Reduced Tolerance Imaging I
Technical rept. 15 Oct 1984-14 Oct 1985
ENVIRONMENTAL RESEARCH INST OF MICHIGAN ANN ARBOR
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The reduced tolerance imaging concept is to use imaging system hardware of reduced complexity to make phase-error-degraded measurements or to lose phase information altogether and then reconstruct diffraction-limited imagery in a post-detection processing stage using a phase retrieval algorithm. In the first year of a two-year effort several advances were made toward this end. An estimation theoretic Cramer-Rao lower bound on the error of estimating a coherent image for far-field Fourier intensity squared modulus measurements was derived for the case of Gaussian detector noise. Uniqueness of reconstruction from Fourier modulus assuming a priori known support was proven for a particular class of objects -- sampled objects whose support the area outside of which it is zero has a convey hull with no parallel sides. A closed- form recursive reconstruction algorithm was developed for reconstructing such objects via their autocorrelation functions. Simulations showed the closed-form solution to be sensitive to noise compared with iterative Fourier transform algorithms.
- Atmospheric Physics
- Radiofrequency Wave Propagation