Diffraction Limits

The diffraction limited resolution of a perfect optical system is defined by the diameter of the optics and the wavelength of interest. A large optical system has higher resolving capability and a shorter wavelength has less diffraction. 

When selecting a set of test targets, the limiting resolution will generally be defined by the smaller of the two optics, i.e. the camera lens or the collimator clear aperture. However, camera resolutions can exceed the nominal diffraction limit when image enhancement or multiple scanning techniques are employed.

This calculator can be used to define the highest frequency target a perfect optical system can theoretically resolve. Or it can define the optical system required to resolve a given target frequency. Actual performance may be lower due to optical aberrations or higher due to image enhancement in the camera system.

Learn more about Spatial Resolution.