&lt;title&gt;Stray light analysis of a reflecting UV Coronagraph/Polarimeter with multilayer optics&lt;/title&gt;

Fineschi, Silvano; Romoli, M.; Hoover, Richard B.; Baker, Phillip C.; Zukic, Muamer; Kim, Jongmin; Walker, Arthur B. C.

doi:10.1117/12.168591

Cited by 9 publications

(10 citation statements)

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“…24 for the FoV of 2.2 deg are summarized in Table 7 at BOL and in Table 8 at EOL. The results of Tables 7 and 8 obtained with Zemax OpticStudio are consistent with those obtained with two different approaches: the Monte Carlo ray trace with ASAP 12 and a semianalytical model 6 as summarized in Table 9. Taking into account that the three approaches were developed independently, the results are in considerable agreement and show compliance with the requirement of stray-light level for both the UV and VL channels.…”

Section: Results For the Stray Lightsupporting

confidence: 81%

“…Section 5 compares the results obtained with two different approaches: a Monte Carlo ray trace with ASAP 5 and a semianalytical method. 6 2 Optomechanical Model of the METIS Telescope The results of the stray-light simulations and the compliance to the functional requirements mainly depend on how the physical properties of the objects hit by the optical rays are reproduced. Then, the maximum effort has been used in modeling all of the surfaces of the telescope to reproduce their reflecting, transmitting, absorbing, and diffusing properties.…”

Section: Stray-light Analyses Of the Multielement Telescope For Imaging And Spectroscopy Coronagraph On Solar Orbiter 1 Introductionmentioning

confidence: 99%

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Stray-light analyses of the multielement telescope for imaging and spectroscopy coronagraph on Solar Orbiter

2018

Opt. Eng.

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The modeling of the scattering phenomena for the multielement telescope for imaging and spectroscopy (METIS) coronagraph on board the European Space Agency Solar Orbiter is reported. METIS is an inverted occultation coronagraph including two optical paths: the broadband imaging of the full corona in linearly polarized visible-light (580 to 640 nm) and the narrow-band imaging of the full corona in the ultraviolet Lyman-α (121.6 nm). METIS will have the unique opportunity of observing the solar outer atmosphere as close to the Sun as 0.28 AU and from up to 35 deg out-of-ecliptic. The stray-light simulations performed on the UV and VL channels of the METIS analyzing the contributors of surface microroughness, particulate contamination, cosmetic defects, and diffraction are reported. The results obtained with the nonsequential modality of Zemax OpticStudio are compared with two different approaches: the Monte Carlo ray trace with Advanced Systems Analysis Program (ASAP ® ) and a semianalytical model. The results obtained with the three independently developed approaches are in considerable agreement and show compliance to the requirement of stray-light level for both the UV and VL channels.

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Section: Results For the Stray Lightsupporting

confidence: 81%

Section: Stray-light Analyses Of the Multielement Telescope For Imaging And Spectroscopy Coronagraph On Solar Orbiter 1 Introductionmentioning

confidence: 99%

Stray-light analyses of the multielement telescope for imaging and spectroscopy coronagraph on Solar Orbiter

2018

Opt. Eng.

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“…The part specularly reflected by the mirror is blocked by the internal occulter, but the part that is scattered by the surface can reach the focal plane [8]. The surface scattering properties are characterized by the bi-directional scattering distribution function (BSDF) and the total integrated scatter (TIS).…”

Section: Icso 2012mentioning

confidence: 99%

Evaluation of the stray light from the diffraction of METIS coronagraph external occulter

Romoli

Landini

Moses

et al. 2017

International Conference on Space Optics — ICSO 2012

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Abstract-METIS (Multi Element Telescope for Imaging andSpectroscopy) is an externally occulted coronagraph part of the Solar Orbiter payload. METIS innovative occulting system, called inverted externally occulter (IEO), consists of a circular aperture, IEO, that acts also as the entrance pupil of the instrument, and a solar disk rejection mirror (M0), placed at the bottom end of the coronagraph boom. M0 reflects back through IEO the solar disk radiation, letting the coronal radiation enter the coronagraph telescope. Light diffracted by IEO enters the telescope and has to be minimized with a proper shape of the IEO edge. The paper describes the theoretical results of the diffraction analysis extended to the scattered light by the primary mirror of the telescope onto the primary focal plane. A summary of the entire stray light reduction capabilities of METIS is also given.

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“…z$ (rad). (11) The accuracy in deriving the rotation angle depends on the SNR of the polarization measurement: LP 1 1 (12) By combining these two expressions and by making use of Eq. 6, the accuracy in deriving of the fled can be expressed in terms of instrumental and observational characteristics: At heliocentric distance 1.3 R®, the expected coronal field is B = 2 gauss, and the degree of line polarization is P '-0.1.…”

Section: Sensitivity To Coronal Magnetic Fieldsmentioning

confidence: 99%

<title>Polarimetry of the UV solar corona with ASCE</title>

et al. 1999

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The Advanced Solar Coronal Explorer (ASCE) is a mid-explorer (MidEx) mission selected, together with other five, for the a Phase A Concept Study in the 1999 round of MidEx proposal. ASCE's spacecraft bus is a SPARTAN 400 reusable carrier deployed in low Earth orbit by the Space Shuttle. ASCE's payload comprises two instrument modules, the Spectroscopic and Polarimetric Coronagraph (SPC) and the Extreme Ultravoilet Imager (EUVI). The scientific objective of the mission is the investigation, through spectroscopic and polarimetric techniques, of the physics of the coronal heating and of the solar wind acceleration. A critical physical parameter of the corona is the magnetic field. Polarimetric measurements of UV coronal radiation and their interpretation through the Hanle effect can be used for coronal magnetic field diagnostics. One of the SPC spectrometers, the Spectroscopy/Polarimetry channel (SPCH), includes a reflecting Brewster-angle polarimeter for measurements of the linear polarization of the HI Lyman series lines (i.e., Ly-a, -3, and -y) and of the 0 VI 1032 A line. In this paper, the optical design of the SPCH polarimeter is described. A relevant element of this design is the external occulter (EXO) that is supported on a boom, which is extended 10 m beyond the instrument aperture, once the instrument is in station. The analysis of the stray-light reduction provided by this occulting system is described in this paper. The principal source of stray light is solar disk light that is diffracted from the edge of the EXO and scattered from the telescope mirror. The analysis shows that the stray-light is < 10_2 the coronal signal. This level of stray-light rejection minimizes the polarized stray light that may be introduced by the EXO's straight edge. The most appropriate material for the polarizer has been found to be CaF2 . The material selection criteria are described. Finally, the paper illustrates with an example that if the linear polarization can be measured better than 1%, then the instrumental sensitivity to magnetic fields may reach a few gauss (> 2 gauss), in coronal active regions.

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<title>Stray light analysis of a reflecting UV Coronagraph/Polarimeter with multilayer optics</title>

Cited by 9 publications

References 0 publications

Stray-light analyses of the multielement telescope for imaging and spectroscopy coronagraph on Solar Orbiter

Stray-light analyses of the multielement telescope for imaging and spectroscopy coronagraph on Solar Orbiter

Evaluation of the stray light from the diffraction of METIS coronagraph external occulter

<title>Polarimetry of the UV solar corona with ASCE</title>

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