Diffraction of a Gaussian light beam at the right-angle edges of a plate and the interference pattern in the shadow region

A circular Gaussian beam of monochromatic laser radiation is normally incident to the plane of a right-angle thin metal plate and diffracts at the edges of the plate angle. It is revealed that two main fragments of a composite diffracted wave with cylindrical wave fronts whose axes are mutually orthogonal occur and interfere with each other in the shadow region behind the plate. This is found from the characteristic interference pattern on a flat screen behind the plate. This interference pattern consists of intensive curvilinear, wedge-shaped bands that are located symmetrically in pairs with respect to the bisector of the direct central angle of the circular shadow sector.