Focus-extension by depth-encoded synthetic aperture in Optical Coherence Tomography

Area of Science:

• Biomedical Optics
• Optical Engineering
• Medical Imaging

Background:

• Optical Coherence Tomography (OCT) provides depth-resolved scattering information.
• Axial resolution in OCT is consistent, but lateral resolution degrades beyond the Rayleigh range.
• Maintaining lateral resolution over a large depth range is a significant challenge in OCT.

Purpose of the Study:

• To introduce a novel method for extending the depth-of-focus in OCT.
• To improve and maintain lateral resolution over an extended imaging depth.
• To overcome the limitations imposed by the Rayleigh range in OCT imaging.

Main Methods:

• Implementation of a depth-encoded synthetic aperture detection scheme.
• Insertion of an annular phase plate in the sample arm light path.
• Coherent summation of three phase-manipulated, depth-encoded images.

Main Results:

• The proposed method successfully extends the depth range for sharp focus.
• Lateral resolution is maintained over a five times larger depth range compared to conventional OCT.
• Reconstructed images exhibit improved focus consistency across greater depths.

Conclusions:

• The novel OCT method effectively enhances depth-of-focus and maintains lateral resolution.
• This technique offers a significant improvement for OCT imaging applications requiring extended depth visualization.
• The depth-encoded synthetic aperture approach provides a viable solution to overcome Rayleigh range limitations.