Airy disk The circular intensity maximum at the center of an Airy pattern, which is the diffraction pattern formed when imaging a point source. Synonyms: Airy disc Related MicroscopyU Article Numerical Aperture and Image Resolution The image formed by a perfect, aberration-free objective lens at the intermediate image plane of a microscope is a diffraction pattern produced by spherical waves exiting the rear aperture and converging on the focal point. This tutorial explores the effects of objective numerical aperture on the resolution of the central bright disks present in the diffraction pattern, commonly known as Airy disks.