The JWST/NIRCam coronagraph: mask design and fabrication

Krist, John; Balasubramanian, Kunjithapatham; Beichman, Charles; Echternach, P. M.; Green, Joseph J.; Liewer, K. M.; Muller, Richard E.; Serabyn, Eugene; Shaklan, Stuart; Trauger, John T.; Wilson, Daniel W.; Horner, Scott D.; Mao, Yan; Somerstein, Stephen F.; Vasudevan, Gopal; Kelly, Douglas; Rieke, M. J.

doi:10.1117/12.826448

Cited by 24 publications

(15 citation statements)

References 8 publications

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“…The manufacturing of current apodized pupil Lyot coronagraphs 17,18 for SPHERE 19 and GPI 20 uses the microdot technology, 21,22 and the band-limited coronagraphs of NIRCAM soon to fly aboard JWST have also made use of a similar technique. 23 The demonstrated advantages of microdot apodizers are numerous: 1%-level accuracy on the transmission profile, achromatic in phase and amplitude, and compatibility with a wide range of substrate materials and anti-reflective coatings. Spatial phase distortions are in principle absent, 21,22 but careful control will be necessary for the RAVC.…”

Section: Design Of the Apodizermentioning

confidence: 99%

Demonstration of vortex coronagraph concepts for on-axis telescopes on the Palomar Stellar Double Coronagraph

Mawet¹,

Shelton

Wallace

et al. 2014

SPIE Proceedings

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Here we present preliminary results of the integration of two recently proposed vortex coronagraph (VC) concepts for on-axis telescopes on the Stellar Double Coronagraph (SDC) bench behind PALM-3000, the extreme adaptive optics system of the 200-inch Hale telescope of Palomar observatory. The multi-stage vortex coronagraph (MSVC) uses the ability of the vortex to move light in and out of apertures through multiple VC in series to restore the nominal attenuation capability of the charge 2 vortex regardless of the aperture obscurations. The ring-apodized vortex coronagraph (RAVC) is a one-stage apodizer exploiting the VC Lyot-plane amplitude distribution in order to perfectly null the diffraction from any central obscuration size, and for any vortex topological charge. The RAVC is thus a simple concept that makes the VC immune to diffraction effects of the secondary mirror. It combines a vortex phase mask in the image plane with a single pupil-based amplitude ring apodizer, tailor-made to exploit the unique convolution properties of the VC at the Lyot-stop plane. The prototype apodizer uses the same microdot technology that was used to manufacture the apodized pupil Lyot coronagraph (APLC) equipping SPHERE, GPI and P1640.

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Section: Design Of the Apodizermentioning

confidence: 99%

Demonstration of vortex coronagraph concepts for on-axis telescopes on the Palomar Stellar Double Coronagraph

Mawet¹,

Shelton

Wallace

et al. 2014

SPIE Proceedings

Self Cite

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“…34,35 Note the band-limited coronagraphs of NIRCAM soon to fly aboard JWST have also made use of a similar technique. 36 The demonstrated advantages of microdot apodizers are numerous: 1%-level accuracy on the transmission profile, achromatic in phase and amplitude, compatibility with a wide range of substrate material, and with conventional AR coating. Spatial phase distortion are in principle absent, 34,35 but careful control will be necessary for the RAVC.…”

Section: Apodizing Mask Manufacturingmentioning

confidence: 99%

The multistage and ring-apodized vortex coronagraph: two simple, small-angle coronagraphic solutions for heavily obscured apertures

et al. 2013

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Here we present two simple concepts to make the vortex coronagraph (VC) immune to heavily obscured apertures. The multi-stage VC (MSVC) uses the ability of the vortex to move light in and out of apertures through multiple VC in series to restore the nominal attenuation capability of the charge 2 vortex regardless of the aperture obscurations. The ring-apodized VC (RAVC) is a one-stage apodizer exploiting the VC Lyot-plane amplitude distribution in order to perfectly null the diffraction from any central obscuration size, and for any vortex topological charge. In this paper, we also emphasize the complementarity and similarities of the RAVC to the recently proposed Active Compensation of Aperture Discontinuities (ACAD, L. Pueyo et al. 2013, these proceedings) and more finely optimized shaped-pupil-like apodizations (A. Carlotti et al. 2013, these proceedings). This paper ends with a brief discussion about the trade-offs these techniques offer in the framework of the Extremely Large Telescopes (ELT) and the Astrophysics Focused Telescope Assets (AFTA).

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“…The occulting masks, sized for specific wavelengths chosen to optimize planet detection, will block the central portion of a star's point spread function (PSF) at the JWST telescope focus with different sized spot and wedge-shaped patterns (see Figure 1). The detailed occulting mask design and fabrication have been described by Krist et al 2 The Lyot stops complete the suppression of the stellar PSF by masking any starlight that bypasses the occulters.…”

Section: Introductionmentioning

confidence: 99%

NIRCam coronagraphic Lyot stop: design, fabrication, and testing

et al. 2011

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The NIRCam instrument on the James Webb Space Telescope (JWST) will provide a coronagraphic imaging capability to search for extrasolar planets in the 2-5 microns wavelength range. This capability is realized by a set of Lyot pupil stops with patterns matching the occulting mask located in the JWST intermediate focal plane in the NIRCam optical system. The complex patterns with transparent apertures are made by photolithographic process using a metal coating in the opaque region. The optical density needs to be high for the opaque region, and transmission needs to be high at the aperture. In addition, the Lyot stop needs to operate under cryogenic conditions. We will report on the Lyot stop design, fabrication and testing in this paper.

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The JWST/NIRCam coronagraph: mask design and fabrication

Cited by 24 publications

References 8 publications

Demonstration of vortex coronagraph concepts for on-axis telescopes on the Palomar Stellar Double Coronagraph

Demonstration of vortex coronagraph concepts for on-axis telescopes on the Palomar Stellar Double Coronagraph

The multistage and ring-apodized vortex coronagraph: two simple, small-angle coronagraphic solutions for heavily obscured apertures

NIRCam coronagraphic Lyot stop: design, fabrication, and testing

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