Novel approaches for the use of Coded Apertures in high-energy high-resolution imaging systems

用相机进行x射线成像最常见的是用针孔孔径进行；穿孔在不透明介质中的单个穿孔可达到的分辨率和通量都受到射孔尺寸的限制，导致在单射孔孔径中两者之间存在固有的折衷。多射孔被称为“编码射孔”，通过在编码几何结构中使用大量小尺寸射孔，克服了这一缺点。然而，随着源规模的减小和能量的增加（例如激光尾流场加速x射线源和内部约束聚变过程中产生的中子），任何形式的针孔孔径的应用变得不那么常见。这是由于光学不透明度所需的大衬底厚度加上需要小穿孔，导致宽高比，制造和实施的复杂性。该项目旨在增加基于编码孔径的成像系统在高能高分辨率应用中的使用范围。这将通过在新方法中利用现有编码孔径理论的次要特性来实现，以减少先前的限制，如衬底不透明度，大探测器面积和光谱选择性相机。这将扩大到包括必要的变化，以允许多兆电子伏成像的微米级物体和源。在项目期间，该成像系统将应用于x射线照相、断层扫描和物体的后向散射，以及聚变反应过程中的中子内爆成像。然而，可能的应用可以延伸到医学成像、实验室天体物理实验和端口安全扫描。

X-ray imaging with a camera is most commonly performed with a pinhole aperture; a single perforation within some opaque medium. Both the attainable resolution and the flux are limited by the perforation size, leading to an inherent compromise between the two in single-perforation apertures. Multi-perforation apertures, dubbed "coded apertures", overcome this compromise using a large number of small-sized perforations in a coded geometry. However, as sources decrease in scale and increase in energy (e.g. laser wakefield acceleration x-ray sources and neutrons generated during internal confinement fusion) the application of any form of pinhole aperture becomes less common. This is due to the large substrate thickness required for optical opacity coupled with the necessity for small perforations causing aspect ratio, manufacture, and implementation complications. This project aims to increase the scope of use for coded aperture based imaging systems for high-energy high-resolution applications. This will be achieved by utilising secondary properties of existing coded aperture theory in novel approaches to reduce previous constraints such as substrate opacity, large detector area, and spectrally selective cameras. This will then be expanded to include the changes necessary to allow multi-MeV imaging of micron-scale objects and sources. During the project, the imaging system will be applied to x-ray radiography, tomography, and backscatter of objects, as well as imaging neutron implosions during fusion reactions. However, the possible applications could reach as far as medical imaging, laboratory astrophysics experiments, and scanning for port security.