SPIE O+P 2025 Conference Proceedings Wrap up

The Space Coronagraph Optical Bench (SCoOB): 6. demonstration of Lyot low order wavefront control combined with high order wavefront control using a vortex coronagraph

Kian Milani, Kyle Van Gorkom, Chris B. Mendillo, Ramya Anche, Jaren N. Ashcraft, Kevin Derby, Jared Males, Adam Schilperoort, Ewan S. Douglas

To reach and maintain high contrast levels, coronagraph instruments will require a combination of low-order and high-order wavefront control techniques to correct for dynamic wavefront error. Efficient low-order wavefront sensing and control (LOWFSC) schemes use the starlight rejected by the coronagraph such that LOWFSC can operate with a relatively bright signal to correct rapid disturbances. Meanwhile, a family of high-order wavefront sensing and control (HOWFSC) techniques utilizing the science camera have been developed to create regions of high contrast known as dark holes. These two control loops must operate simultaneously for dark holes to be maintained over long observation periods. Using a 952 actuator MEMS deformable mirror and a vector vortex coronagraph (VVC) on the Space Coronagraph Optical Bench (SCoOB), we demonstrate a Lyot-based LOWFSC loop operating in combination with a HOWFSC loop. For these experiments, implicit electric field conjugation (iEFC) is the chosen HOWFSC technique, and we demonstrate how this empirical method can be calibrated and deployed while the LOWFSC loop corrects for dynamic wavefront error. We show this combination of LOWFSC and iEFC maintained 1E-8 contrast levels in air. https://arxiv.org/abs/2509.02875

The Space Coronagraph Optical Bench (SCoOB): 7. design, fabrication, and first light for a self-coherent camera

The 2020 Decadal Survey on Astronomy and Astrophysics tasked future space observatories with the goal of detecting and characterizing a large sample of Earth-like exoplanets. To achieve this, these observatories will require coronagraphs and wavefront control algorithms in order to achieve 10−10 or better starlight suppression. The Space Coronagraph Optical Bench (SCoOB) is a vacuum compatible testbed at the University of Arizona which aims to advance and mature starlight suppression technologies in a space-like environment. In its current configuration, SCoOB is a charge-6 vector vortex coronagraph outfitted with a Kilo-C microelectromechanical systems deformable mirror capable of achieving sub-10−8 dark hole contrast at visible wavelengths using implicit electric field conjugation (iEFC). In this work, we demonstrate the use of a self-coherent camera (SCC) for dark hole digging and maintenance on SCoOB. The SCC introduces a small off-axis pinhole in the Lyot plane which allows some starlight to reach the focal plane and interfere with residual speckles. This enables high-order focal-plane wavefront sensing which can be combined with active wavefront control to null the speckles in a specified region of high contrast known as the dark hole. We discuss considerations for implementation, potential limitations, and provide a performance comparison with iEFC. We also discuss the design optimization and fabrication process for our SCC Lyot stops. https://arxiv.org/abs/2509.02877

The Space Coronagraph Optical Bench (SCoOB): 8. end-to-end numerical modeling of the testbed to estimate the contrast limits

Ramya M Anche, Kyle Van Gorkom, Kian Milani, Kevin Derby, Emory Jenkins, Jaren Ashcraft, Saraswathi Kalyani Subramanian, Patrick Ingraham, Daewook Kim, Heejoo Choi, Olivier Durney, Ewan Douglas

The space coronagraph optical bench (SCoOB) at the University of Arizona is a high-contrast imaging testbed designed to operate in a vacuum to obtain a contrast better than 1e-8 in optical wavelengths using vector vortex coronagraph (VVC) masks. The testbed performance in a half-sided D-shaped dark hole is 2.2e-9 in a << 1% BW, 4e-9 in a 2% BW, and 2.5e-8 in a 15% BW. While the testbed has met the design specification contrast requirements in monochromatic wavelengths, comprehensive end-to-end numerical modeling to assess contrast limits across different bandpasses has yet to be conducted. In this work, we discuss the results of numerical modeling for the SCoOB testbed in both monochromatic and 10% bandwidths at 525 nm and 630 nm. This modeling incorporates measured VVC retardance, modeled polarization aberrations, measured surface and reflectivity errors, and diffuse and surface reflectivity. We explore and discuss the various factors contributing to the contrast limits. https://arxiv.org/abs/2509.02887

Stages of commissioning alignment for three-mirror anastigmat (TMA) telescopes

Solvay Blomquist, Heejoo Choi, Hyukmo Kang, Hayden Kim, Kevin Derby, Pierre Nicolas, Joanna Rosenbluth, Patrick Ingraham, Ewan S. Douglas, and Daewook Kim

For this study, we present a method for performing an autonomous alignment of a three-mirror anastigmat (TMA) telescope on orbit. The motivation for this study comes from the want to explore options to align the TMA on orbit post-deployment while keeping relative cost to science ratio low. The detector used in the TMA under study provides us with a large field of view (FOV). With a large FOV provided in the design, we can use many stars as sample points to drive this alignment knowing how the average size of the star across the detector changes as a function of moving the secondary mirror (M2). Adjustment of the secondary mirror will happen in a multi-stage procedure, starting with a coarse alignment with a large range of motion, and ending with a finer alignment driven by small, random perturbations of M2. For testing this algorithm, we generate a set of possible misalignment cases of the telescope and test how the multi-stage procedure aligns the telescope from a highly misaligned state to a point at which finer alignment can take over to begin science observations.

