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Proceedings Paper

Simulation of focus invariant optical systems
Author(s): Thomas Hellmuth; Stefan Rathgeb
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Paper Abstract

Normally, depth of focus and resolution of an optical system are complementary parameters. According to an established technique known as wavefront coding the depth of focus can be enhanced by inserting a phaseplate with a cubic surface function into the exit pupil plane of an optical system. Although contrast is reduced the image quality can be restored very efficiently by inverse filtering because the modulation transfer function (MTF) almost does not change when the system is defocused. In addition the MTF has no zero crossings. Therefore inverse filtering has no singularities. Thus, three dimensional objects can be imaged with microscopes with a large depth of focus. The waveoptical performance of a commercial microscope equipped with a cubic phase plate has been simulated. The simulation results are discussed and compared with experimental data. The system has been analyzed both regarding effects specifically related to the phase plate design and regarding effects related to the optical properties which result from the combination of the phase plate with the microscope system. A variable phase plate design is also presented which can be adapted to specific objects and optical systems.

Paper Details

Date Published: 18 February 2004
PDF: 9 pages
Proc. SPIE 5249, Optical Design and Engineering, (18 February 2004); doi: 10.1117/12.513437
Show Author Affiliations
Thomas Hellmuth, Fachhochschule Aalen (Germany)
Stefan Rathgeb, Fachhochschule Aalen (Germany)

Published in SPIE Proceedings Vol. 5249:
Optical Design and Engineering
Laurent Mazuray; Philip J. Rogers; Rolf Wartmann, Editor(s)

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