POWER TRANSPORTED BY A CIRCULARLY SYMMETRIC LASER-BEAM TO A CIRCULAR TARGET

A new mathematical technique is applied to the consumption of the power transported by a laser beam to a circular target. The authors give an explicit expression for it as the scalar product between an array of values of the amplitude at the source plane and the same array as transformed by a Hermitian operator. This operator does not depend on the signal at the input plane but only on the geometry of the problem and therefore it can be computed only once and then it can be applied to several beam shapes. Both intensity integration at the target plane and Fresnel integration are avoided. The accuracy of the method is shown by comparison to the analytical solution for the case of the Gaussian laser beam.