# Diffraction-limited angular resolution calculator

## About this calculator

This calculator computes the diffraction-limited angular resolution of an optical system, such as a telescope or the human eye. Because of diffraction even an aberration-free optical system images a point source not as a point but as an Airy pattern, whose central area is called the Airy disk. Two adjacent point sources are resolved by the optical system as long as their Airy disks do not overlap too much. This calculator is based on the Rayleigh criterion, which states that the Airy disks should be at least one radius apart. The radius of an Airy disk is the distance from the center to the first zero. Mathematically, the minimum angle that can be resolved based on this criterion is

where $\lambda$ is the wavelength of light and $D$ is the aperture of the optical system.