This volume aims to familiarize the reader with basic concepts of light propagation in the simplest class of media: linear, homogenous, dispersionless, and isotropic. After a review of Maxwell's equations in both integral and differential forms, the book describes the field propagation from elementary sources (dipoles) and in free space, in 1D, 2D, and 3D. Next, the material covers diffraction of light by a 2D screen, with various levels of approximations, emphasizing the wavevector space calculations. The ABCD matrix propagation is introduced as an efficient tool for both ray optics and Gaussian beam propagation. The volume ends with a chapter on propagation of field correlations, generalizing the coherence concepts introduced in Volume 1.Key Features: A homogeneous, self-consistent reference that covers this interdisciplinary field.Books are intended to be used as reference for a two-semester course on Principles of Biophotonics.Aim is not only to provide a "how to" user guide for these techniques, but to clearly present the optics foundation that allows them to function.