Microscope, Telescope, Interferometer 37
ence in the path of the two pencils is not too great, and provided that the two pencils are reunited at a sufficiently small angle. By altering these conditions of reflection or
38 Light Waves and Theib Uses
refraction we may obtain a very considerable number of variations of form, as illustrated in Figs. 34, 35.
One of these types, enlarged in Fig. 36, has been arranged