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Optics Letters

Optics Letters


  • Vol. 25, Iss. 4 — Feb. 15, 2000
  • pp: 221–223

Synthetic-aperture radar autofocus by maximizing sharpness

J. R. Fienup  »View Author Affiliations

Optics Letters, Vol. 25, Issue 4, pp. 221-223 (2000)

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To focus a synthetic-aperture radar image that is suffering from phase errors, a phase-error estimate is found that, when it is applied, maximizes the sharpness of the image. Closed-form expressions are derived for the gradients of a sharpness metric with respect to phase-error parameters, including both a point-by-point (nonparametric) phase function and coefficients of a polynomial expansion. Use of these expressions allows for a highly efficient gradient-search algorithm for high-order phase errors. The effectiveness of the algorithm is demonstrated with an example.

© 2000 Optical Society of America

OCIS Codes
(100.3010) Image processing : Image reconstruction techniques
(100.3020) Image processing : Image reconstruction-restoration
(100.5070) Image processing : Phase retrieval
(110.3000) Imaging systems : Image quality assessment
(110.5100) Imaging systems : Phased-array imaging systems
(280.6730) Remote sensing and sensors : Synthetic aperture radar

J. R. Fienup, "Synthetic-aperture radar autofocus by maximizing sharpness," Opt. Lett. 25, 221-223 (2000)

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