"Version: 20240701"--Title page verso.Includes bibliographical references.1. Introduction -- 1.1. Historical background -- 1.2. Some recent advances -- 1.3. Motivations -- 1.4. Features and potential advantages of metalenses2. Basics of metalens optics -- 2.1. Optics of metasurfaces -- 2.2. Metalens phase profile -- 2.3. Relationship with the classical lens -- 2.4. Meta-atoms -- 2.5. Lens equat…