Topic
Fresnel zone
About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.
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TL;DR: Stroboscopic X-ray topography at the synchrotron beam line was used to visualize the propagation of a 580 MHz surface acoustic waves (SAW) in LiNbO3 crystals and revealed an exceptional contrast of the concentric rings about the dislocation line, which is caused by coherent interaction of the secondary elastic waves.
11 citations
TL;DR: In this paper, the authors formulated the scintillation index at the receiver origin for a partially coherent off-axis Gaussian beam in atmospheric turbulence by employing the extended Huygens-Fresnel principle.
Abstract: The scintillation index at the receiver origin is formulated for a partially coherent off-axis Gaussian beam in atmospheric turbulence by employing the extended Huygens–Fresnel principle. Our formula correctly reduces to the existing coherent and partially coherent Gaussian beam scintillation indices in the limiting cases. For off-axis Gaussian beams with imaginary, real and complex displacement parameters, the scintillation index reduces when the incidence becomes more incoherent. When the source size of the off-axis Gaussian beam increases, the scintillations increase for partially coherent sources and decrease for incoherent sources, the tendency being observed for imaginary, real and complex displacement parameters. For the fully coherent off-axis Gaussian beams, increase in the source size first causes an increase in the scintillations, eventually reaching saturation at large source sizes, the increase is not monotonic and may exhibit a peak around the Fresnel zone sized off-axis Gaussian sources. Fo...
11 citations
TL;DR: Experimental results of focusing and imaging by a lens array and an elliptical zone plate are given and two methods of fabricating holographic zone plates for an IR or UV wavelength are proposed.
Abstract: Holographic microlens arrays and elliptical zone plates are fabricated on holographic plates and photoresists by interference between the first- and second-order diffracted waves from an ion etched Fresnel zone plate, which is made by electron-beam scanning and deep UV lithography. This method of fabrication is simple, and a holographic lens with a large numerical aperture and short focal length is obtained. Experimental results of focusing and imaging by a lens array and an elliptical zone plate are given. Two methods of fabricating holographic zone plates for an IR or UV wavelength are also proposed.
11 citations
02 Jun 2009
TL;DR: In this paper, the authors implemented in plane launching and focusing surface plasmons by fabricating Fresnel zone-plate like grating on a thin gold film and observed a subwavelength focal spot at 830nm vacuum wavelength.
Abstract: We implement in plane launching and focusing surface plasmons by fabricating Fresnel zone-plate like grating on a thin gold film. A subwavelength focal spot, with transverse FWHM=712nm, is observed at 830nm vacuum wavelength.
11 citations
TL;DR: A soft x-ray microscope using Fresnel zone plates as optical imaging elements was installed at the Photon Factory as mentioned in this paper, which makes use of undulator radiation as a source of soft x rays ranging from 2.0 to 3.0 nm in wavelength.
Abstract: A soft x‐ray microscope using Fresnel zone plates as optical imaging elements was installed at the Photon Factory. It makes use of undulator radiation as a source of soft x rays ranging from 2.0 to 3.0 nm in wavelength. The optical system was designed to match to the undulator radiation. A performance test was made at 2.66 nm by various pitches of transmission gratings. Those magnified images were taken with a magnification of 230 and exposure times of about 10 s. The modulation transfer function was measured over the spatial frequency up to 3300 lp/mm. Further, magnified images of some biological specimens were obtained.
11 citations