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A Novel Method of High Accuracy, Wavefront Phase and Amplitude Correction for CoronagraphyDetection of extra-solar, and especially terrestrial-like planets, using coronagraphy requires an extremely high level of wavefront correction. For example, the study of Woodruff et al. (2002) has shown that phase uniformity of order 10(exp -4)lambda(rms) must be achieved over the critical range of spatial frequencies to produce the approx. 10(exp 10) contrast needed for the Terrestrial Planet Finder (TPF) mission. Correction of wavefront phase errors to this level may be accomplished by using a very high precision deformable mirror (DM). However, not only phase but also amplitude uniformity of the same scale (10(exp -4)) and over the same spatial frequency range must be simultaneously obtained to remove all residual speckle in the image plane. We present a design for producing simultaneous wavefront phase and amplitude uniformity to high levels from an input wavefront of modest quality. The design uses a dual Michelson interferometer arrangement incorporating two DMs and a single, fixed mirror (all at pupils) and two beamsplitters: one with unequal (asymmetric) beam splitting and one with symmetric beam splitting. This design allows high precision correction of both phase and amplitude using DMs with relatively coarse steps, is substantially achromatic and permits a simple correction algorithm.
Document ID
20040021353
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Bowers, Charles W.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Woodgate, Bruce E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lyon, Richard G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Solar Physics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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