Kasim Muhammad Firmansyah, Ceurvorst Luke, Ratan Naren, Sadler James, Chen Nicholas, Sävert Alexander, Trines Raoul, Bingham Robert, Burrows Philip N, Kaluza Malte C, Norreys Peter
John Adams Institute, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, United Kingdom.
Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
Phys Rev E. 2017 Feb;95(2-1):023306. doi: 10.1103/PhysRevE.95.023306. Epub 2017 Feb 16.
Shadowgraphy is a technique widely used to diagnose objects or systems in various fields in physics and engineering. In shadowgraphy, an optical beam is deflected by the object and then the intensity modulation is captured on a screen placed some distance away. However, retrieving quantitative information from the shadowgrams themselves is a challenging task because of the nonlinear nature of the process. Here, we present a method to retrieve quantitative information from shadowgrams, based on computational geometry. This process can also be applied to proton radiography for electric and magnetic field diagnosis in high-energy-density plasmas and has been benchmarked using a toroidal magnetic field as the object, among others. It is shown that the method can accurately retrieve quantitative parameters with error bars less than 10%, even when caustics are present. The method is also shown to be robust enough to process real experimental results with simple pre- and postprocessing techniques. This adds a powerful tool for research in various fields in engineering and physics for both techniques.
阴影成像技术是一种在物理和工程等各个领域广泛用于诊断物体或系统的技术。在阴影成像中，一束光束被物体偏转，然后在一定距离外的屏幕上捕获强度调制。然而，由于该过程的非线性性质，从阴影图本身获取定量信息是一项具有挑战性的任务。在此，我们提出一种基于计算几何从阴影图中获取定量信息的方法。该过程也可应用于质子射线照相术，用于高能密度等离子体中的电场和磁场诊断，并且已以环形磁场等作为对象进行了基准测试。结果表明，即使存在焦散，该方法也能准确检索定量参数，误差条小于10%。该方法还被证明足够稳健，能够通过简单的预处理和后处理技术处理实际实验结果。这为工程和物理各个领域的研究为这两种技术增添了一个强大的工具。
