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Proceedings Paper

Variable phaseplates for focus invariant optical systems
Author(s): T. Hellmuth; A. Bich; R. Börret; A. Holschbach; A. Kelm
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Paper Abstract

Depth of focus can be enhanced with cubic phaseplates located at the exit pupil of an optical system without significant loss of resolution. The enhancement factor is proportional to the strength of the phaseplate. The digital image is inversely filtered. The stronger the phaseplate is the stronger the inverse filter function must be. This causes increasing noise for high spatial frequencies in the restored image. Therefore, an optimum strength of the cubic phaseplate has to be chosen for the respective situation. A variable phaseplate system has been realized and tested. The performance of the setup has been experimentally studied. Applications and practical aspects are discussed in particular regarding barcode readers.

Paper Details

Date Published: 14 October 2005
PDF: 11 pages
Proc. SPIE 5962, Optical Design and Engineering II, 596215 (14 October 2005); doi: 10.1117/12.622699
Show Author Affiliations
T. Hellmuth, Aalen Univ. of Applied Sciences (Germany)
A. Bich, Aalen Univ. of Applied Sciences (Germany)
R. Börret, Aalen Univ. of Applied Sciences (Germany)
A. Holschbach, Aalen Univ. of Applied Sciences (Germany)
A. Kelm, Aalen Univ. of Applied Sciences (Germany)


Published in SPIE Proceedings Vol. 5962:
Optical Design and Engineering II
Laurent Mazuray; Rolf Wartmann, Editor(s)

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