Diffraction Limit and Dispersive Media

This lecture discusses the diffraction limit of optical systems, explaining how objects smaller than a certain size cannot be resolved. It also covers the behavior of electromagnetic waves in dispersive media, such as how an optical microscope cannot distinguish between objects smaller than 400nm. The lecture delves into the concepts of evanescent waves and Lorentz materials, detailing how certain materials exhibit multiple resonances. Additionally, it explores the properties of dipole moments in materials and the plasma frequency in metals. The instructor emphasizes the limitations imposed by the diffraction limit and the characteristics of various materials when interacting with electromagnetic waves.