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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.


Papers
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Patent
15 Jun 1979
TL;DR: In this article, the authors proposed to form the spot of all directions on the disc efficiently and to enable to increase the range of automatic focus drawing, by increasing the numerical aperture of coupling lens and locating the prism at the post stage of the coupling lens.
Abstract: PURPOSE:To form the spot of all directions on the disc efficiently and to enable to increase the range of automatic focus drawing, by increasing the numerical aperture of coupling lens and locating the prism at the post stage of the coupling lens. CONSTITUTION:To the semiconductor laser element 1 having non-isotropic spread angle, the coupling lens has greate automatic focussing drawing range to greater numberical aperture allowing to realize perfect automatic focussing to the up and down movement of the disc 4. Then, by using the coupling lens 2 having greater numerical aperture and inserting the prism 7 immediately after the coupling lens 2, the conversion of isotropic beam can be made. This light beam can obtain the isotropic spot 5 on the disc 4 by means of the objective lens 3, and since the numerical aperture of the coupling lens 2 is taken greater, the feedback of reflection light to the semiconductor laser 1 is greater, allowing to extend the range of automatic focus drawing.

5 citations

Patent
10 Oct 2012
TL;DR: An imaging lens as mentioned in this paper consists of a first lens having a positive power and convex surfaces on both sides; an aperture diaphragm; a second lens being a meniscus lens with a negative power and a convex surface on the object side; a third lens being an inverted cone lens with concave surfaces on the image surface.
Abstract: An imaging lens includes, arranged in sequence from the object side to the imaging surface side, a first lens having a positive power and convex surfaces on both sides; an aperture diaphragm; a second lens being a meniscus lens having a negative power and a convex surface on the object side; a third lens being a meniscus lens having a positive power and a concave surface on the object side; and a fourth lens having a negative power and concave surfaces on both sides. With this structure, the imaging lens is well corrected for various aberrations in spite of being compact in the lens radial direction and thin in the optical axis direction.

5 citations

Patent
18 Jul 1996
TL;DR: In this article, a high effective numerical aperture (NA) is achieved in an apparatus in which a real, 3D image is formed of an object placed in an aperture at the apex of one of two facing, axially-aligned concave mirrors.
Abstract: A microscope having a high effective numerical aperture (NA) is achieved in an apparatus in which a real, three-dimensional image is formed of an object placed in an aperture at the apex of one of two facing, axially-aligned concave mirrors. The three-dimensional image is acquired by a video camera positioned in a counterpart aperture at the apex of the other mirror and the acquired image is processed by computer. The processing corrects the acquired image using the point spread function of the mirror system which was previously obtained by positioning a point source of light throughout the object space and measuring the pixel values recorded by the camera's array of sensing element while the camera was positioned at different axial distances in the image space. When the diameter of the mirrors is large compared to the specimen object, substantially all of the light leaving the specimen is captured by the mirrors and focused upon the camera, thereby achieving a high effective numerical aperture for the system which affords excellent resolution, especially when examining transparent specimens.

5 citations

Journal ArticleDOI
TL;DR: In this article, an analysis of the far field pattern of a focal plane array in the case of two different lenses, a coma-free lens and a hyperbolic lens, and their comparison, are presented.
Abstract: In this paper an analysis of the far-field pattern of a focal-plane array in the case of two different lenses, a coma-free lens and a hyperbolic lens, and their comparison, are presented. Ray tracing and aperture integration are used. The calculated field pattern at W band is presented. The focal-plane elements are assumed to be corrugated horn. The f / D of the lens is 1.3. The coma-free lens is designed by step integration. The calculation results show that the coma-free lens is superior to the hyperbolic lens in the imaging performance. The coma-free lens can contain more pixels under the condition that the beam size and beam quality are almost constant over the range of angles scanned and the differences among beams gain less 1.8 dB. The aperture efficiency and directivity are also presented.

5 citations

Patent
25 Apr 1977
TL;DR: In this paper, a large-aperture ultra-wide angle photographic lens system which is compatible with filters designed for use with other lens systems and wherein various aberrations are favorably corrected is presented.
Abstract: A large-aperture ultra-wide angle photographic lens system which have such a small lens diameter as to be compatible with filters designed for use with other lens systems and wherein various aberrations are favorably corrected.

5 citations


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