The Rayleigh limit (also known as the Abbe diffraction limit), although originally applied to image resolution, can be viewed in reverse, and dictates that the irradiance (or "intensity") of any electromagnetic wave (such as a microwave or laser beam) will be reduced as the beam diverges over distance at a minimum rate inversely proportional to the aperture size. The larger the ratio of a transmitting antenna's aperture or laser's exit aperture to the wavelength of radiation, the more can the radiation be concentrated in a compact beam