Angular aperture

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

Super wide angle lens arrangement for infrared applications

Abstract: The invention relates to high resolution, super wide angle optical assemblies for IR imaging. More particularly, a wide-angle optical assembly for an IR camera is described, comprising a lens system consisting of an object-side lens (2) and an image-side lens (3), and an aperture stop (1) on the object-side of the assembly, wherein: the object-side lens (2) and the image-side lens (3) are positive meniscus lenses; all centers of vertex radii of the lens surfaces are oriented towards the object-side, defining for each lens a concave surface and a convex surface; the thickness (8) of the object-side lens (2) is larger than 0,60 EFL; the thickness (9) of the image-side lens (3) is between 0,30 EFL and 0,70 EFL; 0.95 < BFL / EFL < 1.2; and, the EFL amounts to between 55% and 75% of the image plan diagonal. This assembly combines a wide field of view with the high spatial resolution needed to fully exploit state of the art 17 μm pixel pitch IR detectors. This is achieved using only two lenses, thus offering a cost advantage over existing many-lenses assemblies.

Dynamic aperture holographic multiplexing

Abstract: Systems and methods for dynamic aperture holographic multiplexing are disclosed. One example process may include recording a set of holograms in a recording medium by varying both the reference beam angular aperture and the signal beam angular aperture. The angular aperture of the signal beam may be dynamically changed such that the closest edge of each signal beam angular aperture is selected to be a threshold angle different than the angular aperture of the reference beam used to record it. In some examples, the dynamic aperture holographic multiplexing process may include dynamic aperture equalization to reduce cross-talk, to improve error correction parity distribution for improved recovery transfer rate, to provide multiple locus aperture sharing for increased recording density, and to provide polarization multiplexed shared aperture multiplexing for increased transfer rate in both recording and recovery.

Use of diverging apertures to minimize the edge scatter in passive scattering proton therapy

Abstract: The purpose of this study was to evaluate the use of diverging-cut aperture to minimize collimator contamination in proton therapy. Two sets of apertures with nondivergent and divergent edge were fabricated to produce a 10 cm × 10 cm field at the radiation isocenter of a single-room proton therapy unit. Transverse profiles were acquired in a scanning water tank with both aperture sets. Up to 9.5% extra dose was observed from aperture scattering near the field edges with the nondivergent aperture set at 2 cm above the water surface and remained 3.0% at depth of 10 cm. For the divergent set, the contamination was reduced to less than 3.5% and 1.3%, respectively. Our study demonstrated that scattering from apertures contaminated the dose distribution near the field edge at shallow depth. A diverging-cut aperture was capable of reducing the contamination and is recommended for use in passive scattering proton therapy, especially when critical organs are lateral and proximal to the target at shallow depth.

Diffraction of a focused wave by an aperture: a new perspective

Abstract: A new approach for calculating the field in the focal region along lines through the focal point of a lens is presented. In particular, the method is applied to a circular aperture. It is also applied to other shaped apertures, including circular sectors or segments, such as a semicircular aperture or Hilbert mask, and to polygonal shapes. The diffracted field is calculated by a one-dimensional Fourier transform, and can be used for accurate calculation at observation points distant from the focus. The approach gives new insight to appreciating the asymptotic behavior of the diffracted field, and the existence of intensity zeros, for different aperture shapes.