THz phase-contrast computed tomography based on Mach-Zehnder interferometer using continuous wave source: proof of...

Area of Science:

• Terahertz (THz) imaging and spectroscopy
• Medical imaging and diagnostics
• Materials science and characterization

Background:

• Traditional computed tomography (CT) methods often lack sensitivity to subtle material variations.
• Phase contrast imaging offers enhanced sensitivity to material properties compared to absorption-based methods.
• Terahertz (THz) frequencies provide unique penetration and contrast mechanisms for various materials.

Purpose of the Study:

• To develop and demonstrate a novel terahertz computed tomography (CT) method utilizing phase contrast.
• To reconstruct the spatial distribution of refractive indices from phase-shift data.
• To evaluate the imaging capabilities, including artifact immunity, quantitative measurement, and selective detection.

Main Methods:

• Implementation of a phase modulation technique using a Mach-Zehnder interferometer with a continuous wave (CW) THz source (0.54 THz).
• Acquisition of projection data using a first-generation CT setup with translational and rotational scans.
• Reconstruction of refractive index maps from phase-shift projections.

Main Results:

• Successful reconstruction of refractive index distribution in phantom samples.
• Demonstration of artifact-immune imaging capabilities.
• Validation of quantitative measurement and selective detection properties.

Conclusions:

• The proposed phase-contrast THz CT method is a viable technique for high-contrast material imaging.
• This approach enables quantitative assessment of material properties and selective detection.
• The method holds potential for applications in materials science, security screening, and non-destructive testing.