ABSTRACT
Diffraction is a phenomenon originating from the wave nature of light that occurs in a light beam of which amplitude is distributed to an area in the cross-section that is perpendicular to the direction of propagation. The spherical wave can be derived via the polar coordinates, the cylindrical wave can be derived from the cylindrical coordinate system. The chapter considers diffraction at the Fraunhofer region, but actually the propagation of the Gaussian beam preserves the Gaussian form even in the Fresnel region. When focusing of parallel rays of light by means of the wave front, the ray will propagate perpendicular to the wave front of the optical wave, the parallel rays of light are considered to represent the propagation of the plane wave. The chapter considers the amplitude distribution after the propagation at a distance of d in the z-direction of a free-space wavepropagating approximately in the z-direction as an amplitude distribution in the x'y' plane.
