Ultra-high-speed optical coherence tomography with a stretched pulse supercontinuum source.

Area of Science:

• Biomedical Optics
• Optical Imaging
• Metrology

Background:

• Fourier-domain optical coherence tomography (FD-OCT) is a powerful non-invasive imaging technique.
• Achieving higher imaging speeds in FD-OCT is crucial for real-time applications and reducing motion artifacts.
• Existing high-speed FD-OCT methods often require complex setups or active wavelength tuning.

Purpose of the Study:

• To introduce a new, simplified high-speed FD-OCT scheme.
• To demonstrate an ultrahigh axial-line scanning rate using a novel light source.
• To achieve high axial resolution without active sweep re-calibration.

Main Methods:

• Utilized a supercontinuum source generating a wide spectrum (1,200-1,550 nm).
• Employed group-velocity dispersion in a fiber to stretch short pulses into 70-ns long pulses.
• Acquired spectral interferograms in the time domain and converted them to the spectral domain using a pre-calibrated time-to-wavelength relation.
• Implemented the stretched-pulse OCT (SP-OCT) scheme.

Main Results:

• Demonstrated an ultrahigh axial-line scanning rate of 5 MHz.
• Achieved an axial resolution of 8 micrometers.
• The frequency-sweeping mechanism was passive, eliminating the need for re-calibration.

Conclusions:

• The stretched-pulse OCT (SP-OCT) scheme offers a simplified approach to ultrahigh-speed FD-OCT.
• This method enables high-speed imaging with excellent axial resolution.
• The passive nature of the frequency-sweeping mechanism enhances system stability and ease of use.