Topic
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 Dec 1976
TL;DR: In this paper, a mechanism for a zoom lens of the type in which the aperture defining diaphragm mechanism moves axially of the lens and changes the position of the exit pupil was proposed.
Abstract: A mechanism for a zoom lens of the type in which the aperture defining diaphragm mechanism moves axially of the lens and changes the position of the exit pupil, where the mechanism modifies the aperture with changing focal length to maintain constant relative aperture at full relative aperture and further predetermines the stop down of the diaphragm mechanism as a function of selected relative aperture and focal length.
18 citations
TL;DR: In this article, the problem of coherent spherical wave passing through a circular aperture and subsequently focused by a lens was treated and an expression for the axial intensity beyond the lens was derived.
Abstract: We treat the problem of a coherent spherical wave passing through a circular aperture and subsequently focused by a lens. Using the Huygens–Fresnel integral representation, an expression is derived for the axial intensity beyond the lens. It predicts that the large-F-number focal shift may be reversed or eliminated, depending on the aperture–lens separation.
18 citations
Patent•
22 Jan 1970TL;DR: In this article, a single lens reflex camera having interchangeable lenses and an apparatus for determining the amount of exposure by measuring the light passing through the fully opened aperture of the lens is presented.
Abstract: A single lens reflex camera having interchangeable lenses and an apparatus for determining the amount of exposure by measuring the light passing through the fully opened aperture of the lens, in which a diaphragm aperture is preset by setting a preset diaphragm aperture setting ring, having a graduated aperture scale of equal spacing, and the starting point of the movement stroke of the ring is set at a fixed position irrespective of the extent of the maximum aperture of an interchangeable lens, and thus the scale for the maximum aperture of the lens comes to the fixed position, which is characterized by an integral coupling member provided on the above-mentioned preset aperture setting ring or to a preset cam engaged with the ring, and at the same time a correction projection, having such a different length as to correct the apparatus referring to the maximum aperture of the interchangeable lens, is provided at the lens so that when the lens is mounted on a camera, the projection makes such correction as compensating for a drop in value in the light measurement with a full-open aperture by a large aperture lens.
18 citations
18 citations
TL;DR: In this article, a tomographic imaging technique combined with coherence inversion is proposed for constructing a near-surface model from refraction events, which serves as a good background model for the tomographic reconstruction.
Abstract: A tomographic imaging technique combined with coherence inversion is proposed for constructing a near-surface model from refraction events. A model obtained from coherence inversion serves as a good background model for the tomographic reconstruction. A simultaneous iterative reconstruction technique (SIRT) algorithm was used for this purpose. This is a simple algorithm and can be easily adapted to irregular acquisition geometry and limited angular aperture. Using synthetic data it was shown that the proposed procedure can be used for determination of local velocity anomalies in a shallow subsurface. The technique was also tested on a real data set.
18 citations