Interleaved optical coherence tomography.

Area of Science:

• Biomedical Optics
• Optical Imaging Technology

Background:

• Swept source optical coherence tomography (SS-OCT) systems face limitations in imaging speed, hindering real-time dynamic observation and 3D imaging.
• Existing methods for enhancing OCT imaging speed often involve complex configurations or faster, more expensive laser sources.

Purpose of the Study:

• To introduce and validate a novel, cost-effective technique called interleaved optical coherence tomography (iOCT) for enhancing SS-OCT imaging speed.
• To demonstrate that iOCT can achieve high effective A-scan rates and improve imaging capabilities for dynamic processes and 3D imaging.

Main Methods:

• Developed iOCT by integrating a virtually imaged phase array (VIPA) as a multi-band demultiplexer in the sample arm of a traditional OCT system.
• Acquired data from multiple lateral positions simultaneously during a single wavelength sweep using a single detector.
• Utilized spectral encoding to convert coherence length into higher imaging speed, independent of source speed or center wavelength.

Main Results:

• Achieved image speed enhancement factors of up to 12, 6, and 10 with 10 kHz, 20 kHz, and 100 kHz sources, respectively.
• Demonstrated effective A-scan rates of 120 kHz, 120 kHz, and 1 MHz for B-scan imaging with high sensitivity (up to 82.5 dB).
• Successfully performed 3D biological imaging and captured faster dynamics than traditional OCT B-scan imaging.

Conclusions:

• iOCT offers a significant enhancement in imaging speed for SS-OCT systems without compromising axial resolution or requiring faster laser sources.
• The technique is compatible with existing SS-OCT configurations, requiring only a modification in the sample arm.
• iOCT presents a promising complementary approach to current high-speed OCT research, particularly beneficial for systems with slower sweep rates or those aiming to enhance coherence length for faster imaging.