Numerical model for tomographic image formation in transmission x-ray microscopy.

Area of Science:

• X-ray microscopy
• Image reconstruction
• Optical physics

Background:

• Accurate tomographic reconstruction in transmission x-ray microscopy (TXM) is crucial for analyzing thick samples.
• Factors like partial coherence, sample thickness, and depth-of-focus can degrade reconstruction accuracy.
• Understanding these influences is key to optimizing TXM systems for quantitative imaging.

Purpose of the Study:

• To develop and present a numerical image-formation model for investigating TXM.
• To analyze the impact of partial coherence, sample thickness, and depth-of-focus on tomographic reconstruction accuracy.
• To optimize TXM systems for quantitative imaging of thick specimens.

Main Methods:

• A numerical model combining finite difference techniques for wave propagation and Fourier methods.
• Integration of a ray-tracing model to identify stray light sources in zone plate-based TXM.
• Simulation of image formation considering partial coherence, sample thickness, and depth-of-focus.

Main Results:

• The depth-of-focus in tomographic reconstructions is highly dependent on the degree of coherence.
• The reconstructed local absorption coefficient accuracy is also significantly influenced by the optical system's coherence.
• The model allows for the optimization of TXM parameters for improved imaging of thick objects.

Conclusions:

• Partial coherence is a critical factor affecting depth-of-focus and quantitative accuracy in TXM.
• The developed numerical model provides a tool for optimizing TXM systems for advanced applications.
• Accurate modeling is essential for reliable quantitative tomographic imaging of complex, thick samples.