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Paraxial Curvature WFS algorithms. Assuming a paraxial beam propagating along the z-axis, we have the transport of intensity equation (TIE) :. Iterative FFT: C . Roddier and F. Roddier , J Opt Soc Am A 10, 2277-87 (1993) Series expansion: - PowerPoint PPT Presentation
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AOS Review • Tucson, Arizona • Sep 10, 2013 1
Paraxial Curvature WFS algorithms
Curvature WFS
Assuming a paraxial beam propagating along the z-axis, we have the transport of intensity equation (TIE):
Iterative FFT: C. Roddier and F. Roddier, J Opt Soc Am A 10, 2277-87 (1993)
Series expansion: T. E. Gureyev and K. A. Nugent, J. Opt. Soc. Am. A 13, 1670-1682 (1996)
Wavefront compensation:
Both the Iterative FFT and the Series Expansion algorithms are first order approximations valid only highly defocused images.
The accuracy of the WCS algorithm can be improved by iteratively compensating the effect of the estimated aberrations on the defocused images. (C. Roddier and F. Roddier, J Opt Soc Am A 10, 2277-87 (1993) )
AOS Review • Tucson, Arizona • Sep 10, 2013 2
Algorithmic Challenges for LSST
Curvature WFS
• LSST WFS challenges & algorithmic modifications
• Large Central Obscuration (61%)
• Fast f/number (f/1.23)
• Off-axis Distortion and Vignetting (~1.7o)
• Split Sensor Design (covering 1.51° to 1.84°)
AOS Review • Tucson, Arizona • Sep 10, 2013 3
Tests using PhoSim Images
Curvature WFS
telescope perturbations and atmospheric turbulence turned off
PhosimV3.2.6April 2013
Field=(1.185,1.185) Field=(1.237,1.237)
AOS Review • Tucson, Arizona • Sep 10, 2013 4
Tests of WFS with Perturbed LSST Model
Curvature WFS
AOS Review • Tucson, Arizona • Sep 10, 2013 5
Algorithmic Linearity
Curvature WFS
Z7 on M1M3 (in wave) Z7 on M1M3 (in wave)
AOS Review • Tucson, Arizona • Sep 10, 2013 6
Algorithmic Noise
Curvature WFS
(Algorithmic + atmospheric)Covariancematrix
(Algorithmic + atmospheric)Correlationcoefficients
Variance
Singular values