Airy Disks, Numerical Aperture and Resolution
This tutorial explores how Airy disk sizes (at the limit of optical resolution) vary with changes in objective numerical aperture (NA) and illumination wavelength and how these changes affect the resolution (R) of the objective (lower values for R indicate increasing resolution). Operating instructions are discussed below the tutorial window.
To operate the tutorial, use the slider on the left to adjust the wavelength of illumination. The default value for wavelength is 700 nanometers (the highest wavelength available in this tutorial). As this value is decreased, note how the Airy disk size decreases (and resolution (R) increases). The slider on the right controls numerical aperture value for a hypothetical objective. At fixed wavelength, the right-hand slider will shift numerical aperture values for the objective light cone depicted just above the slider. The light cone size will increase with numerical aperture (at fixed wavelength) and produce a corresponding decrease in the size of the Airy disks (and an increase in resolution).