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Session 13 - Image Processing, Chromosphere.
Oral session, Monday, June 30
Ballroom A, Chair: Thomas Metcalf

[13.02] Indirect Imaging in Solar Physics

G. J. Hurford (Caltech)

Conventional imaging systems are based on reflecting or refracting optics which focus incoming radiation on a multi- element focal plane detector. At radio and hard x-ray wavelengths, however, this is not possible and we must resort to indirect imaging. Such an approach typically reconstructs the best estimate of the source image from measurements of its Fourier components. Examples of such systems in a solar context are the VLA and Owens Valley Solar Array in the radio regime and the Yohkoh HXT and HESSI at x-ray wavelengths. The properties and limitations of indirect imaging techniques are especially relevant for instruments which combine indirect imaging and high- resolution spectroscopy.

In this paper, we review the factors which influence reconstructed image characteristics and quality, and discuss how instrumental and calibration errors affect the sensitivity, resolution and dynamic range of the resulting images. Reconstruction algorithms are also discussed with emphasis on their inherent assumptions on how the choice of technique can influence the image properties. Finally, techniques are reviewed for overcoming calibration and atmospheric effects.

Program listing for Monday