To fill in some of the details in the derivation of the smallest phase increment separatin...

To fill in some of the details in the derivation of the smallest phase increment separating two resolvable Fabry-Perot fringes, that is,

satisfy yourself that

Show that Eq. (9.72) can be rewritten as

When F is large γ is small, and sin (∆δ) = ∆δ. Prove that Eq. (9.73) then follows.