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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18 Nov 2008
TL;DR: In this article, the phase incursion variations dependencies on plane reflector diameter for the retransmitting range meter operating in the Fresnel zone were calculated using numerical technique, it has been determined that for the near reactive zone approach the reflector size variation causes fast increase of signal delay, within some places the sign of increasing changes.
Abstract: It has been calculated using numerical technique the phase incursion variations dependencies on plane reflector diameter for the retransmitting range meter operating in Fresnel zone. It has been determined that for the near reactive zone approach the reflector diameter variation causes fast increase of signal delay, within some places the sign of increasing changes. In the region of the Fresnel and Fraunhoffer zones boundary the dependencies become steady and speed of changing decreases with reflector moving away from the meter.
01 Jan 2011
TL;DR: In this paper, the authors review two methods of generating digital Fresnel holograms of three-dimensional microscopic specimens illuminated by incoherent light. But holography is not widely applied to the regime of fluorescence microscopy, because fluorescent light is incoherent and creating holograms requires a coherent interferometer system.
Abstract: Holography is an attractive imaging technique as it offers the ability to view a complete three-dimensional volume from one image. However, holography is not widely applied to the regime of fluorescence microscopy, because fluorescent light is incoherent and creating holograms requires a coherent interferometer system. We review two methods of generating digital Fresnel holograms of three-dimensional microscopic specimens illuminated by incoherent light. In the first method, a scanning hologram is generated by a unique scanning system in which Fresnel zone plates (FZP) are created by a coherently illuminated interferometer. In each scanning period, the system produces an on-axis Fresnel hologram. The twin image problem is solved by a linear combination of at least three holograms taken with three FZPs with different phase values. The second hologram reviewed here is the Fresnel incoherent correlation hologram. In this motionless holographic technique, light is reflected from the 3-D specimen, propagates through a spatial light modulator (SLM), and is recorded by a digital camera. Three holograms are recorded sequentially, each for a different phase factor of the SLM function. The three holograms are superposed in the computer, such that the result is a complex-valued Fresnel hologram that does not contain a twin image. When these two types of hologram are reconstructed in the computer, the 3-D properties of the specimen are revealed.
Patent•
18 Jan 2006
TL;DR: In this paper, a signal transmission system for predicting whether or not a primary Fresnel zone is brought into contact with an altitude cross-section a predetermined time after a transmitting device moves, and for displaying a caution when it is predicted that the primary Frescnel zones is coming into contact.
Abstract: PROBLEM TO BE SOLVED: To provide a signal transmission system for predicting whether or not a primary Fresnel zone is brought into contact with an altitude cross-section a predetermined time after a transmitting device moves, and for displaying a caution when it is predicted that the primary Fresnel zone is brought into contact. SOLUTION: An altitude cross-section between two points, that is, the position of a transmitting device and the position of a rotary antenna and the direct wave and primary Fresnel zone of a signal to be transmitted from the transmitting device between the two points are displayed, and whether or not the primary Frescnel zone is brought into contact with the altitude cross-section a prescribed time after the transmitting device moves is predicted, and when it is predicted that the primary Frescnel is brought into contact, a risk showing caution is displayed. COPYRIGHT: (C)2006,JPO&NCIPI
01 Jan 2000
TL;DR: In this article, a fiber optic surface sensor is described in which depolarization of light by a rough surface is measured, and an optimization of the measurement configuration aimed in restriction of the observation to the first Fresnel zone has been performed.
Abstract: A fiber optic surface sensor is described in which depolarization of light by a rough surface is measured. Polarization maintaining single mode fibers are used for the illumination and observation of the reflected light. An optimization of the measurement configuration aimed in restriction of the observation to the first Fresnel zone has been performed.
27 Sep 2022
TL;DR: In this article , a focusing dielectric lens based on the concept of a Fresnel step lens is introduced, which shows a smaller focus than the reference focus antenna while reducing the size by up to 53 % and the weight of the lens by nearly 48 %.
Abstract: In this paper, we present the design of a focusing dielectric lens, which is based on the concept of a Fresnel step lens. The concept and design of the lens is introduced. Different lenses are surveyed and compared using simulations and measurements with a frequency-modulated continuous-wave (FMCW) radar. The new design shows a smaller focus than the reference focus lens antenna while reducing the size by up to 53 % and the weight of the lens by nearly 48 %. In addition, the Fresnel-based lenses show a frequency dependency, which can be utilized to adjust the focal length.