Increasing the bandwidth of the light source in OCT directly improves which aspect?

• A. Lateral resolution
• B. Axial resolution
• C. Color accuracy
• D. Imaging depth

Answer: (B)

In OCT, the axial resolution is set by the coherence length of the light, which depends on how broad the spectrum is. A broader bandwidth means the light has a shorter coherence length, so the system can distinguish reflectors that are closer together along the depth (z) direction. That’s why increasing bandwidth directly improves axial resolution.

Lateral resolution, on the other hand, is determined by the focusing optics and numerical aperture, not the spectral width. Imaging depth is limited mainly by scattering, absorption, and the system’s sensitivity, not bandwidth. Color accuracy isn’t a factor in OCT, since the technique isn’t resolving color information in tissue.