Direct inversion of deflectometry data using an electrostatic plasma model

J. R. Davies, P. V Heuer

Laboratory for Laser Energetics, Rochester, NY

A. F. A. Bott

Princeton University, Princeton, NJ

Deflectometry encompasses charged particle radiography and shadowgraphy. We propose a new method for the direct inversion of deflectometry data using an electrostatic plasma model, and compare it to a new Monge-Ampère code and an existing power-diagram code. The measured and source intensities are represented by fixed ions and mobile electrons subject to drag. The displacement of the electrons at equilibrium determines the path-integrated transverse deflection force. The decrease in energy provides a measure of convergence. We have implemented two approaches: PIC (particle in cell) and Lagrangian fluid. A series of test cases were run to validate and compare the algorithms. Only the PIC code obtained a solution to every case. The Monge--Ampère code was by far the fastest, but failed to converge for strong modulations. The power-diagram code was by far the slowest and failed to obtain a solution in cases with large peaks in the measured intensity, but was more accurate than the other codes for a test with a mesh placed between the source and the object.