Ernst Abbe
Ernst Karl Abbe is a pioneering physicist and has done outstanding contributions to the fields of optics, microscopy, ....
Abbe Diffraction limit d = lambda/(2 n sin(theta))
Airy disk (3D picture/simulation)
Resolution limits
References and Further reading
http://www.rsc.org/chemistryworld/Issues/2008/November/AbbesRefractometer.asp