Matrix representation of axisymmetric optical systems including spatial filters

A matrix approach is presented that allows one to describe a complex optical system by a matrix relating the field at the output plane to the field at the input one. The elements of the optical system may be all those characterized by an ABCD ray-transfer matrix, as well as any kind of film which introduces a wavefront modulation that can be described by a complex radial transmittance function. These include, as particular cases, stops and limiting apertures. No integral has to be computed. The method holds only for circularly symmetric optical systems and laser beams.