Light Diffraction Pattern

This is the light diffraction pattern at the back focal plane of a 10X, NA 0.25, microscope objective when viewing a diffraction of grating of 1.9 micrometers with brightfield illumination. Only the blue and some of the green diffraction maxima are collected, which indicates that the resolution limit for this objective is 1.9 micrometers for blue light and larger for longer wavelengths of light.