Resolution Calculator
Abbe and Rayleigh lateral resolution limits for diffraction-limited imaging.
NA = n sin α, so NA must stay below the medium index n.
Results
Abbe: the finest grating period an objective passes with oblique illumination filling the aperture.
Rayleigh: two incoherent points resolved when one sits on the other's first dark ring (26 % dip).
Axial: the widefield on-axis PSF; n sets the cone angle, so it widens as NA nears n.
Lateral resolution vs NA (different wavelengths)
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
Classical two-point and grating criteria for incoherent, aberration-free imaging with a uniformly filled pupil. The axial FWHM is the widefield on-axis PSF; NA must stay below the medium index. Scalar: the vector focus above NA ≈ 0.9 isn't modelled.
- Born M., Wolf E. (2019). Principles of Optics, 7th ed., §8.6.2. Cambridge University Press. Rayleigh resolving power 0.61 λ/NA. doi:10.1017/9781108769914
- Wilhelm R., Gröbler B., Gluch M., Heinz H. (2003). Confocal Laser Scanning Microscopy: Principles. Carl Zeiss. Axial FWHM 0.88 λ/(n − √(n² − NA²)).