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Angular aperture

About: Angular aperture is a research topic. Over the lifetime, 1771 publications have been published within this topic receiving 27257 citations.


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Patent
15 Mar 1994
TL;DR: In this article, a confocal scanning imaging system utilizes only one aperture for both the incident light from the light source and return light from an object to improve its performance, the aperture plate is tilted with respect to the light path, the surfaces are coated with anti-reflection coating, the surface is optically flat and the size of the aperture is designed to act as a one-way spatial filter.
Abstract: A confocal scanning imaging system utilizes only one aperture for both the incident light from the light source and return light from the object To improve its performance, the aperture plate is tilted with respect to the incident light path, the surfaces are coated with anti-reflection coating, the surfaces are optically flat, and the size of the aperture is designed to act as a one-way spatial filter Other devices may be strategically placed to minimize the negative effects from scattered light

33 citations

Journal ArticleDOI
TL;DR: In this article, a design method for a dielectric lens antenna with a wide beam scanning angle necessary for collision avoidance radar and car-to-car communication in an ITS was presented.
Abstract: A design method is presented for a dielectric lens antenna with a wide beam scanning angle necessary for collision avoidance radar and car-to-car communication in an ITS. First, a design method for an antenna with a superior wide angle beam scanning capability is presented by providing an aperture distribution satisfying the Abbe sine condition for wide angle beam scanning in the shaped lens design to accomplish an arbitrary aperture distribution. Aperture distributions and positions of radiators in the case of wide angle beam scannings are obtained. Next, for evaluation of wide angle beam scanning, antenna performances are compared with the well-known bifocal antenna. In the case of a bifocal lens antenna, it is found that there exists a limit to the realizability of lens surfaces when the lens thickness is large because of the limited number of designed lens points. Radiation characteristics are compared in an antenna with an aperture diameter of 20 wavelengths. In the case of small F/D ratios that can reduce the antenna depth, the shaped lens provides better gains and sidelobe levels than a bifocal lens. When the beam is steered up to 30° in a lens with F/D = 0.5, it is shown that the gain deterioration is 5 dB and the sidelobe level increase is 5 dB. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 89(2): 1–12, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20185

33 citations

Journal ArticleDOI
TL;DR: In this article, the light distribution in the image of a sinusoidal and of a bar (crenelate or square-wave) pattern produced by diffraction at a "slit" aperture (straight-sided and infinitely long) and at a circular aperture was derived.
Abstract: Expressions are derived for the light distribution in the image of a sinusoidal and of a bar (crenelate or “square-wave”) pattern produced by diffraction at a “slit” aperture (straight-sided and infinitely long) and at a circular aperture. In every case, when the pattern has an infinite number of repetitions, the distribution is uniform for the spatial frequency that represents Rayleigh’s limit for two-line sources and a slit aperture; this is thus the absolute objective limit of resolution. In practice, radiation detectors have different thresholds, and, since the rate at which the contrast in the image diminishes as the frequency approaches the limit varies with the type of object pattern and the shape of the diffracting aperture, the measured value of resolving power also varies. A table of the line spread-function for a circular aperture is given.

33 citations

Patent
28 Mar 2007
TL;DR: In this article, the authors proposed an imaging lens constituted of four lenses, whose aberrations are satisfactorily corrected though it is smaller in size than the imaging lens of the conventional type.
Abstract: PROBLEM TO BE SOLVED: To provide an imaging lens constituted of four lenses, whose aberrations are satisfactorily corrected though it is smaller in size than the imaging lens of the conventional type. SOLUTION: The imaging lens for forming a subject image at the photoelectric conversion part of a solid imaging device comprises an aperture diaphragm, a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power and a fourth lens that is a biconcave lens with at least one aspherical surface and having negative refractive power in order from an object side, and satisfies following conditional expressions: 0.30

33 citations

Patent
02 Dec 1986
TL;DR: In this article, a dual lens (70, 80) type array antenna system with a small array feed network is described, which includes a bootlace-type microwave aperture lens (80) with an array of radiating elements (85) arranged along the linear aperture (82), a pickup element along the curved inner surface (81), and an intermediate optical corrective lens(70), a feed array (65) for illuminating the corrective lens with a source distribution, and with a power divider (55) and phase shifters (60) arranged to drive the feed array.
Abstract: An optical limited scan antenna system. The invention is a dual lens (70, 80) type array antenna system with a small array feed network (65). The system includes a bootlace-type microwave aperture lens (80) with an array of radiating elements (85) arranged along the linear aperture (82) and an array of pickup elements (75) arranged along the curved inner surface (81), an intermediate optical corrective lens (70), a feed array (65) for illuminating the corrective lens with a source distribution, and with a power divider (55) and phase shifters (60) arranged to drive the feed array. The corrective lens (70) is circularly symmetric (spherically symmetric in the three-dimensional case), and its radially varying dielectric constant is such that a point source on its surface is focused to an image point on the inner surface (81). The pickup elements (75) on the curved surface (81) of the aperture lens are coupled to corresponding radiating elements (85) on the linear aperture (82). The corrective (70) and aperture lenses (80) cooperate to map an input or source distribution into an aperture distribution which is a scaled version of the source distribution. The system results in high efficiency obtained with a minimum number of active elements and relatively low cost optical components.

33 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20234
20224
20217
20207
20195
201811