The Huygens integral, or Green’s function, for paraxial beam propagation in a generalized lenslike medium is derived as a Feynman path integral involving a summation over real rays. This formulation provides a physically intuitive understanding of the structure of the Green’s function. The path integral is evaluated by introducing in a consistent manner the notion of complex rays, and the familiar result for the Huygens integral in terms of the complex ABCD matrix of the medium is obtained.
© 1987 Optical Society of America
E. M. Wright and J. C. Garrison, "Path-integral derivation of the complex ABCD Huygens integral," J. Opt. Soc. Am. A 4, 1751-1755 (1987)