Optical performance for the James Webb Space Telescope

Lightsey, Paul A.; Barto, Allison; Contreras, James

doi:10.1117/12.550091

Cited by 22 publications

(9 citation statements)

References 2 publications

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“…Pessimistic estimates of thermal instabilities induced by slewing JWST from its coldest to its warmest attitudes are included in the JWST Project's Rev-T wavefront error models. 21,[23][24][25] Numerical estimates of binary point source contrast using closure phases and squared visibilities with a two day interval between the calibrator and target, and the models' worst-case thermal drift of JWST's structure, indicate a contrast of 12 magnitudes between 75 to 450 mas is achievable under these assumptions. Thus thermal drifts of the telescope wavefront are not expected to be significant obstacles to acheiving scientifically interesting contrast.…”

Section: Niriss Ami and Future Space-based Nrmmentioning

confidence: 96%

Non-redundant Aperture Masking Interferometry (AMI) and segment phasing with JWST-NIRISS

Sivaramakrishnan

Lafrenière

Ford

et al. 2012

Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave

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The Aperture Masked Interferometry (AMI) mode on JWST-NIRISS is implemented as a 7-hole, 15% throughput, non-redundant mask (NRM) that operates with 5-8% bandwidth filters at 3.8, 4.3, and 4.8 microns. We present refined estimates of AMI's expected point-source contrast, using realizations of noise matched to JWST pointing requirements, NIRISS detector noise, and Rev-V JWST wavefront error models for the telescope and instrument. We describe our point-source binary data reduction algorithm, which we use as a standardized method to compare different observational strategies. For a 7.5 magnitude star we report a 10-σ detection at between 8.7 and 9.2 magnitudes of contrast between 100 mas to 400 mas respectively, using closure phases and squared visibilities in the absence of bad pixels, but with various other noise sources. With 3% of the pixels unusable, the expected contrast drops by about 0.5 magnitudes. AMI should be able to reach targets as bright as M=5. There will be significant overlap between Gemini-GPI and ESO-SPHERE targets and AMI's search space, and a complementarity with NIRCam's coronagraph. We also illustrate synthesis imaging with AMI, demonstrating an imaging dynamic range of 25 at 100 mas scales. We tailor existing radio interferometric methods to retrieve a faint bar across a bright nucleus, and explain the similarities to synthesis imaging at radio wavelengths. Modest contrast observations of dusty accretion flows around AGNs will be feasible for NIRISS AMI. We show our early results of image-plane deconvolution as well. Finally, we report progress on an NRM-inspired approach to

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Section: Niriss Ami and Future Space-based Nrmmentioning

confidence: 96%

Non-redundant Aperture Masking Interferometry (AMI) and segment phasing with JWST-NIRISS

Sivaramakrishnan

Lafrenière

Ford

et al. 2012

Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave

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“…IM mainly supported JWST Missions Systems Engineering for verification of the Technical Performance Metrics (TPMs) of the Image Quality (IQ) and Environmental requirements. The IQ requirements were presented in section 1.1, and are the basis for lower-level requirements and allocations captured in the error budgets presented in section 1.2 (thermal and vibration impacts to alignment stability, wavefront stability and image motion), as well as performance aspects not addressed in this paper, including the much larger shifts in alignment as the telescope cools down from ambient to cold temperatures, and the quasi-static wavefront shifts resulting from periodic wavefront sensing and control corrections 14 . The Sensitivity requirement is the basis for allocations to radiometric performance, stray light suppression and detector performance.…”

Section: The Role Of Integrated Modelingmentioning

confidence: 99%

Integrated modeling of the James Webb Space Telescope: pre-launch predictions, flight performance, and lessons learned

Levine-West,

Mosier,

Walsh

et al. 2023

Optical Modeling and Performance Predictions XIII

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Because of its size and complexity, the Observatory performance of the James Webb Space Telescope (JWST) in its operating condition was primarily verified by analysis prior to launch, breaking the standard NASA paradigm of test-asyou-fly. Most of the requisite analytical predictions were achieved through Integrated Modeling which combines models of the various physics and subsystem behaviors affecting system-level performance: thermal, jitter, structures thermal distortion, gravity release and alignments, optics, wavefront sensing and control, attitude control, straylight and launch loads analysis. We will briefly describe the process by which models were managed, constructed, verified, validated, and used to support the analyses. We will address how uncertainties were accounted for given the many unknowns of the nanometric performance of the first-of-its-kind large deployable cryogenic precision optics in space. Finally, we will compare the pre-flight predictions to actual performance on-orbit for several key analysis use cases and conclude with lessons learned for future missions.The term "jitter" is often synonymous with high-frequency, uncompensated contributions to line-of-sight (LOS) stability or image motion. For the James Webb Space Telescope (JWST) mission, this working definition was extended to include dynamic contributions to wavefront error (WFE). Pre-launch verification of on-orbit jitter performance was not possible via testing, therefore high-fidelity end-to-end modeling was needed for credible verification-by-analysis. The jitter analysis was a main thrust of the overall JWST Integrated Modeling effort and was supported by a robust model verification and validation activities. Following launch, during the latter stages of the 6-month commissioning phase, LOS measurements were obtained and compared to the pre-launch predictions, then to a set of revised predictions. Here we present the modeling methodology supporting the jitter analysis, the pre-and post-launch analysis results, the comparison with the flight data, and conclusions drawn from this comparison.

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“…These OPDs, 2 provided with the JWPSF 3 software distribution, represent the wavefront in the NIRCam short-wavelength channel assuming low-, mid-, and high-spatial frequency wavefront error allocations to the Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM), as defined by "Revision T" of the the JWST optical error budget. 4 The OPDs themselves are presented in physical units (microns), allowing for a single OPD to be used for analyses at several different wavelengths (see Fig. 1).…”

Section: Optical Path Difference Modelsmentioning

confidence: 99%

Towards observing extrasolar giant-planet environments with JWST

Makidon

Sivaramakrishnan

Soummer

et al. 2008

Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter

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With its high Strehl ratio near-and mid-infrared imaging capabilities, wide field of view, and multiple spectroscopic options, the James Webb Space Telescope (JWST) will provide crucial information on the circumstellar environments of stars thought to harbor debris disks, brown dwarfs or extrasolar giant planets. However, the successful study of such faint targets around nearby, bright stars requires the effective removal of the target star's contribution from the image. In this work, we use simple models of the temporal behavior JWST's wavefront error of JWST over time to examine whether frequent measurements of that changing wavefront can be used to provide an effective point spread function subtraction for high-contrast imaging studies without use of coronagraphic techniques.

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Optical performance for the James Webb Space Telescope

Cited by 22 publications

References 2 publications

Non-redundant Aperture Masking Interferometry (AMI) and segment phasing with JWST-NIRISS

Non-redundant Aperture Masking Interferometry (AMI) and segment phasing with JWST-NIRISS

Integrated modeling of the James Webb Space Telescope: pre-launch predictions, flight performance, and lessons learned

Towards observing extrasolar giant-planet environments with JWST

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