That formula is anaverage of the two Rayleigh-Sommerfeld formulas for this phenomenon and is named for Kirchhoff.
This phenomenon does not occur in the central core of Bessel beams. Abbe's theory of imageformation involves this phenomenon happening twice, which is equivalent to image formationinvolving two Fourier transforms. One formula for this phenomenon is an approximate scalarsolution of the Helmholtz equation and includes a term for the inclination factor. That formula is anaverage of the two Rayleigh-Sommerfeld formulas for this phenomenon and is named for Kirchhoff.The (*) far-field type of this phenomenon is named after Fraunhofer, and the most widely used theory insolving problems involving this phenomenon is the Huygens-Fresnel principle. For 10 points, name thisphenomenon demonstrated in Young's double slit experiment that is defined as the bending of wavesaround small obstacles and the spreading out of waves beyond small openings.
This phenomenon does not occur in the central core of Bessel beams.
diffraction