John H . Seldin

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We describe several results characterizing the Hubble Space Telescope from measured point spread functions by using phase-retrieval algorithms. The Cramer-Rao lower bounds show that point spread functions taken well out of focus result in smaller errors when aberrations are estimated and that, for those images, photon noise is not a limiting factor.(More)
Three-dimensional imaging provides profile information not available with conventional twodimensional imaging. Many three-dimensional objects of interest are opaque to the illuminating radiation, meaning that the object exhibits surface, as opposed to volume, scattering. We investigate the use of an opacity constraint to perform three-dimensional phase(More)
Space-variant blur is encountered when objects extend beyond the isoplanatic patch associated with the intervening atmospheric turbulence. The method of phase diversity, used to estimate jointly the object and the aberrations, is generalized to accommodate turbulence-induced space-variant blur. This generalization utilizes a parametric model for the blur(More)
Space-variant blur occurs when imaging through volume turbulence over sufficiently large fields of view. Space-variant effects are particularly severe in horizontal-path imaging, slant-path (air-to-ground or ground-to-air) geometries, and ground-based imaging of low-elevation satellites or astronomical objects. In these geometries, the isoplanatic angle can(More)
We are developing a technique to measure segment misalignment of large telescopes based on wavefront estimation using phase-diverse (inand out-of-focus) images. We report the current results of an experiment to measure piston errors on the Keck II primary segmented mirror, through atmospheric turbulence, using phase-diverse phase retrieval. The segment(More)
The collection, seeing compensation, and temporal filtering of two high-resolution time-sequences of solar photospheric images are described. 44 80 image sequences of co-spatial and co-temporal 430.5 nm G band and 436.4 nm continuum filtergrams, were obtained with the 47.5 cm Swedish Vacuum Solar Telescope. One data set covers 5 hours of photospheric(More)
93 PREFACE This report documents the results of the first phase of a proposed two-phase study called "Focal-Plane Alignment Sensing" performed by the Optical & Infrared Order 0028 within the Infrared Information Anialysis Center (IRIA) program, contract number DLA900-88-D-0392, for which the Defense Electronic Supply Center (DESC), Dayton, Ohio, serves as(More)
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