Topic
Angular aperture
About: Angular aperture is a research topic. Over the lifetime, 1771 publications have been published within this topic receiving 27257 citations.
Papers published on a yearly basis
Papers
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25 Jun 1999TL;DR: In this paper, an infrared lens and detector system and associated method are disclosed that utilize infrared lenses to form an internal entrance pupil at which an internal aperture stop is placed to control the intensity of infrared radiation focused on the infrared detector.
Abstract: An infrared lens and detector system and associated method are disclosed that utilize infrared lenses to form an internal entrance pupil at which an internal aperture stop is placed to control the intensity of infrared radiation focused on the infrared detector. In more detailed respects, the infrared lens is an assembly including a first infrared lens, a second infrared lens spaced from the first lens to form a pupil between the first and second lenses, and an aperture stop disposed proximal the pupil. The aperture stop may have a fixed diameter or may have an aperture stop that is manually or automatically adjustable depending upon the intensity of the infrared radiation being viewed. Significantly, this lens assembly may be sealed for improved performance particularly in extreme conditions. In more detailed respects, the lens assembly forms a wide-angle lens and includes a diffractive surface on the second lens to reduce color aberrations and improve performance. In another respect, the infrared lens is part of a detector system that also includes an infrared detector, a signal processor, and a display.
19 citations
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08 Mar 1996TL;DR: In this paper, a magneto-optical disc system with a light-transmitting cover and an objective lens was described, which was used for bundling or focusing a laser beam on a magnetic recording layer.
Abstract: Disclosed is a magneto-optical disc system comprising a magneto-optical disc 40 with a light-transmitting cover 41, an objective lens 2 for bundling or focusing a laser beam on a magnetic recording layer 43 of the magneto-optical disc 40 in order to perform recording and/or reproduction, and a magnetic field generating unit 9 obtained by forming a coil pattern 7 in an optical glass 8. In the above system, the thickness t2 of the light-transmitting cover 41 is set to fall within the range of 0.6 to 0.1 mm, and the numerical aperture (NA) of the objective lens 2 is set to fall within the range of 0.55 to 0.70, so as to obtain high-density recording and/or reproduction.
19 citations
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31 Jul 1974TL;DR: In this paper, a two-element lens which provides an emerging beam of a height H from the optical axis where H is proportional to the product of the focal length of the lens and an angle made by an incident beam emanating from the focal point of the Lenses on the Optical axis thereof is defined.
Abstract: A two-element lens which provides an emerging beam of a height H from the optical axis where H is proportional to the product of the focal length of the lens and an angle made by an incident beam emanating from the focal point of the lens on the optical axis thereof.
19 citations
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19 citations
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TL;DR: In this paper, the focal shift and focal switch of Bessel-Gaussian (B-G) beams passing through a lens system with or without aperture was studied in detail.
Abstract: The focal shift and focal switch of Bessel–Gaussian (B–G) beams passing through a lens system with or without aperture is studied in detail. For the unapertured case, the necessary condition for the focal switch and the expression for the amplitude of the focal switch are derived. It is shown that if the truncation parameter δ ⩽ δ c or beam parameter β ⩽ β c (δc, βc are the corresponding critical values), there exits only one axial intensity maximum, and the focusing without focal shift can be achieved for u / f = 1 (u is the separation between the aperture and lens, f is the focal length of the lens); if δ > δ c and β > β c , there exist two axial intensity maxima, and the focal switch can take place at the turning point u / f = 1 for both apertured and unapertured cases. The dependence of the amplitude of focal switch and normalized axial intensity minimum on the truncation parameter, beam parameter and Fresnel number is also studied.
19 citations