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Wavefront Sensing for WFIRST with a Linear Optical ModelIn this paper we develop methods to use a linear optical model to capture the field dependence of wavefront aberrations in a nonlinear optimization-based phase retrieval algorithm for image-based wavefront sensing. The linear optical model is generated from a ray trace model of the system and allows the system state to be described in terms of mechanical alignment parameters rather than wavefront coefficients. This approach allows joint optimization over images taken at different field points and does not require separate convergence of phase retrieval at individual field points. Because the algorithm exploits field diversity, multiple defocused images per field point are not required for robustness. Furthermore, because it is possible to simultaneously fit images of many stars over the field, it is not necessary to use a fixed defocus to achieve adequate signal-to-noise ratio despite having images with high dynamic range. This allows high performance wavefront sensing using in-focus science data. We applied this technique in a simulation model based on the Wide Field Infrared Survey Telescope (WFIRST) Intermediate Design Reference Mission (IDRM) imager using a linear optical model with 25 field points. We demonstrate sub-thousandth-wave wavefront sensing accuracy in the presence of noise and moderate undersampling for both monochromatic and polychromatic images using 25 high-SNR target stars. Using these high-quality wavefront sensing results, we are able to generate upsampled point-spread functions (PSFs) and use them to determine PSF ellipticity to high accuracy in order to reduce the systematic impact of aberrations on the accuracy of galactic ellipticity determination for weak-lensing science.
Document ID
20120014609
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Jurling, Alden S. (Rochester Univ. NY, United States)
Content, David A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 26, 2013
Publication Date
July 1, 2012
Subject Category
Optics
Report/Patent Number
GSFC.CP.6938.2012
Meeting Information
Meeting: SPIE Astronomical Telescopes and Instrumentation
Location: Amsterdam
Country: Netherlands
Start Date: July 1, 2012
End Date: July 6, 2012
Sponsors: International Society for Optical Engineering
Distribution Limits
Public
Copyright
Public Use Permitted.

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