TRL-6 for JWST wavefront sensing and control

Feinberg, Lee; Dean, Bruce H.; Aronstein, David L.; Bowers, Charles W.; Hayden, William L.; Lyon, Richard G.; Shiri, Ron; Smith, Jeffrey S.; Acton, D. Scott; Carey, Larkin; Contos, Adam R.; Sabatke, Erin; Schwenker, John P.; Shields, Duncan M.; Towell, Tim; Shi, Fang; Meza, Luis

doi:10.1117/12.736059

Cited by 33 publications

(15 citation statements)

References 24 publications

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“…The dispersed Hartman coarse phasing process was demonstrated on the Keck telescope (Albanese 2006). The overall flight wavefront sensing and control process has been demonstrated on a 1/6 scale fully functional model (Figure 7) of the JWST telescope (Feinberg 2007, Contos 2008). …”

Section: Collecting the First Lightmentioning

confidence: 98%

The JWST science instrument payload: mission context and status

Greenhouse

2014

SPIE Proceedings

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The James Webb Space Telescope (JWST) is the scientific successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 m 2 aperture (6 m class) telescope that will achieve diffraction limited angular resolution at a wavelength of 2 um. The science instrument payload includes four passively cooled near-infrared instruments providing broad-and narrow-band imagery, coronography, as well as multi-object and integral-field spectroscopy over the 0.6 < λ < 5.0 um spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronography, and integral-field spectroscopy over the 5.0 < λ < 29 um spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations to be proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete. Construction, integration and verification testing is underway in all areas of the program. The JWST is on schedule for launch during 2018. This science case forms the basis from which detailed science and mission requirements were derived to guide engineering design and development of the JWST as a research tool. The science observations that are implemented by the JWST will be proposed by the international astronomical community in response to annual peer reviewed proposal opportunities (Rigby 2012). The discovery potential of the JWST relative to other concurrent facilities is discussed in Thronson, Stiavelli, and Tielens 2009. The emergence of the first sources of light in the universe marks the end of the "Dark Ages" in cosmic history (Rees 1997). The ultraviolet radiation field produced by these sources created the ionization that is observed in the local intergalactic medium (IGM). The JWST design provides unique capability to address key questions about this era in cosmic evolution including: what is the nature of the first galaxies; how and when did ionization of the space between them occur; and what sources caused the ionization? The JWST architecture is primarily shaped by requirements associated with answering the above questions.In contrast to the Hubble Space Telescope (HST), the JWST is designed as an infrared optimized telescope to observe the redshifted visible and ultraviolet radiation from the first galaxies and supernovae of the first stars. To achieve the nJy sensitivity needed to observe this era (z ~ 6-20), the observatory must have a telescope aperture that is larger in diameter than the largest rocket faring, and the entire optical system must be cooled to ~40-50 K. Finally, the resulting large deployable cryogenic telescope must achieve HST-like angular resolution, but at a 4X longer wavelength thus, also necessitating a large diameter telescope aperture. The major observatory design features (Table 1, Figure 1) trace directly from these requirements and differ markedly from those of the HST.

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Section: Collecting the First Lightmentioning

confidence: 98%

The JWST science instrument payload: mission context and status

Greenhouse

2014

SPIE Proceedings

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“…WFS&C Commissioning process validation is anchored in the Technology Readiness Level 6 (TRL-6) demonstration testing performed on the TBT in 2006 [5] . The TBT is being used for additional commissioning run-throughs, including those that further stress the process limits.…”

Section: Testbed Telescopementioning

confidence: 99%

Verification of the James Webb Space Telescope (JWST) wavefront sensing and control system

Contos¹,

Acton²,

Barto³

et al. 2008

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

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From its orbit around the Earth-Sun second Lagrange point some million miles from Earth, the James Webb Space Telescope (JWST) will be uniquely suited to study early galaxy and star formation with its suite of infrared instruments. [1] To maintain exceptional image quality using its 6.6 meter segmented primary mirror, wavefront sensing and control (WFS&C) is vital to ensure the optical alignment of the telescope throughout the mission. After deployment of the observatory structure and mirrors from the "folded" launch configuration, WFS&C is used to align the telescope [2] , as well as maintain that alignment. WFS&C verification includes the verification of the software and its incorporated algorithms, along with the supporting aspects of the integrated ground segment, instrumentation, and telescope through increasing levels of assembly. The software and process are verified with the Integrated Telescope Model (ITM), which is a Matlab/Simulink integrated observatory model which interfaces to CodeV/OSLO/IDL. In addition to lower level testing, the Near-Infrared Camera [3] (NIRCam) with its wavefront sensing optical components is verified with the other instruments with a cryogenic optical telescope simulator (OSIM) before moving on to the final WFS&C testing in Chamber A at the Johnson Space Center (JSC) where additional observatory verification occurs.

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“…This technique was used to recover the aberrations of the Hubble Space Telescope [1,2] and has many potential applications, including the alignment of segmented-aperture telescopes such as the James Webb Space Telescope (JWST) [3] or the Thirty Meter Telescope. However, the application of focus-diverse phase retrieval, particularly for segmentedaperture systems, has been limited by the so-called "capture range" problem.…”

Section: Introductionmentioning

confidence: 99%

“…If the starting guess is not close enough to the true phase, the algorithm may stagnate in a local minimum without reaching the true solution. In the initial alignment of a segmented system, the segment tips and tilts may be quite large, putting the system outside of the capture range of phase retrieval; this requires other methods to be employed until the segments are well enough aligned to allow phase retrieval to succeed [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Extended capture range for focus-diverse phase retrieval in segmented aperture systems using geometrical optics

Jurling

Fienup

2014

J. Opt. Soc. Am. A

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Extending previous work by Thurman on wavefront sensing for segmented-aperture systems, we developed an algorithm for estimating segment tips and tilts from multiple point spread functions in different defocused planes. We also developed methods for overcoming two common modes for stagnation in nonlinear optimization-based phase retrieval algorithms for segmented systems. We showed that when used together, these methods largely solve the capture range problem in focus-diverse phase retrieval for segmented systems with large tips and tilts. Monte Carlo simulations produced a rate of success better than 98% for the combined approach.

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TRL-6 for JWST wavefront sensing and control

Cited by 33 publications

References 24 publications

The JWST science instrument payload: mission context and status

The JWST science instrument payload: mission context and status

Verification of the James Webb Space Telescope (JWST) wavefront sensing and control system

Extended capture range for focus-diverse phase retrieval in segmented aperture systems using geometrical optics

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