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Resolving absolute depth in circular-ranging optical coherence tomography by using a degenerate frequency comb.

Norman Lippok^1,2, Benjamin J Vakoc^1,2,3

¹Harvard Medical School, Boston, Massachusetts 02115, USA.

|May 13, 2020

Summary

This study introduces a modified circular-ranging optical coherence tomography (CR-OCT) system using a degenerate frequency comb. This innovation recovers absolute depth information, overcoming a key limitation of current CR-OCT imaging for enhanced optical coherence tomography applications.

Area of Science:

Biomedical Optics
Optical Imaging
Metrology

Background:

Fourier-domain optical coherence tomography (FD-OCT) signal bandwidth is constrained by imaging range, speed, and axial resolution.
Circular-ranging OCT (CR-OCT) decouples imaging range from signal bandwidth, enabling long-range imaging but losing absolute depth information.
Current CR-OCT systems determine relative scatterer positions, not absolute depths.

Purpose of the Study:

To introduce a modified CR-OCT system capable of recovering absolute depth information.
To utilize a degenerate frequency comb source within the CR-OCT architecture.
To maintain the RF bandwidth compression benefits of CR-OCT while enabling absolute ranging.

Main Methods:

Implementation of a modified CR-OCT system incorporating a degenerate frequency comb source.
Design and modification of existing frequency comb sources for degeneracy.
Conducting imaging studies and simulations to validate absolute ranging capabilities.

Main Results:

Demonstrated recovery of absolute depth information in CR-OCT imaging.
Showcased that the degenerate frequency comb can be generated with simple modifications to standard sources.
Validated the method through experimental imaging and computational simulations.

Conclusions:

The modified CR-OCT system successfully recovers absolute depth information.
The use of a degenerate frequency comb offers a practical solution for absolute ranging in CR-OCT.
This advancement enhances the capabilities of CR-OCT for precise depth measurements in optical coherence tomography.

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