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Proceedings Paper

Performance of extended depth of field systems and theoretical diffraction limit
Author(s): Nicolas Bachelard; Frédéric Guichard; Frédéric Cao; Imène Tarchouna
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Paper Abstract

Extended depth of field (EDOF) cameras have recently emerged as a low-cost alternative to autofocus lenses. Different methods, either based on longitudinal chromatic aberrations or wavefront coding have been proposed and have reached the market. The purpose of this article is to study the theoretical performance and limitation of wavefront coding approaches. The idea of these methods is to introduce a phase element making a trade-off between sharpness at the optimal focus position and the variation of the blur spot with respect to the object distance. We will show that there are theoretical bounds to this trade-off: knowing the aperture and the minimal MTF value for a suitable image quality, the pixel pitch imposes the maximal depth of field. We analyze the limitation of the extension of the depth of field for pixel pitch from 1.75μm to 1.1μm, particularly in regards to the increasing influence of diffraction.

Paper Details

Date Published: 24 January 2011
PDF: 11 pages
Proc. SPIE 7876, Digital Photography VII, 787607 (24 January 2011); doi: 10.1117/12.872459
Show Author Affiliations
Nicolas Bachelard, DxO Labs. (France)
Frédéric Guichard, DxO Labs. (France)
Frédéric Cao, DxO Labs. (France)
Imène Tarchouna, DxO Labs. (France)

Published in SPIE Proceedings Vol. 7876:
Digital Photography VII
Francisco H. Imai; Feng Xiao, Editor(s)

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