An Airy disk is a circular diffraction pattern that results from the interference of light passing through a circular aperture, such as a lens or a circular opening in an optical instrument. The Airy disk is named after British astronomer George Biddell Airy, who first described the phenomenon in the 19th century.
The Airy disk is a fundamental concept in optics and is important for understanding the behavior of light in optical systems. When light passes through a circular aperture, the diffraction pattern forms a central peak surrounded by alternating bright and dark rings. The size of the central peak and the spacing of the rings are determined by the size of the aperture and the wavelength of the light.
In an optical system, the Airy disk determines the resolving power, or the ability to distinguish fine details, of the system. The smaller the Airy disk, the greater the resolving power of the system. This makes the Airy disk an important factor in the design of optical systems, such as telescopes and microscopes, where high resolving power is desired.
In addition to its importance in optics, the Airy disk also has applications in fields such as astronomy, where it is used to determine the quality of images captured by telescopes, and in biology, where it is used to measure the size of biological structures such as cells and viruses. Understanding the properties of the Airy disk is an important area of study in physics and engineering and is fundamental to our understanding of light and its behavior in optical systems.