinridge", "given": "James B." }, "orcid": "0000-0002-9488-098X" }, { "id": "Lam-Wai-Sze-T", "name": { "family": "Lam", "given": "Wai Sze T." } }, { "id": "Chipman-R-A", "name": { "family": "Chipman", "given": "Russell A." } } ] }, "title": "Polarization Aberrations in Astronomical Telescopes: The Point Spread Function", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Astronomical Society of the Pacific. Received 2014 October 20; accepted 2015 March 02; published 2015 March 31.\n\nPublished - 681280.pdf
", "abstract": "Detailed knowledge of the image of the point spread function (PSF) is necessary to optimize astronomical coronagraph masks and to understand potential sources of errors in astrometric measurements. The PSF for astronomical telescopes and instruments depends not only on geometric aberrations and scalar wave diffraction but also on those wavefront errors introduced by the physical optics and the polarization properties of reflecting and transmitting surfaces within the optical system. These vector wave aberrations, called polarization aberrations, result from two sources: (1) the mirror coatings necessary to make the highly reflecting mirror surfaces, and (2) the optical prescription with its inevitable non-normal incidence of rays on reflecting surfaces. The purpose of this article is to characterize the importance of polarization aberrations, to describe the analytical tools to calculate the PSF image, and to provide the background to understand how astronomical image data may be affected. To show the order of magnitude of the effects of polarization aberrations on astronomical images, a generic astronomical telescope configuration is analyzed here by modeling a fast Cassegrain telescope followed by a single 90\u00b0 deviation fold mirror. All mirrors in this example use bare aluminum reflective coatings and the illumination wavelength is 800 nm. Our findings for this example telescope are: (1) The image plane irradiance distribution is the linear superposition of four PSF images: one for each of the two orthogonal polarizations and one for each of two cross-coupled polarization terms. (2) The PSF image is brighter by 9% for one polarization component compared to its orthogonal state. (3) The PSF images for two orthogonal linearly polarization components are shifted with respect to each other, causing the PSF image for unpolarized point sources to become slightly elongated (elliptical) with a centroid separation of about 0.6 mas. This is important for both astrometry and coronagraph applications. (4) Part of the aberration is a polarization-dependent astigmatism, with a magnitude of 22 milliwaves, which enlarges the PSF image. (5) The orthogonally polarized components of unpolarized sources contain different wavefront aberrations, which differ by approximately 32 milliwaves. This implies that a wavefront correction system cannot optimally correct the aberrations for all polarizations simultaneously. (6) The polarization aberrations couple small parts of each polarization component of the light (\u223c10^(-4)) into the orthogonal polarization where these components cause highly distorted secondary, or \"ghost\" PSF images. (7) The radius of the spatial extent of the 90% encircled energy of these two ghost PSF image is twice as large as the radius of the Airy diffraction pattern. Coronagraphs for terrestrial exoplanet science are expected to image objects 10^(-10), or 6 orders of magnitude less than the intensity of the instrument-induced \"ghost\" PSF image, which will interfere with exoplanet measurements. A polarization aberration expansion which approximates the Jones pupil of the example telescope in six polarization terms is presented in the appendix. Individual terms can be associated with particular polarization defects. The dependence of these terms on angles of incidence, numerical aperture, and the Taylor series representation of the Fresnel equations lead to algebraic relations between these parameters and the scaling of the polarization aberrations. These \"design rules\" applicable to the example telescope are collected in \u00a7 5. Currently, exoplanet coronagraph masks are designed and optimized for scalar diffraction in optical systems. Radiation from the \"ghost\" PSF image leaks around currently designed image plane masks. Here, we show a vector-wave or polarization optimization is recommended. These effects follow from a natural description of the optical system in terms of the Jones matrices associated with each ray path of interest. The importance of these effects varies by orders of magnitude between different optical systems, depending on the optical design and coatings selected. Some of these effects can be calibrated while others are more problematic. Polarization aberration mitigation methods and technologies to minimize these effects are discussed. These effects have important implications for high-contrast imaging, coronagraphy, and astrometry with their stringent PSF image symmetry and scattered light requirements.", "date": "2015-05", "date_type": "published", "publication": "Publications of the Astronomical Society of the Pacific", "volume": "127", "number": "951", "publisher": "Astronomical Society of the Pacific", "pagerange": "445-468", "id_number": "CaltechAUTHORS:20150602-142109264", "issn": "0004-6280", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150602-142109264", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1086/681280", "primary_object": { "basename": "681280.pdf", "url": "https://authors.library.caltech.edu/records/4qnb9-nmh75/files/681280.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Breckinridge, James B.; Lam, Wai Sze T.; et el." } ]