Preliminaries

Abstract

Since the 50’ s, the optical analogy has played an important rôle in shaping the research program of high-energy particle diffraction. Kirchhoff’s diffraction theory is indeed formally similar to the quantum theory of potential scattering at high energies, the so-called “eikonal^l approximation”, and the latter is the basis of the geometrical and s-channel approaches to hadronic diffraction.