Airy Disk Size Calculator
Calculate the Airy disk radius and Abbe diffraction limit based on wavelength and numerical aperture.
Airy radius (first dark ring)
0.353 µm
0.610 λ/NA
Airy disk diameter (1 AU)
0.706 µm
1.22 λ/NA
Intensity FWHM
297.9 nm
0.514 λ/NA
Abbe limit λ/2NA
289.5 nm
3455 line pairs/mm
Uniformly filled circular pupil, no aberrations, scalar theory. 83.8 % of the light falls inside the first dark ring. Above NA ≈ 0.9 the vector focus differs: with linear polarization it is ≈ 30 % wider along the polarization and slightly narrower across it at NA 1.4; unpolarized or circular light widens it ≈ 10–20 %. An NA above 1 needs an immersion medium.
Diffraction-limited spot size vs NA
- Airy radius (first zero)
- Airy FWHM
- Abbe λ/2NA
- Current
Airy pattern and encircled energy
- Intensity [2J₁(v)/v]²
- Encircled energy
Model and references
Textbook approximation. A standard approximation from the literature (for example paraxial, plane-wave or Gaussian-beam), valid within the range the page states. About the tiers
Scalar Airy pattern of an aberration-free, uniformly filled circular pupil. Above NA ≈ 0.9 the vector focus differs: linear polarization widens it ≈ 30 % along the polarization at NA 1.4 (slightly narrower across), unpolarized or circular light ≈ 10–20 %; a Gaussian-filled pupil gives a wider, ringless spot.
- Born M., Wolf E. (2019). Principles of Optics, 7th ed., §8.5.2. Cambridge University Press. Airy pattern [2J₁(v)/v]² and encircled energy 1 − J₀² − J₁². doi:10.1017/9781108769914
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