Tomographic reconstruction of weak, replicated index structures embedded in a volume

Area of Science:

• Optical physics
• Materials science
• Nanotechnology

Background:

• Characterizing embedded index structures is crucial for optical materials like polymers and glass.
• Fabricated structures such as waveguides require precise index measurement for performance.
• Existing methods struggle with sensitivity and accuracy for weak, buried structures.

Purpose of the Study:

• To develop an optical diffraction tomography system for high-fidelity imaging of weak, embedded index structures.
• To enhance the sensitivity and accuracy of measurements in homogeneous volumes.
• To enable characterization of fabricated optical components without phase aberrations.

Main Methods:

• Demonstration of an optical diffraction tomography system.
• Replication of the target structure to form a diffraction grating.
• Coherent addition of scattering signals in the far field.
• Lensless imaging to eliminate phase aberration errors.

Main Results:

• High-fidelity cross sections of weak, deeply-buried index structures were successfully constructed.
• The system demonstrated increased sensitivity through coherent scattering addition.
• Accurate measurements were achieved in thick, homogeneous volumes without lens-induced aberrations.

Conclusions:

• The developed optical diffraction tomography system is effective for characterizing weak, embedded index structures.
• The replication technique significantly enhances imaging sensitivity and fidelity.
• This method offers a robust solution for material and device characterization in optics.