Within optical coherence tomography $($OCT$)$ systems, the axial resolution is determined by the

bandwidth of the light source. If a system was designed with the following two sources

Source$1$: center wavelength $=800$ nm$,$ bandwidth $=50$nm

Source$2$: center wavelength $=800$ nm$,$ bandwidth $=100$nm

a$)$ which would provide higher axial resolution and why? $[$Hint$,$ axial resolution is

proportional to the coherence length, $$l c $].[4$ points$]$

b$)$ to design an imaging system with high lateral resolution, would you use a low or high NA

lens? Why? $[4$ points$]$