Return to Eq. (12.21) and separate it into two terms representing a coherent and an incohe...

Return to Eq. (12.21) and separate it into two terms representing a coherent and an incoherent contribution, the first arising from the superposition of two coherent waves with irradiances of  and  having relative phase of α12(T), and the second from the superposition of incoherent waves of irradiance  and . Now derive expressions for Icoh/Iincoh and for Iincoh/Itotal, Discuss the physical significance of this alternative formulation and how we might view the visibility of fringes in terms of it.