Effects of space telescope primary mirror segment errors on coronagraph instrument performance

Nemati, Bijan; Stahl, Mark T.; Stahl, Phil

doi:10.1117/12.2273072

Cited by 16 publications

(22 citation statements)

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“…Finally, these rigorously derived analytical results are similar to and consistent with our previously published numerical simulation results. [11][12][13][14][15] Also note that the allocation between modes can be further refined on a case-by-case basis depending upon which modes are mostly likely to occur in a given telescope implementation.…”

Section: Linking the Error Budget To Requirements On Wavefront Stabilitymentioning

confidence: 99%

“…11 And the tolerable amplitude depends on the coronagraph's sensitivity to that error, as well as the error mode's spatial and temporal characteristics. [11][12][13][14][15][16][17][18] References 11-18 each calculated candidate coronagraph's contrast leakage as a function of wavefront error mode. References 11-15 used numerical simulations to calculate contrast leakage for Seidel aberrations and segmented aperture piston and tip/tilt error.…”

Section: Introductionmentioning

confidence: 99%

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Method for deriving optical telescope performance specifications for Earth-detecting coronagraphs

Nemati

Stahl

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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Direct detection and characterization of extrasolar planets has become possible with powerful new coronagraphs on ground-based telescopes. Space telescopes with active optics and coronagraphs will expand the frontier to imaging Earth-sized planets in the habitable zones of nearby Sun-like stars. Currently, NASA is studying potential space missions to detect and characterize such planets, which are dimmer than their host stars by a factor of 10 10. One approach is to use a star-shade occulter. Another is to use an internal coronagraph. The advantages of a coronagraph are its greater targeting versatility and higher technology readiness, but one disadvantage is its need for an ultrastable wavefront when operated open-loop. Achieving this requires a system-engineering approach, which specifies and designs the telescope and coronagraph as an integrated system. We describe a systems engineering process for deriving a wavefront stability error budget for any potential telescope/coronagraph combination. The first step is to calculate a given coronagraph's basic performance metrics, such as contrast. The second step is to calculate the sensitivity of that coronagraph's performance to its telescope's wavefront stability. The utility of the method is demonstrated by intercomparing the ability of several monolithic and segmented telescope and coronagraph combinations to detect an exo-Earth at 10 pc. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Linking the Error Budget To Requirements On Wavefront Stabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Method for deriving optical telescope performance specifications for Earth-detecting coronagraphs

Nemati

Stahl

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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“…[44][45][46][47] Studies performing Monte Carlo (MC) end-to-end (E2E) simulations 48,49 have confirmed the strict WFE requirements of a couple of tens of picometers over tens of minutes to enable the search for faint extra-solar planets, and analytical methods for the derivation of coronagraphic performance specifications have been proposed. 50,51 One thing that all of these studies have in common is that they define global WFE tolerances over the entire telescope pupil, where the segments have a random contribution to the overall aberrations. In this paper, we focus on analytically defining requirements on a segment-tosegment basis instead, using the Pair-based Analytical model for Segmented Telescope Imaging from Space (PASTIS), [52][53][54] which models the DH average contrast of a coronagraph on a segmented telescope as a function of the segment aberrations.…”

