Figure 4

Figure 4: Schematic diagram of the unequal-arm Michelson interferometer. The beam shown corresponds to the term 2 2 (D2 - 1)(D 1- 1)f(t) in X(t) which is first sent around arm 1 followed by arm 2. The second beam (not shown) is first sent around arm 2 and then through arm 1. The difference in these two beams constitutes X(t).