The space coronagraph optical bench (SCoOB): 2. Wavefront sensing and control in a vacuum-compatible coronagraph testbed for spaceborne high-contrast imaging technology

Gorkom, Kyle Van; Douglas, Ewan S.; Ashcraft, Jaren N.; Haffert, Sebastiaan Y.; Kim, Daewook; Choi, Heejoo; Anche, Ramya M.; Males, Jared R.; Milani, Kian; Derby, Kevin; Harrison, Lori; Durney, Olivier

doi:10.1117/12.2630704

Cited by 7 publications

(9 citation statements)

References 14 publications

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“…In order to reach deeper contrasts we employ wavefront sensing and control techniques suitable for high-contrast imaging. A more comprehensive review of the implementation and results of these efforts are outlined in Van Gorkom et al, 17 but a brief introduction to current efforts is written here.…”

Section: First Light Resultsmentioning

confidence: 99%

“…Recently the SCC Lyot stop has been installed, and we will be conducting tests of dark hole stability under SCC control in the near future. To learn about our wavefront sensing and control efforts in detail, see the accompanying proceedings by Van Gorkom et al 17 A candidate future realization of SCoOB includes two deformable mirrors (Fig 9) to correct for amplitude errors from pupil segmentation. 25 A list of the hardware used in this testbed is included in the appendix after the references.…”

Section: Discussionmentioning

confidence: 99%

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The Space Coronagraph Optical Bench (SCoOB): 1. Design and Assembly of a Vacuum-compatible Coronagraph Testbed for Spaceborne High-Contrast Imaging Technology

Ashcraft¹,

Choi²,

Douglas³

et al. 2022

Preprint

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The development of spaceborne coronagraphic technology is of paramount importance to the detection of habitable exoplanets in visible light. In space, coronagraphs are able to bypass the limitations imposed by the atmosphere to reach deeper contrasts and detect faint companions close to their host star. To effectively test this technology in a flight-like environment, a high-contrast imaging testbed must be designed for operation in a thermal vacuum (TVAC) chamber. A TVAC-compatible high-contrast imaging testbed is undergoing development at the University of Arizona inspired by a previous mission concept: The Coronagraphic Debris and Exoplanet Exploring Payload (CDEEP). The testbed currently operates at visible wavelengths and features a Boston Micromachines Kilo-C DM for wavefront control. Both a vector vortex coronagraph and a knife-edge Lyot coronagraph operating mode are under test. The optics will be mounted to a 1 x 2 meter pneumatically isolated optical bench designed to operate at 10 −8 torr and achieve raw contrasts of 10 −8 or better. The validation of our optical surface quality, alignment procedure, and first light results are presented. We also report on the status of the testbed's integration in the vaccum chamber.

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Section: First Light Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Space Coronagraph Optical Bench (SCoOB): 1. Design and Assembly of a Vacuum-compatible Coronagraph Testbed for Spaceborne High-Contrast Imaging Technology

Ashcraft¹,

Choi²,

Douglas³

et al. 2022

Preprint

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“…This is a major advantage for ground-based systems that usually have more optics than their space-based counterpart. The ease of implementation is readily shown because iEFC has already been implemented on several other benches with different coronagraph architectures such as SCExAO that uses the Classic Lyot Coronagraph at H-band (Ahn et al 2021(Ahn et al , 2023 and the Space Coronagraph Optical Bench (SCoOB) (Ashcraft et al 2022;Van Gorkom et al 2022) at Steward observatory which uses the knife-edge PAPLC and VVC.…”