Section: Introductionmentioning

confidence: 99%

Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging

Laginja

Soummer

Mugnier

et al. 2021

J. Astron. Telesc. Instrum. Syst.

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This paper introduces an analytical method to calculate segment-level wavefront error (WFE) tolerances to enable the detection of faint extra-solar planets using segmentedaperture telescopes in space. This study provides a full treatment of the case of spatially uncorrelated segment phasing errors for segmented telescope coronagraphy, which has so far only been approached using ad-hoc Monte Carlo (MC) simulations. Instead of describing the wavefront tolerance globally for all segments, our method produces spatially dependent requirement maps. We relate the statistical mean contrast in the coronagraph dark hole to the standard deviation of the WFE of each individual segment on the primary mirror. This statistical framework for segment-level tolerancing extends the Pair-based Analytical model for Segmented Telescope Imaging from Space (PASTIS), which is based uniquely on a matrix multiplication for the optical propagation. We confirm our analytical results with MC simulations of end-to-end optical propagations through a coronagraph. Comparing our results for the Apodized Pupil Lyot Coronagraph designs for the Large Ultraviolet Optical Infrared telescope to previous studies, we show general agreement but we provide a relaxation of the requirements for a significant subset of segments in the pupil. These requirement maps are unique to any given telescope geometry and coronagraph design. The spatially uncorrelated segment tolerances we calculate are a key element of a complete error budget that will also need to include allocations for correlated segment contributions. We discuss how the PASTIS formalism can be extended to the spatially correlated case by deriving the statistical mean contrast and its variance for a nondiagonal aberration covariance matrix. The PASTIS tolerancing framework therefore brings a new capability that is necessary for the global tolerancing of future segmented space observatories.

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“…Resolving an Earth-like planet near a Sun-like star with a telescope requires instruments that are able to image at extremely high contrasts of 10-10 [12]. Achieving this contrast level with a coronagraph instrument, which blocks out the light of the target star so the dim companion planet is visible, requires an adaptive optics system capable of picometer-level wavefront control [13]. Deformable mirrors can be used in coronagraph systems to control the wavefront in order to prevent speckles and stray light from degrading the contrast [13,14,15].…”

Section: Introductionmentioning

confidence: 99%

“…Achieving this contrast level with a coronagraph instrument, which blocks out the light of the target star so the dim companion planet is visible, requires an adaptive optics system capable of picometer-level wavefront control [13]. Deformable mirrors can be used in coronagraph systems to control the wavefront in order to prevent speckles and stray light from degrading the contrast [13,14,15]. Picometer-level control has been demonstrated at the NASA Jet Propulsion Laboratory (JPL) High Contrast Imaging Testbed [16].…”

Section: Introductionmentioning

confidence: 99%

MEMS Deformable Mirrors for Space-Based High-Contrast Imaging

et al. 2019

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Micro-Electro-Mechanical Systems (MEMS) Deformable Mirrors (DMs) enable precise wavefront control for optical systems. This technology can be used to meet the extreme wavefront control requirements for high contrast imaging of exoplanets with coronagraph instruments. MEMS DM technology is being demonstrated and developed in preparation for future exoplanet high contrast imaging space telescopes, including the Wide Field Infrared Survey Telescope (WFIRST) mission which supported the development of a 2040 actuator MEMS DM. In this paper, we discuss ground testing results and several projects which demonstrate the operation of MEMS DMs in the space environment. The missions include the Planet Imaging Concept Testbed Using a Recoverable Experiment (PICTURE) sounding rocket (launched 2011), the Planet Imaging Coronagraphic Technology Using a Reconfigurable Experimental Base (PICTURE-B) sounding rocket (launched 2015), the Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) high altitude balloon (expected launch 2019), the High Contrast Imaging Balloon System (HiCIBaS) high altitude balloon (launched 2018), and the Deformable Mirror Demonstration Mission (DeMi) CubeSat mission (expected launch late 2019). We summarize results from the previously flown missions and objectives for the missions that are next on the pad. PICTURE had technical difficulties with the sounding rocket telemetry system. PICTURE-B demonstrated functionality at >100 km altitude after the payload experienced 12-g RMS (Vehicle Level 2) test and sounding rocket launch loads. The PICTURE-C balloon aims to demonstrate 10 - 7 contrast using a vector vortex coronagraph, image plane wavefront sensor, and a 952 actuator MEMS DM. The HiClBaS flight experienced a DM cabling issue, but the 37-segment hexagonal piston-tip-tilt DM is operational post-flight. The DeMi mission aims to demonstrate wavefront control to a precision of less than 100 nm RMS in space with a 140 actuator MEMS DM.

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Effects of space telescope primary mirror segment errors on coronagraph instrument performance

Cited by 16 publications

References 1 publication

Method for deriving optical telescope performance specifications for Earth-detecting coronagraphs

Method for deriving optical telescope performance specifications for Earth-detecting coronagraphs

Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging

MEMS Deformable Mirrors for Space-Based High-Contrast Imaging

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