Biomedical subjects

G W Carhart

Publications and source records attributed to G W Carhart.

2 recordsLinked to original sources

PubMed2001

Adaptive optics with advanced phase-contrast techniques. II. High-resolution wave-front control.

A wave-front control paradigm based on gradient-flow optimization is analyzed. In adaptive systems with gradient-flow dynamics, the output of the wave-front sensor is used to directly control high-resolution wavefront correctors without the need for wave-front phase reconstruction (direct-control systems). Here, adaptive direct-control systems with advanced phase-contrast wave-front sensors are analyzed theoretically, through numerical simulations, and experimentally. Adaptive system performance is studied for atmospheric-turbulence-induced phase distortions in the presence of input field intensity scintillations. The results demonstrate the effectiveness of this approach for high-resolution adaptive optics.

Journal Article↗

PubMed2001

Anisoplanatic imaging through turbulent media: image recovery by local information fusion from a set of short-exposure images.

A wide-field-of-view white-light imaging experiment with artificially generated turbulence layers located between the extended object and the imaging system is described. Relocation of the turbulence sources along the imaging path allowed the creation of controllable anisoplanatic effects. We demonstrate that the recently proposed synthetic imaging technique [J. Opt. Soc. Am. A 16, 1623 (1999)] may result in substantial improvement in image quality for highly anisoplanatic conditions. It is shown that for multisource objects located at different distances the processing of turbulence-degraded short-exposure images may lead to a synthetic image that has an image quality superior to that of the undistorted image obtained in the absence of turbulence (turbulence-induced image quality enhancement).

Journal Article↗