Section: Discussionmentioning

confidence: 99%

Implicit electric field conjugation: Data-driven focal plane control

Haffert¹,

Males²,

Ahn³

et al. 2023

A&A

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Context. Direct imaging of Earth-like planets is one of the main science cases for the next generation of extremely large telescopes. This is very challenging due to the star-planet contrast that has to be overcome. Most current high-contrast imaging instruments are limited in sensitivity at small angular separations due to non-common path aberrations (NCPA). The NCPA leak through the coronagraph and create bright speckles that limit the on-sky contrast and therefore also the post-processed contrast. Aims. We aim to remove the NCPA by active focal plane wavefront control using a data-driven approach. Methods. We developed a new approach to dark hole creation and maintenance that does not require an instrument model. This new approach is called implicit Electric Field Conjugation (iEFC) and it can be empirically calibrated. This makes it robust for complex instruments where optical models might be difficult to realize. Numerical simulations have been used to explore the performance of iEFC for different coronagraphs. The method was validated on the internal source of the Magellan Adaptive Optics eXtreme (MagAO-X) instrument to demonstrate iEFC's performance on a real instrument. Results. Numerical experiments demonstrate that iEFC can achieve deep contrast below 10 −9 with several coronagraphs. The method is easily extended to broadband measurements and the simulations show that a bandwidth up to 40% can be handled without problems. Lab experiments with MagAO-X showed a contrast gain of a factor 10 in a broadband light and a factor 20 to 200 in narrowband light. A contrast of 5 • 10 −8 was achieved with the Phase Apodized Pupil Lyot Coronagraph at 7.5 λ/D. Conclusions. The new iEFC method has been demonstrated to work in numerical and lab experiments. It is a method that can be empirically calibrated and it can achieve deep contrast. This makes it a valuable approach for complex ground-based high-contrast imaging systems.

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“…Future observatories will be equipped with advanced coronagraphs with the goal of reaching 10 -10 or higher contrast to survey large populations of exoplanets and search for signatures of life. Currently, 10 -8 to 10 -10 contrasts have been demonstrated in laboratory settings, [7][8][9][10][11] but significant work is needed to translate these to observatory operation. Even as contrasts dive deeper, limited photon flux remains a fundamental constraint when trying to detect small exoplanets.…”

Section: Introductionmentioning

confidence: 99%

Integrated modeling of wavefront sensing and control for space telescopes utilizing active and adaptive optics

Derby,

Milani,

Blomquist

et al. 2023

Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems IV

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Extreme wavefront correction is required for coronagraphs on future space telescopes to reach 10 -8 or better starlight suppression for the direct imaging and characterization of exoplanets in reflected light. Thus, a suite of wavefront sensors working in tandem with active and adaptive optics are used to achieve stable, nanometerlevel wavefront control over long observations. In order to verify wavefront control systems, comprehensive and accurate integrated models are needed. These should account for any sources of on-orbit error that may degrade performance past the limit imposed by photon noise.An integrated model of wavefront sensing and control for a space-based coronagraph was created using geometrical raytracing and physical optics propagation methods. Our model concept consists of an active telescope front end in addition to a charge-6 vector vortex coronagraph instrument. The telescope uses phase retrieval to guide primary mirror bending modes and secondary mirror position to control the wavefront error within tens of nanometers. The telescope model is dependent on raytracing to simulate these active optics corrections for compensating the wavefront errors caused by misalignments and thermal gradients in optical components. Entering the coronagraph, a self-coherent camera is used for focal plane wavefront sensing and digging the dark hole. We utilize physical optics propagation to model the coronagraphy's sensitivity to mid and high-order wavefront errors caused by optical surface errors and pointing jitter. We use our integrated models to quantify expected starlight suppression versus wavefront sensor signal-to-noise ratio.

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The space coronagraph optical bench (SCoOB): 2. Wavefront sensing and control in a vacuum-compatible coronagraph testbed for spaceborne high-contrast imaging technology

Cited by 7 publications

References 14 publications

The Space Coronagraph Optical Bench (SCoOB): 1. Design and Assembly of a Vacuum-compatible Coronagraph Testbed for Spaceborne High-Contrast Imaging Technology

The Space Coronagraph Optical Bench (SCoOB): 1. Design and Assembly of a Vacuum-compatible Coronagraph Testbed for Spaceborne High-Contrast Imaging Technology

Implicit electric field conjugation: Data-driven focal plane control

Integrated modeling of wavefront sensing and control for space telescopes utilizing active and adaptive optics

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