Paper
4 January 2008 Multi-annular phase plate for extended depth-of-field imaging system
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Abstract
Extending the depth of field (DOF) of incoherent optical systems has been an active research topic for many years, and the extended depth of field (EDOF) system can be used in many fields. We developed a novel circular pure phase plate to extend the DOF by a factor of 4 without decrease of optical power in image plane. The plate is divided into several equal-area annular zones and placed in the exit pupil of a standard optical imaging system. The annular zones alternately eliminate the influence of different defocus beside the ideal Gauss object plane. The comparisons of the MTF and PSF curves between two systems show that the system employing the phase plate has a large DOF while preserving an acceptable resolution. Also, the images captured by the system don't have to be restored by a digital filter before next processing. And the simulation of imaging a spoke target in several defocused condition also confirms the EDOF of the imaging system. The DOF can be adjusted by two parameters of the phase plate: defocus compensation parameter and zone number. We gave the relation curves between system's performances and parameters of the plate.
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Xutao Mo, Wenyao Liu, and Jinjiang Wang "Multi-annular phase plate for extended depth-of-field imaging system", Proc. SPIE 6832, Holography and Diffractive Optics III, 68321L (4 January 2008); https://doi.org/10.1117/12.754785
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KEYWORDS
Imaging systems

Modulation transfer functions

Optical imaging

Point spread functions

Image quality standards

Digital filtering

Image restoration

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