Strategies for high order wavefront sensing and control (HOWFSC) computation on future space telescopes

Belsten, Nicholas; Pogorelyuk, Leonid; Haughwout, Christian; Cady, Eric; Cahoy, Kerri

doi:10.1117/12.2594695

Cited by 6 publications

(6 citation statements)

References 28 publications

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“…Overall, iEFC could be a suitable alternative to EFC for initial contrast improvements since deeper contrasts will require longer exposure times making the calibration of iEFC unfeasible. Future telescopes with larger apertures and greater throughput, such as a 6.5m VVC design for the HWO, 16,17 will also be more suitable for iEFC since exposure times can be reduced to enable more rapid calibrations.…”

Section: Discussionmentioning

confidence: 99%

Simulating the efficacy of the implicit-electric-field-conjugation algorithm for the Roman Coronagraph with noise

Milani,

Douglas,

Haffert

et al. 2023

Techniques and Instrumentation for Detection of Exoplanets XI

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The Roman Coronagraph is expected to perform its High-Order Wavefront Sensing and Control (HOWFSC) with a ground-in-the-loop scheme due to the computational complexity of the Electric-Field-Conjugation (EFC) algorithm. This scheme provides the flexibility to alter the HOWFSC algorithm for given science objectives. A new alternative implicit-EFC algorithm is of particular interest as it requires no optical model to create a dark-hole, making the final contrast independent of the model accuracy. The intended HOWFSC scheme involves running EFC while observing a bright star such as ζ Puppis to create the initial dark-hole, then slew to the science target while maintaining the contrast with low-order WFSC over the given observation. Given a similar scheme, the efficacy of iEFC is simulated for two coronagraph modes, namely the Hybrid Lyot Coronagraph (HLC) and the Wide-Field-of-View Shaped-Pupil-Coronagraph (SPC-WFOV). End-to-end physical optics models for each mode serve as the tool for the simulations. Initial monochromatic simulations are presented and compared with monochromatic EFC results obtained with the FALCO software. Various sets of calibration modes are tested to understand the optimal modes to use when generating an iEFC response matrix. Further iEFC simulations are performed using broadband images with the assumption that ζ Puppis is the stellar object being observed. Shot noise, read noise, and dark current are included in the broadband simulations to determine if iEFC could be a suitable alternative to EFC for the Roman Coronagraph.

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Section: Discussionmentioning

confidence: 99%

Simulating the efficacy of the implicit-electric-field-conjugation algorithm for the Roman Coronagraph with noise

Milani,

Douglas,

Haffert

et al. 2023

Techniques and Instrumentation for Detection of Exoplanets XI

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“…The optical parameters of the on-axis TMA are provided in Daewook et al (2023), 24,25 and the off-axis TMA is provided in Nicholas et al (2023). 26 Both these telescopes are optimized to provide diffractionlimited performance in the optical wavelength regions. The higher-order optical aberrations are present, which are expected to be compensated using wavefront sensing and control.…”

Section: Prt: Optical Layout Incident Angles Reflection Coefficientsmentioning

confidence: 99%

Estimation of polarization aberrations and their effect on the coronagraphic performance for future space telescopes

Anche,

Haffert,

Ashcraft

et al. 2023

Techniques and Instrumentation for Detection of Exoplanets XI

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A major goal of proposed future space observatories, such as the Habitable World Observatory, is to directly image and characterize Earth-like planets around Sun-like stars to search for habitability signatures requiring the starlight suppression (contrast) of 10−10. One of the significant aspects affecting this contrast is the polarization aberrations generated from the reflection from mirror surfaces. The polarization aberrations are the phase-dependent amplitude and phase patterns originating from the Fresnel reflections of the mirror surfaces. These aberrations depend on the angle of incidence and coating parameters of the surface. This paper simulates the polarization aberrations for an on-axis and off-axis TMA telescope of a 6.5 m monolithic primary mirror. We analyze the polarization aberrations and their effect on the coronagraphic performance for eight different recipes of mirror coatings for Astronomical filter bands g-I: three single-layer metal coatings and five recipes of protective coatings. First, the Jones pupils are estimated for each coating and filter band using the polarization ray tracing in Zemax. Then, we propagate these Jones pupils through a Vector Vortex Coronagraph and Perfect Coronagraphs using hcipy, a physical optics-based simulation framework. The analysis shows that the two main polarization aberrations generated from the four mirrors are the retardance-defocus and retardance-tilt. The simulations also show that the coating plays a significant role in determining the strength of the aberrations. The bare/oxi-aluminum and Al+18nm LiF coating outperforms all the other coatings by one order of magnitude.

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“…The RAD5545 has been a primary focus of previous analysis of HOWFSC computation on embedded processors. 13,37 The RTG4 FPGA manufactured by MicroSemi is a radiation tolerant FPGA released in 2015. The device has been tested up to 100s of krad(Si), 38 and is now used in standard spacecraft computing components.…”

Section: Current and Near-future Space Processorsmentioning

confidence: 99%

Evaluating embedded hardware for high-order wavefront sensing and control

Belsten,

Milani,

Pogorelyuk

et al. 2023

Techniques and Instrumentation for Detection of Exoplanets XI

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Future space telescopes such as the Habitable Worlds Observatory (HWO) will use coronagraphs and wavefront control to achieve the approximate 1010 starlight suppression necessary to directly image Earth-like exoplanets. Wavefront control algorithms such as Electric Field Conjugation (EFC) will control thousands of actuators at cadences of seconds or minutes. EFC uses a Jacobian matrix which maps Deformable Mirror (DM) voltages to the change in electric field at the image plane. The Jacobian matrix grows in size with the number of pixels, DM actuators, and spectral channels. EFC on proposed future telescopes like HabEx and LUVOIR will require as much as 25 GFLOPS (floating point operations per second). This level of compute density has never been achieved on radiation-hardened processors that are used on NASA Class-A missions such as the Roman Space Telescope. Previous work has focused on estimating the Compute Density (CD) of processors using assumptions about memory access characteristics and the parallelizability of algorithm implementation. Such analysis produces large uncertainty due to the assumptions necessary to compute CD. To refine the estimates of EFC compute capability of current generation processors, we determine the FLOPS performance of processors using benchmark tests which represent the operations mix and memory access patterns of EFC. The expected EFC iteration computation period on future space telescopes based on application benchmarks is reported. We have created a ray tracing optical model for the telescope assembly as well as a physical optics model for the telescope and coronagraph for the purposes of testing HOWFC algorithms. This testing can be applied to CPUs and FPGAs, representing a range of potential compute architectures.

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Strategies for high order wavefront sensing and control (HOWFSC) computation on future space telescopes

Cited by 6 publications

References 28 publications

Simulating the efficacy of the implicit-electric-field-conjugation algorithm for the Roman Coronagraph with noise

Simulating the efficacy of the implicit-electric-field-conjugation algorithm for the Roman Coronagraph with noise

Estimation of polarization aberrations and their effect on the coronagraphic performance for future space telescopes

Evaluating embedded hardware for high-order wavefront sensing and control

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