X-ray computed tomography using partially coherent Fresnel diffraction with application to an optical fiber

Area of Science:

• Physics
• Materials Science
• Imaging Science

Background:

• Partially coherent X-ray computed tomography (XCT) presents reconstruction challenges.
• Existing methods may produce artifacts, limiting accuracy in microscale imaging.
• Accurate reconstruction of microscale structures like optical fibers is crucial for material analysis.

Purpose of the Study:

• To develop and apply a novel reconstruction algorithm for partially coherent XCT.
• To enhance the accuracy of XCT reconstructions by including Fresnel diffraction.
• To improve the imaging of microscale objects, specifically optical fibers.

Main Methods:

• Developed a reconstruction algorithm for partially coherent XCT incorporating Fresnel diffraction.
• Applied the algorithm to a laboratory-scale, tube-based XCT instrument.
• Utilized maximum likelihood and a Bayesian method for reconstruction of a tilt series from an optical fiber.

Main Results:

• The algorithm successfully reconstructed a graded-index optical fiber at the micrometer scale.
• Inclusion of Fresnel diffraction reduced specific reconstruction artifacts.
• Bayesian prior probability distribution further minimized artifacts, leading to a more accurate reconstruction.
• The algorithm's computing time is comparable to projective methods.

Conclusions:

• The developed XCT algorithm offers a significant improvement in reconstruction accuracy for partially coherent imaging.
• The combined use of Fresnel diffraction and Bayesian methods effectively mitigates common reconstruction artifacts.
• This approach is suitable for high-resolution laboratory-scale XCT of microscale objects.