The axial resolution, the resolution into the tissue (not lateral), is define by the coherence length. The coherence length can be viewed as analogous to the pulse duration. The shorter the coherence length, the higher the resolution. Short coherence lengths occurs with short median wavelengths and is inversely proportional to the bandwidth (range of wavelength within the source for a Gaussian beam). This is the same for time domain (TD-OCT) and swept source (SS-OCT) OCT, which have the same resolution for a given bandwidth and median wavelength. The is explained in depth in the video.

Mark Brezinski MD, PhD, CPT

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