AiryScheibe

Airy-Scheibe, commonly called the Airy disk, is the diffraction pattern produced by a circular aperture or lens. It consists of a bright central spot, the Airy disk, surrounded by a series of faint concentric rings. The pattern is named after George Biddell Airy, who analyzed diffraction in the 1830s.

In the ideal case of a uniformly illuminated circular pupil, the intensity distribution in the focal plane is described by a form involving the Bessel function J1. The on-axis point-spread function I(θ) is proportional to [2 J1(π D sin θ / λ) / (π D sin θ / λ)]^2, where D is the aperture diameter and λ is the light wavelength. The first minimum of the pattern occurs at an angular radius θ ≈ 1.22 λ / D. In the image plane, this corresponds to a radius r1 ≈ 1.22 λ f / D and a disk diameter of about 2.44 λ f / D, with f the focal length.

Significance is rooted in diffraction-limited imaging: the Airy disk sets the fundamental angular resolution of an optical system. According to the Rayleigh criterion, two point sources are considered resolvable when the center of one Airy disk coincides with the first minimum of the other. Real systems deviate from the ideal due to aberrations, obscurations, and bandwidth, which blur the rings and modify the effective point-spread function.

Historically, the Airy disk remains a central concept in optics, computer vision, astronomy, and microscopy as a natural limit to resolving power.