This tutorial explains the human eye, its function, and performance limits from the perspective of an experienced optical engineer and lens designer. Concise and readable, with examples and data. Intended for students, practicing engineers, and technology users.Contents - Preface - Introduction - The Eye - Magnification and Vision - The Magnifier - Design - The Eyepiece - Design - The Microscope - Design - The Telescope - Design - The Borescope - Design - The Periscope - Design - Biocular - Design - Review and Summary of Design Concepts - References - Index