Flyscan terahertz multi-plane lensless imaging with suppressed coherent noise

Area of Science:

• Optics and Photonics
• Terahertz (THz) Imaging
• Biomedical Imaging

Background:

• Coherent lensless imaging faces challenges with coherent noise and twin-image artifacts.
• In the terahertz (THz) range, noise includes parasitic interference fringes and edge diffraction.
• Existing methods struggle with noise suppression and achieving high-resolution imaging in THz frequencies.

Purpose of the Study:

• To develop a novel lensless imaging technique for high-quality, rapid, complex-valued THz imaging.
• To suppress Fabry-Pérot (F-P) interference fringes and edge diffraction in THz imaging.
• To achieve subwavelength resolution in THz imaging for potential biomedical applications.

Main Methods:

• A flyscan THz multi-plane lensless imaging technique is proposed.
• Averaging diffraction patterns over axial shifts suppresses F-P interference fringes.
• Normalization addresses edge diffraction and non-uniform illumination; multi-plane configuration tackles twin-image artifacts.
• Image reconstruction refined using multi-plane alternating projection and total variation regularization algorithms.

Main Results:

• The technique achieves subwavelength resolution (88 µm at 2.52 THz).
• High-quality, full-field, and rapid complex-valued THz imaging is demonstrated.
• Successful imaging of mouse brain tissue showcases biomedical potential.

Conclusions:

• The proposed flyscan THz multi-plane lensless imaging technique effectively suppresses coherent noise and artifacts.
• The method enables high-resolution, rapid THz imaging with potential for biomedical applications.
• Refined reconstruction algorithms further enhance image quality and resolution.