Search results for "Fresnel zone antenna"

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Spectral anomalies in focused waves of different Fresnel numbers

2004

Light propagation induces remarkable changes in the spectrum of focused diffracted beams. We show that spectral changes take place in the vicinity of phase singularities in the focal region of spatially coherent, polychromatic spherical waves of different Fresnel numbers. Instead of the Debye formulation, we use the Kirchhoff integral to evaluate the focal field accurately. We find that as a result of a decrease in the Fresnel number, some cylindrical spectral switches are geometrically transformed into conical spectral switches.

PhysicsDiffractionFresnel zoneGeometrical opticsbusiness.industryFresnel zone antennaAstrophysics::Instrumentation and Methods for AstrophysicsPhysics::OpticsFresnel integralAtomic and Molecular Physics and OpticsSpectral lineElectronic Optical and Magnetic MaterialsOpticsFresnel numberComputer Vision and Pattern RecognitionbusinessFresnel diffractionJournal of the Optical Society of America A
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Broadband space-variant Fresnel processor

2002

We present a radically new class of optical setup working with white-light illumination, namely, a chromatically compensated processor operating in the Fresnel domain. The optical configuration is a hybrid (diffractive-refractive) three-lens system that exhibits an intermediate achromatic Fresnel plane and an output image plane without chromatic distortion. As a first application of this optical arrangement we develop a parallel space-variant color pattern-recognition experiment with white light.

Physicsbusiness.industryPlane (geometry)Fresnel zone antennaPhysics::OpticsImage planeAtomic and Molecular Physics and Opticslaw.inventionOpticsAchromatic lenslawDistortionFresnel numberChromatic scalebusinessFresnel diffraction
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