Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group

Amplitude variations on a MEMS-based extreme adaptive optics coronagraph testbed

Not Accessible

Your library or personal account may give you access

Abstract

High-contrast imaging techniques such as coronagraphy are expected to play an important role in the imaging of extrasolar planets. Instruments like the Gemini Planet Imager (GPI) or the Spectro- Polar-Imetric High-Contrast Exoplanet Research (SPHERE) require high-dynamic range, achieved using coronagraphs to block light coming from the parent star. An extremely good adaptive optics (AO) system is required to reduce dynamic atmospheric wavefront errors to 50100nm  rms. Systematic wavefront errors must also be controlled at the nanometer-equivalent level to remove persistent speckle artifacts. While precision AO systems can control wavefront phase errors at this level, systematic amplitude or intensity errors can also produce speckle artifacts and are uncontrolled by traditional AO phase conjugation. On the Laboratory for Adaptive Optics (LAO) extreme AO testbed, we observed a discrepancy between the coronagraphic image profile and the profile predicted by simple simulations using the measured optical phase, which could potentially be explained by amplitude variations. Measurements showed up to 7%rms intensity changes across the microelectrical mechanical (MEM) plane of the system. We identified potential sources of amplitude variation and compared them to a Fresnel model of the system. One potential concern was the surface structure of the MEM system’s (MEMS) deformable mirror, but analysis shows that it induces at most 2%  rms variation. The bulk of the observed intensity variation is due to nonuniform illumination of the system by the input single-mode fiber and phase errors mixing into amplitude at the nonpupil-plane due to the Talbot effect, coupled with residual astigmatism in the pupil imager.

© 2009 Optical Society of America

Full Article  |  PDF Article
More Like This
The effect of a small heat source on PSF stability for high-contrast imaging

JuliaW. Evans, Bruce Macintosh, Andrew Norton, Daren Dillon, and Donald Gavel
Opt. Express 17(14) 11652-11664 (2009)

Stroke saturation on a MEMS deformable mirror for woofer-tweeter adaptive optics

Katie Morzinski, Bruce Macintosh, Donald Gavel, and Daren Dillon
Opt. Express 17(7) 5829-5844 (2009)

Demonstrating sub-nm closed loop MEMS flattening

Julia W. Evans, Bruce Macintosh, Lisa Poyneer, Katie Morzinski, Scott Severson, Daren Dillon, Donald Gavel, and Layra Reza
Opt. Express 14(12) 5558-5570 (2006)

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Figures (19)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved