Toward real-time charged-particle image reconstruction using polar onion-peeling

Area of Science:

• Physical Chemistry
• Chemical Physics
• Molecular Dynamics

Background:

• Photofragment imaging experiments yield 2D projections of 3D distributions.
• Reconstructing full 3D distributions from 2D projections is crucial for understanding molecular dissociation dynamics.
• Existing methods can suffer from centerline noise and computational expense.

Purpose of the Study:

• To develop a novel, computationally efficient method for reconstructing 3D photofragment distributions from 2D projections.
• To address limitations of existing reconstruction techniques, such as centerline noise.
• To enable real-time image reconstruction during experiments.

Main Methods:

• The method employs polar coordinate onion-peeling, subtracting contributions from outside the bisecting plane at decreasing radii.
• It integrates concepts from the polar coordinate basis set expansion (pBASEX) method for generating subtraction projections.
• The approach is designed for systems with cylindrical symmetry in the expanding Newton sphere.

Main Results:

• The developed method achieves accuracy comparable to the pBASEX technique.
• It effectively eliminates centerline noise often present in Cartesian coordinate-based reconstruction methods.
• The computational efficiency allows for reconstruction of images as they are acquired.

Conclusions:

• This new method provides an accurate and computationally inexpensive way to reconstruct 3D photofragment distributions.
• It offers a significant advantage over existing techniques by eliminating centerline noise.
• The real-time reconstruction capability enhances the utility of photofragment imaging experiments.