Tomographic reconstruction techniques optimized for velocity-map imaging applications.

Area of Science:

• Photochemical Dynamics
• Chemical Physics
• Spectroscopy

Background:

• Tomographic reconstruction is vital for extracting 3D information from image projection data in various scientific fields.
• In photochemical dynamics, it enables reconstruction of charged particle momentum distributions after photodissociation or photoionization events.
• Existing generalized tomographic methods, based on Fourier-slice theorem and filtered back-projection, are suboptimal for these applications.

Purpose of the Study:

• To evaluate alternative tomographic reconstruction strategies for velocity-map imaging in photochemical dynamics.
• To introduce and demonstrate the advantages of the simultaneous iterative reconstruction technique (SIRT) and Hankel Transform Reconstruction (HTR).
• To establish a lower bound on the minimum projections required for reliable 3D reconstruction.

Main Methods:

• Discussion and application of simultaneous iterative reconstruction technique (SIRT).
• Introduction and implementation of Hankel Transform Reconstruction (HTR).
• Comparison of HTR and SIRT against commonly used filtered back-projection algorithms in velocity-map imaging.

Main Results:

• SIRT and HTR demonstrate clear advantages over conventional methods for reconstructing 3D charged particle momentum distributions.
• HTR significantly outperforms existing approaches, offering superior accuracy and efficiency.
• HTR establishes a new, considerably lower bound for the minimum number of projections necessary for reliable 3D reconstruction.

Conclusions:

• Alternative tomographic methods, particularly HTR, provide superior performance for velocity-map imaging in photochemical dynamics.
• The reduced projection requirement with HTR makes advanced 3D imaging more accessible and efficient for experimentalists.
• This work advances the capabilities of tomographic imaging in the study of photochemical processes.