Quantitative shadowgraphy and proton radiography for large intensity modulations

TL;DR

This paper introduces a new computational geometry method to extract quantitative data from shadowgraphy and proton radiography images, enabling accurate electric and magnetic field measurements in high-energy-density plasmas.

Contribution

The novel approach allows for quantitative analysis from shadowgrams, overcoming non-linear challenges, and is validated with benchmark tests showing less than 10% error.

Findings

Accurately retrieves parameters with <10% error

Effective even with caustics present

Robust to experimental noise and simple pre/post-processing

Abstract

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 non-linear nature of the process. Here, a novel method to retrieve quantitative information from shadowgrams, based on computational geometry, is presented for the first time. This process can 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 post-processing techniques. This adds a powerful new tool for research in various fields in engineering and physics for both techniques.