Stray and Scattered Light Considerations in a Non-contiguous Array of Commercial CMOS Sensors in a Space Mission

Maggie Y. Kautz, Douglas Kelly, Heejoo Choi, Young Sik Kim, Fernando Coronado, Cameron C. Ard, Patrick Ingraham, Daewook Kim, Ewan S. Douglas

Recent advances in CMOS technology have potential to significantly increase the performance, at low-cost, of an astronomical space telescope. Arrays of sensors in space missions are typically contiguous and act as a monolithic detector. A non-contiguous array, with gaps between individual commercial CMOS detectors, offers potential cost and schedule benefits but poses a unique challenge for stray/scattered light mitigation due to complexities in the optomechanics. For example, if the array of detectors is being fed a large field of view, then each detector will have a different angle of incidence. Any individual bandpass filters need to be held perpendicular to the incoming beam so as not to create variances of central wavelength transmission from detector to detector. It naturally follows that the optical design can force filter ghosts to fall between detectors. When dealing with well-focused, high-intensity beams, first and second order stray light path analyses must be conducted to determine scattered light from glints off of individual optics/opto-mechanics or detector specific vane structures. More mechanical structures are necessary for imaging with non-contiguous arrays, all of which have potential to increase scattered light. This proceeding will document various stray light mitigation strategies for a non-contiguous array of sensors in a space telescope.

Progress toward a demonstration of high contrast imaging at ultraviolet wavelengths

Kyle Van Gorkom, Ramya M. Anche, Christopher B. Mendillo, Jessica Gersh-Range, G.C. Hathaway, Saraswathi Kalyani Subramanian, Justin Hom, Tyler D. Robinson, Mamadou N’Diaye, Nikole K. Lewis, Bruce Macintosh, and Ewan S. Douglas

NASA's Habitable Worlds Observatory (HWO) aims to achieve starlight suppression to the $10^{-10}$ level for the detection and spectral characterization of Earth-like exoplanets. Broadband ozone absorption features are key biosignatures that appear in the 200-400nm near-ultraviolet (UV) regime. Extending coronagraphy from visible wavelengths to the UV, however, brings with it a number of challenges, including tighter requirements on wavefront sensing and control, optical surface quality, scattered light, and polarization aberrations, among other things. We aim to partially quantify and address these challenges with a combination of modeling, high-resolution metrology to the scales required for UV coronagraphy, and—ultimately—a demonstration of UV coronagraphy on the Space Coronagraph Optical Bench (SCoOB) vacuum testbed. In these proceedings, we provide a status update on our modeling and contrast budgeting efforts, characterization efforts to understand performance limitations set by key optical components, and our plans to move toward a demonstration of UV coronagraphy.

Polarization aberration modeling of internal occulters for coronagraphs

Emory L. Jenkins, A J Eldorado Riggs, Ewan S. Douglas, Ramya M. Anche, Dylan M. McKeithen, and Stuart B. Shaklan

The Habitable Worlds Observatory (HWO) coronagraph instrument will need to block starlight so effectively that only one in every $10^{10}$ photons reaching the telescope makes it to the science camera. Otherwise, light from a planet orbiting the star will be buried below the level of the starlight. This is about 100 times the performance of the current generation of space coronagraphs, requiring a significant advancement in starlight rejection. At such extreme contrasts, every optical component must be analyzed for leakage due to imperfections in manufacturing or even the underlying physics that can cause unwanted starlight to reach the science camera. For components with small features, the interaction of the electric and magnetic fields with interfaces of different materials can lead to starlight leakage that may limit performance. This paper considers the Lyot occulter, a small metal dot used by the Lyot family of coronagraph instruments to block the image of a star from reaching the science camera. We use a numerical simulation of Maxwell's equations to estimate the impact of various Lyot occulter geometries on starlight leakage. With these results, we find that starlight leakage from Lyot occulting masks is a non-negligible but mitigatable source of leakage at the required level of performance for the HWO. https://arxiv.org/abs/2508.19397

[End-to-end polarization aberrations simulation for the Decadal Survey Testbed (DST-2)]

Ramya Anche et al.

Design and assembly of the telescope simulator for continuous wavefront sensing and control

Hyukmo Kang et al

Stray light suppression for a large etendue monolithic space telescope

Heejoo Choi et al

Fine alignment and wavefront maintenance of a three-mirror anastigmat using full-field phase retrieval with algorithmic differentiation

Kevin Z. Derby et al.

Wave simulation for diffraction efficiency of an integral field spectrograph

Pierre Nicholas et al.

Methods for determining the blackbody radiation and photon rate for an infrared telescopes

Brian Catanzaro et al.

Characterization of optomechanical joints through lap shear testing

Austin Mears et al.