  In this work we present a novel approach to the ray optics limit: we rewrite
the dynamical Maxwell equations in Schr\"odinger form and prove Egorov-type
theorems, a robust semiclassical technique. We implement this scheme for
periodic light conductors, photonic crystals, thereby making the quantum-light
analogy between semiclassics for the Bloch electron and ray optics in photonic
crystals rigorous. Our main results, Theorems 3.3 and 4.1, give a ray optics
limit for quadratic observables and, among others, apply to local averages of
energy density, the Poynting vector and the Maxwell stress tensor. Ours is the
first rigorous derivation of ray optics equations which include all sub-leading
order terms, some of which are also new to the physics literature. While the
ray optics limit we prove initially (Theorem 3.3) applies to photonic crystals
of any topological class, we also consider the ray optics limit for real
electromagnetic fields propagating in non-gyrotropic photonic crystals. Such an
extension is non-trivial, because the ray optic limit for real fields is
necessarily a multiband problem.
