Lecture
This lecture covers the transformation of diverging spherical electromagnetic waves into converging ones using lenses. It explains the properties of Gaussian waves, focal waist, divergence, and peak intensity. The instructor discusses the focusing of far thermal or fluorescent sources, the computation of image intensity, and the expected intensity after focalization. Additionally, the lecture explores the focusing of collimated beams, Gaussian beams, and TEMnm modes. It concludes with a discussion on beam quality and selective laser sintering and melting.