Dark hole maintenance with modal pairwise probing in numerical simulations of Roman coronagraph instrument

Future planned space telescopes, such as the IR/O/UV Large Telescope, recommended by Astro2020 will be used to directly image exo-Earths. They will employ high-order wavefront sensing and control (HOWFSC) to correct static and slow wavefront errors in the image plane to achieve contrasts better than 10 9 . Our work evaluates the computational requirements for HOWFSC algorithms and compares these to the capabilities of processors that are expected to be available during mission development. We find that HOWFSC creates unprecedented requirements for space-based computational power, such as the ∼10 13 floating-point operations necessary to generate the dark hole, based on the Large UV/Optical/IR (LUVOIR) study. In our worst-case estimates, maintaining an LUVOIR-size dark hole at 10 10 contrast might require up to several orders of magnitude more computational throughput than available on the most advanced radiation-hardened processor.

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“…5.2). Both more time-efficient versions of EFC 21 and slower but more contrast-optimal versions 67 have been proposed.…”

Section: Discussionmentioning

confidence: 99%

Computational complexities of image plane algorithms for high contrast imaging in space telescopes

Pogorelyuk

Haughwout

Belsten

et al. 2022

J. Astron. Telesc. Instrum. Syst.

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“…In addition to science simulations, the OS9 results have provided the basis for an exploration 104 of alternative methods of dark hole maintenance that do not require repeated visits to the reference star and instead rely on modulations of the DM patterns.…”

Section: Stability and Structural Thermal And Optical Performance Mod...mentioning

confidence: 99%

End-to-end numerical modeling of the Roman Space Telescope coronagraph

Krist,

Steeves,

Dube

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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The Roman Space Telescope will have the first advanced coronagraph in space, with deformable mirrors (DMs) for wavefront control (WFC), low-order wavefront sensing and maintenance, and a photon-counting detector. It is expected to be able to detect and characterize mature, giant exoplanets in reflected visible light. Over the past decade, the performance of the coronagraph in its flight environment has been simulated with increasingly detailed diffraction and structural/thermal finite-element modeling. With the instrument now being integrated in preparation for launch within the next few years, the present state of the end-to-end modeling, including the measured flight components such as DMs, is described. The coronagraphic modes, including characteristics most readily derived from modeling, are thoroughly described. The methods for diffraction propagation, WFC, and structural and thermal finite-element modeling are detailed. The techniques and procedures developed for the instrument will serve as a foundation for future coronagraphic missions, such as the Habitable Worlds Observatory.

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“…If the coronagraph can maintain the dark hole contrast without the need to point to a bright star, this capability will significantly improve science yield, reduce required observing time, and lower costs. 8 Even in situations where the target star is bright enough, the use of traditional PWP interrupts the science acquisitions. Another advantage of dark hole maintenance techniques is the potential to relax wavefront stability requirements.…”

Section: Introductionmentioning

confidence: 99%

Experimental demonstration of spectral linear dark field control at NASA’s high contrast imaging testbeds

Poon,

Potier,

Ruane

et al. 2023

Techniques and Instrumentation for Detection of Exoplanets XI

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In order to directly image Earth-like exoplanets (exoEarths) orbiting Sun-like stars, the Habitable Worlds Observatory coronagraph instrument(s) will be required to suppress the starlight to raw contrasts of approximately 10−10 . Coronagraphs use active methods of Wavefront Sensing and Control (WFSC) such as Pairwise Probing (PWP) and Electric Field Conjugation (EFC) to create regions of high contrast in the science camera image, called dark holes. Due to the low flux of these exoEarths, long exposure times are required to spectrally characterize them. During these long exposures, the optical system will drift resulting in degradation of the contrast over time. To prevent such contrast drift, a WFSC algorithm running in parallel to the science acquisition can stabilize the contrast in the dark hole. However, PWP cannot be reused to efficiently stabilize the contrast since it relies on strong temporal modulation of the intensity in the image plane that would interrupt the science acquisition. Conversely, spectral Linear Dark Field Control (LDFC) takes advantage of the linear relationship between the change in intensity of the post-coronagraph out-of-band image and small changes in wavefront to preserve the dark hole region during science exposures. In this paper, we show experimental results that demonstrate spectral LDFC stabilizes the contrast to levels of a few 10−9 on a Lyot coronagraph testbed which is housed in a vacuum chamber. Promising results show that spectral LDFC is able to correct for disturbances that degrade the contrast by more than 100×. To our knowledge, this is the first experimental demonstration of spectral LDFC and the first demonstration of spatial or spectral LDFC on a vacuum coronagraph testbed and at contrast levels less than 10−8 .

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Dark hole maintenance with modal pairwise probing in numerical simulations of Roman coronagraph instrument

Cited by 3 publications

References 29 publications

Computational complexities of image plane algorithms for high contrast imaging in space telescopes

Computational complexities of image plane algorithms for high contrast imaging in space telescopes

End-to-end numerical modeling of the Roman Space Telescope coronagraph

Experimental demonstration of spectral linear dark field control at NASA’s high contrast imaging testbeds

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