New apparatus for the teaching of optics

Using discrete light rays — or ‘ray streaks’ as they are now called — to help in the teaching of the elementary principles of optics is not new. The apparatus shown in FIGURE 1 bears a close resemblance to that developed by F. Meier in the 'thirties. However, the use of such apparatus has been largely neglected or limited to demonstration work, and the usual ray‐box suffers from the disadvantage of producing, by means of a lens, a virtual source.