Lord Rayleigh
By the way Lord Rayleigh is not the same person as Walter Raleigh who according to my distant memories from old encyclopaedias introduced potatoes and smoking to Great Britain, anyway he was a Sir not a Lord. Lord Rayleigh defined the criterion for resolving two point objects. Last week I was playing with Sketchup and thought it might be an interesting exercise to draw a 3D model of the light from two point sources diffracting through a circular opening.I succeeded in making the model but it didn't really help in the understanding of the concept. The part a lot of students find difficult is connecting the angle between the two sources with the angle between the principal max and first min. In the end I settled for 2D using SMART notes to make the drawings that can are then rotated with respect to one another.