Special Forms of the Ray-Transfer Matrix. Consider the following situations in which one of the four elements of the ray-transfer matrix vanishes:
(a) Show that if A = 0, all rays that enter the system at the same angle leave at the same position, so that parallel rays in the input are focused to a single point at the output.
(b) What are the special features of each of the systems for which B = 0, C = 0, or D = 0?