Lens-System Diffraction Integral Written in Terms of Matrix Optics*

This paper deals with the propagation of coherent light through lens systems; it relates diffraction theory to ray optics. A diffraction integral is derived which relates the electromagnetic fields on the input plane of a lens system to those on its output plane. The kernel of the diffraction integral is written in terms of the elements of the ray matrix that describes the complete lens system; that kernel indicates a connection between ray optics and diffraction theory. It also provides a simple method for writing the diffraction integral for a lens system. The results are limited to the paraxial-ray approximation, but apply to symmetric and asymmetric lens systems. In the case of asymmetric systems, i.e., those containing rotated elliptical or cylindrical lenses, the ray-matrix formalism is extended so as to use a single fourth-order matrix. The diffraction integrals derived are applied to optical spatial filtering, optical-beam waveguides, optical resonators, and holography.