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: In this article, the authors use diffraction theory to explain the reflector edge effect on amplitude and the amplitude variation within the Fresnel zone, and demonstrate that AVO analysis can be incorrect.
Abstract: Reflection energy from a linear reflector comes from an integrant over an aperture often described by the Fresnel zone. Within the Fresnel zone, the diffraction energy constructively builds the reflection energy. This paper uses diffraction theory to explain the reflector edge effect on amplitude and the amplitude variation within the Fresnel zone. Thus, discuss the Fresnel zone effect for AVO analysis on stack data. When the target is smaller than the Fresnel zone size or the reflection point is close to the reflector edge than the Fresnel radius, the amplitude is the result of diffraction effect on reflection. It also illustrates that AVO analysis within the Fresnel zone can be incorrect. Migration can improve it.
3 citations
Patent•
05 Apr 1995
TL;DR: In this paper, a reflecting surface aerial using the phase correcting plane of one dimensional Fresnel zone, the phase correction amount is one-fourth of the wave length, which has the advantages of high efficiency and good off-axis scanning feature.
Abstract: The present invention discloses a reflecting surface aerial. The aerial uses the phase correcting plane of one dimensional Fresnel zone, the phase correcting amount is one-fourth of the wave length. The invention has the advantages of high efficiency and good off-axis scanning feature.
3 citations
3 citations
TL;DR: In this paper, the photon sieve is used as an inexpensive null-corrector for testing a parabolic primary, which can enlarge the holes significantly beyond the width of a Fresnel zone such that more light is transmitted and greater efficiency is achieved.
Abstract: We present the concept of using a photon sieve as an inexpensive null-corrector. A photon sieve is a diffractive element consisting of a large number of holes precisely positioned according to an underlying Fresnel Zone Plate geometry. Using diffraction theory we can enlarge the holes significantly beyond the width of a Fresnel zone such that more light is transmitted and greater efficiency is achieved. Added to this, modification of the equations used to generate the hole locations can also permit the construction of any desired wavefront instead of a simple infinite-conjugate ratio focusing optic. This makes it an ideal optic for testing larger components in a null-corrector configuration. In this talk we will present theoretical and experimental results from tests of this idea. These include the fabrication of a 0.1m diameter intensity photon sieve null-corrector specifically for testing a parabolic primary.
3 citations
TL;DR: In this paper, the amplitude and phase of diffracted ultrasonic waves have been measured, and a graphical treatment of the results is performed by simply drawing vectors (phasors) in the complex plane.
Abstract: The diffraction of ultrasound by a circular disk and an aperture of the same size have been investigated as a demonstration of Babinet's principle in the Fresnel regime. The amplitude and the phase of diffracted ultrasonic waves have been measured, and a graphical treatment of the results is performed by simply drawing vectors (phasors) in the complex plane. The results verify Babinet's principle. It is also found that the incident wave is indeed 90 deg behind the phase of the wave passing through on the central axis of a circular aperture. This paradox has previously been regarded as a defect of Fresnel's theory. The apparatus used is intended as a table-top instrument for the student laboratory in general science and engineering classes.
3 citations