title: Quantitative shadowgraphy and proton radiography for large intensity modulations.
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 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.
authors.affiliation: John Adams Institute, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, United Kingdom.
authors.forename: Muhammad Firmansyah
authors.initials: MF
authors.lastname: Kasim
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
authors.forename: Luke
authors.initials: L
authors.lastname: Ceurvorst
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
authors.forename: Naren
authors.initials: N
authors.lastname: Ratan
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Sadler
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Chen
authors.affiliation: Institut für Optik und Quantenelektronik, Abbe-Center of Photonics, Friedrich-Schiller-Universität, 07743 Jena, Germany.|Helmholtz-Institut Jena, Friedrich-Schiller-Universität, 07743 Jena, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Sävert
authors.affiliation: STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom.
authors.forename: Raoul
authors.initials: R
authors.lastname: Trines
authors.affiliation: STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Bingham
authors.affiliation: John Adams Institute, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, United Kingdom.
authors.forename: Philip N
authors.initials: PN
authors.lastname: Burrows
authors.affiliation: Institut für Optik und Quantenelektronik, Abbe-Center of Photonics, Friedrich-Schiller-Universität, 07743 Jena, Germany.|Helmholtz-Institut Jena, Friedrich-Schiller-Universität, 07743 Jena, Germany.
authors.forename: Malte C
authors.initials: MC
authors.lastname: Kaluza
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.|STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Norreys