What are the axial length resolutions for spectral domain and time domain OCT?

What are the axial length resolutions for spectral domain and time domain OCT?

• A. SD: 8-10 microns; TD: 3-7 microns
• B. SD: 3-7 microns; TD: 8-10 microns
• C. SD: 1-2 microns; TD: 2-3 microns
• D. SD: 10-12 microns; TD: 12-14 microns

Answer: (B)

Axial resolution in OCT is set by the light’s coherence length, which gets shorter as the source bandwidth increases. Spectral-domain OCT uses a broad spectrum detected with a spectrometer and processed with a Fourier transform, allowing very broad bandwidth sources to be utilized. This gives finer depth discrimination, typically around 3–7 microns. Time-domain OCT relies on scanning the reference arm with a comparatively narrower bandwidth source, so its axial resolution is poorer, usually about 8–10 microns. So the statement that spectral-domain is about 3–7 microns and time-domain about 8–10 microns reflects their typical performance.

Axial resolution in OCT is set by the light’s coherence length, which gets shorter as the source bandwidth increases. Spectral-domain OCT uses a broad spectrum detected with a spectrometer and processed with a Fourier transform, allowing very broad bandwidth sources to be utilized. This gives finer depth discrimination, typically around 3–7 microns. Time-domain OCT relies on scanning the reference arm with a comparatively narrower bandwidth source, so its axial resolution is poorer, usually about 8–10 microns. So the statement that spectral-domain is about 3–7 microns and time-domain about 8–10 microns reflects their typical performance.