Driven to diffraction
This one is the diffraction of light by a circular aperture. I have to admit that there aren't so many occasions in the course where we really need to show things in 3D but occasionally its useful. This one is the first stage in preparing a 3D image of the Rayleigh criterion. I find that students often find it difficult to realise that the angle to the first minima is the same as the angle between the two objects. Maybe 3D will help and even if it doesn't I will have added another dimension to the lesson.