This lecture discusses the optimization of the intensity ratio between incoming and outgoing light when circular polarized light passes through a quarter-wave plate and a polarizer. By considering the rotation of the electric field axis and the orientation of the quarter-wave plate and polarizer, the instructor explains how to achieve the maximal intensity ratio by choosing the appropriate angle theta. The process involves analyzing the transformation of circular polarized light to linear polarized light after the quarter-wave plate and determining the optimal angle theta for maximum intensity transmission through the polarizer.