Angular aperture

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

Images of an Incoherent Triangular-Wave Pattern by a Slit Aperture in the Presence of Defocusing

Abstract: The effect of defocusing on the diffraction images of a general periodic triangular-wave object has been investigated for the case of a narrow rectangular aperture. Results in the form of curves have been given for irradiance distribution and contrast in the images. The aperture has been assumed to be illuminated incoherently. A close similarity has been shown between the sine-wave response and triangular-wave response of a particular object function.

Numerical Analysis of the Near-field Diffraction Pattern of a Small Aperture

Abstract: We show the three-dimensional (3-D) distribution of the time-averaged Poynting vector in the near-field of a small aperture (radius < λ) using Bethe's diffraction theory Our numerical calculation shows that the characteristic of the near-field diffraction depends on the incident angle of the beam on the aperture Specifically, the near-field diffraction corresponding to the normal incident has a quite different character than that of the oblique incident We also discuss the variation of the propagation of the time-averaged Poynting vector with the aperture size, the wavelength and the distance from the aperture

Image pickup lens and image pickup apparatus

Abstract: An image pickup lens includes, in order from an object side to an image side, an aperture stop, a first lens element having a positive refractive power, a second lens element having a negative refractive power and a biconcave shape, a third lens element having a positive refractive power and a meniscus shape whose concave surface faces the object side, and a fourth lens element having a negative refractive power. In the image pickup lens, the following conditional expressions are satisfied, 0.20< f/|f 2 |<0.9 ν d 1−ν d 2 >25 where f denotes the focal length of the entire lens system, f 2 denotes the focal length of the second lens element, νd 1 denotes the Abbe number of the first lens element, and νd 2 denotes the Abbe number of the second lens element.

Imaging lens system and imaging apparatus

Abstract: An imaging lens system includes three lens groups having four lenses including a first lens, a second lens, a third lens, and a fourth lens arranged in order from an object side, and an aperture stop arranged between the first lens and the second lens. The second lens and the third lens are joined each other. The first lens is a negative meniscus lens having a convex surface at an object side. The second lens is a positive lens having a convex surface having a large curvature at an image side. The third lens is a negative lens having a concave surface having a large curvature at an object side. The fourth lens is a positive lens having a convex surface having a large curvature at an image side. The following conditions are satisfied: 1.4<| f 1/ F |<2.2 0.4<| f 1/ f 23|<1.6 where F is a focal length of the entire imaging lens system, f1 is a focal length of the first lens, and f23 is a combined focal length of the second lens and the third lens which are joined each other. The following condition is satisfied: 1.80< N 1 where N1 is a refractive index of material of the first lens for a d line.