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Proceedings Paper

All-optical image sharpness sensor for propagation and imaging
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Paper Abstract

Undesirable turbulence effects present during propagation and imaging through the atmosphere are often reduced using adaptive optics. Many current adaptive optics systems use the Shack-Hartmann wavefront sensor requiring measurement and reconstruction of the incoming wavefront at the pupil plane. Indirect wavefront sensing methods, such as image sharpening, are based on data obtained from the image plane. We are developing an image sharpness sensor based on the Fourier spectrum of an image. High spatial frequencies contain information about the edges and fine detail of the image. Our premise is the maximizing of the high spatial frequencies will sharpen the image. In our setup the Fourier transform of the image is generated optically (and essentially instantaneously) and then various spatial-frequency bands are filtered with an opaque mask. The remaining Fourier spectrum is integrated optically and a sharpness signal is measured with a single photodetector. The collected sharpness value is used in a closed-loop to control the deformable mirror until the sharpness is maximized. We have constructed both a simulation and a laboratory experiment to study the sensor and its performance in an adaptive optics system.

Paper Details

Date Published: 15 February 2008
PDF: 6 pages
Proc. SPIE 6878, Atmospheric Propagation of Electromagnetic Waves II, 68780E (15 February 2008); doi: 10.1117/12.768172
Show Author Affiliations
Kristin N. Walker, Univ. of North Carolina at Charlotte (United States)
Robert K. Tyson, Univ. of North Carolina at Charlotte (United States)


Published in SPIE Proceedings Vol. 6878:
Atmospheric Propagation of Electromagnetic Waves II
Olga Korotkova, Editor(s)

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