“Staying in Focus” — An Online Optics Tutorial on the Eye

The human eye and its vision problems are often used as an entry subject and attention grabber in the teaching of geometrical optics.¹ While this is a real‐life application students can relate to, it is difficult to visualize how the eye forms images by studying the still pictures and drawings in a textbook. How to draw a principal ray diagram or how to calculate the image distance from a given object distance and focal length might be clear to most students after studying the book, but even then they often lack an understanding of the “big picture.” Where is the image of a very far away object located? How come we can see both far away and close‐by objects focused (although not simultaneously)? Computer animations,² popular with our computer‐game savvy students, provide considerably more information than the still images, especially if they allow the user to manipulate parameters and to observe the outcome of a “virtual” experiment. However, as stand‐alone learning tools, they often don't provide the students with the necessary physics background or instruction on how to use them.