Results 141 to 150 of about 1,516 (173)
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Fresnel zone plates for two wavelengths
SPIE Proceedings, 1995This paper proposes two systems of Fresnel Zone Plates which could focus two parallel monochromatic and coherent beams (with different wavelengths), eliminating the wellknown chromatical aberrations of the classical construction.
Eugene O. Curatu +2 more
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Properties and Fabrication of Micro Fresnel Zone Plates
Applied Optics, 1973Arrays of ~2-mm diam, f/9, diffraction-limited Fresnel zone plates are made and measured. Amplitude zone plates are fabricated by conventional photolithographic techniques, while a specially developed evaporation/etching technique is used for phase zone plates.
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Aberrations of curved zone plates and Fresnel lenses
Applied Optics, 1977The generalization of zone plates and Fresnel lenses from the usual flat surfaces to curved surfaces is discussed. It is shown that, although Abbe's sine law applies to zone plates but not to Fresnel lenses, both can yield single-element aplanats if formed on a curved surface. Third-order aberration formulas are given.
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Fresnel Zone-Plate Diffraction Patterns
Journal of the Optical Society of America, 1969The diffraction patterns of the central aperture and the first 10 rings of the classical Fresnel zone plate are calculated in the principal focal plane for off-axis distances as large as the radius of the 10th ring. The zone-plate pattern is found by summation; near the axis it is compared with closed-form approximations.
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Fresnel zone plate: Anomalous foci
American Journal of Physics, 1976It is found that, when a zone plate is examined in practice, foci exist where there should be none. An approach is developed which reveals that the zone plate is a circular diffraction grating, which in turn explains how a hologram works in a very direct manner.
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[Thyroid scintigraphy with Fresnel zone plates].
Nuklearmedizin. Nuclear medicine, 1985Coded apertures supply a decoupling of resolution and sensitivity in scintigraphic imaging. The reconstructed images are focussed on different planes. The approach presented replaces the conventional collimator by three Fresnel zone plates in order to simulate a complex projection.
J, Meinke +2 more
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Sector-based Fresnel zone plate with extended depth of focus
Optics and Laser Technology, 2022JOSÉ A Gómez-Pedrero +2 more
exaly
Focusing specification of cross-like Fresnel zone plate
Optik, 2015Arash Sabatyan, Jila Rafighdoost
exaly