Angular aperture

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

Noncollinear acousto‐optic filter with large angular aperture

Abstract: A new type of noncollinear acousto‐optic filter with large angular aperture is described. By an appropriate choice of acoustic wave propagation direction, the momentum mismatch caused by the angular deviation of the incident light from the matching condition in a noncollinear interaction can be compensated by the angular change of optical birefringence. A TeO2 noncollinear acousto‐optic filter was constructed that had a half‐power bandwidth of 40 A at an f/4 (±7°) aperture. Tuning from 700 to 450 nm is obtained by changing the acoustic frequency from about 100 to 180 MHz. About 95% maximum transmission is obtained with an electrical power density of 1 W/cm2 applied to the transducer.

Imaging lens and imaging device

Abstract: [Problem] To enable a reduction in size, a reduction in costs, the widening of the angle of view and an increase in performance of an imaging lens, and also to eliminate restrictions on the imaging element used. [Solution] An imaging lens (1) is formed substantially from six lenses in the following order from the object side: a negative first lens (L1); a negative second lens (L2); a positive third lens (L3); a positive fourth lens (L4); a negative fifth lens (L5); and a positive sixth lens (L6). The surface on the object side of the second lens (L2) is a concave surface, and the surface on the object side of the third lens (L3) is a concave surface.

Dielectric lens, dielectric lens device, design method of dielectric lens, manufacturing method and transceiving equipment of dielectric lens

Abstract: A design process first determines a desired aperture distribution, then converts the electric power conservation law, Snell's law on the rear face side of a dielectric lens, and the formula representing light-path-length constraint, into simultaneous equations, and computes the shapes of the surface and rear face of the dielectric lens depending on the azimuthal angle θ of a primary ray from the focal point of the dielectric lens to the rear face of the dielectric lens, and then reduces the light path length in the formula showing light-path-length constraint by an integral multiple of the wavelength when the coordinates on the surface of the dielectric lens reach a predetermined restriction thickness position. A dielectric lens is designed by sequentially changing the lazimuthal angle θ from its initial value, and also repeating the second and third steps. Thus, downsizing and quantification is realized by zoning while keeping antenna properties at the time of constituting a dielectric lens antenna in a good condition.

Study of near-zone fields of a small aperture

Abstract: The structure or the near‐zone field transmitted through an electrically small aperture in a perfectly conducting plane is investigated. We dwell on two issues that are of importance to engineers analyzing small aperture problems. The first question addressed is how far should one recede from the aperture in order to justifiably use the well‐known aperture dipole approximations. Alternatively, how close may a source or a backing object be located without appreciably effecting the aperture quasistatic field distributions. The second consideration is to what distance the radiation emanating from the aperture remains collimated and how strongly is the near‐field intensity dependent upon distance. The model used for our calculation is that of a small circular aperture for which the quasistatic aperture field distributions are analytically derivable. It is presumed that this should give an indication of the near‐zone field characteristics to be expected in the general case.