This lecture covers Fresnel diffraction, focusing on the calculation of contributions from Fresnel zones using polar coordinates. It explains how each zone contributes to the total field at a point, the concept of Fresnel lens, and the effects of different shapes of openings on diffraction patterns. The lecture also delves into the Fraunhofer diffraction of slits and holes, the Babinet principle, and the resolution of optical microscopes. Additionally, it explores the near-field microscope principle and the use of SNOM/NSOM for imaging molecules.