Axial resolution in OCT is determined by which property?

Axial resolution in OCT is determined by which property?

• A. Wavelength of light
• B. Bandwidth of light source
• C. Detector sensitivity
• D. Scan speed

Answer: (B)

Axial resolution in OCT comes from the coherence length of the light, which is determined mainly by how broad the light’s spectrum is. A wider spectral bandwidth means more wavelengths contributing to the interference signal, which shortens the coherence length and lets the system distinguish reflections that are closer in depth. The approximate relationship shows that axial resolution scales with the ratio of the square of the central wavelength to the bandwidth: larger Δλ (broader bandwidth) gives smaller Δz (better resolution). The central wavelength does affect the absolute depth scale a bit, but it’s the bandwidth that sets how finely you can resolve features along the depth axis. Detector sensitivity affects signal-to-noise but not the intrinsic resolving capability, and scan speed impacts how quickly you acquire data (and can introduce motion artifacts) rather than improving depth resolution.

Axial resolution in OCT comes from the coherence length of the light, which is determined mainly by how broad the light’s spectrum is. A wider spectral bandwidth means more wavelengths contributing to the interference signal, which shortens the coherence length and lets the system distinguish reflections that are closer in depth. The approximate relationship shows that axial resolution scales with the ratio of the square of the central wavelength to the bandwidth: larger Δλ (broader bandwidth) gives smaller Δz (better resolution). The central wavelength does affect the absolute depth scale a bit, but it’s the bandwidth that sets how finely you can resolve features along the depth axis. Detector sensitivity affects signal-to-noise but not the intrinsic resolving capability, and scan speed impacts how quickly you acquire data (and can introduce motion artifacts) rather than improving depth resolution.