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Proceedings Paper

Design of mobile phone lens with extended depth of field based on point-spread function focus invariance
Author(s): Hsin-Yueh Sung; Sidney S. Yang; Horng Chang
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Paper Abstract

Due to the application of mobile phone lens, the clear image for the different object distance from infinity to close-up creates a new bargaining. We found that wave-front coding applied to extend the depth of field may solve this problem. By means of using cubic phase mask (CPM), the blurred point-spread function (PSF) is substantially invariant to defocus. Thus, the ideal hyperfocal distance condition can be satisfied as long as the constant blurred image can eventually be recovered by a simple digital signal processing. In this paper, we propose a different design method of computational imaging lens for mobile phone up to ideal depth of field based on PSF focus invariance. Because of the difficulty for comparing the similarity to different PSFs, we define a new metric, of correlation, to evaluate and optimize the PSF similarity. Besides, by means of adding the anti-symmetric free form phase plate at aperture stop and using the correlation and Strehl ratio as the two major optimization operands, we can get the optimum phase plate surface to achieve the required extended depth of field (EDoF). The resulted PSF on focal plane is significantly invariant to object distance varying from infinity to 10cm.

Paper Details

Date Published: 11 September 2008
PDF: 11 pages
Proc. SPIE 7061, Novel Optical Systems Design and Optimization XI, 706107 (11 September 2008); doi: 10.1117/12.794079
Show Author Affiliations
Hsin-Yueh Sung, National Tsing Hua Univ. (Taiwan)
Sidney S. Yang, National Tsing Hua Univ. (Taiwan)
Horng Chang, Industrial Technology Research Institute (Taiwan)

Published in SPIE Proceedings Vol. 7061:
Novel Optical Systems Design and Optimization XI
R. John Koshel; G. Groot Gregory; James D. Moore; David H. Krevor, Editor(s)

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