OPTICAL SYSTEM AND METHOD FOR CHANGING THE LENGTHS OF OPTICAL PATHS AND THE PHASES OF LIGHT BEAMS

摘要

The optical system comprises two optical paths (P1, P2), and an arrangement for changing the length of the two paths including two phase modulators (M1. M2) one coupled to each of the paths. A driving system (Figure 3) applies power to the phase modulators to drive them in the same direction and to change the amount of power applied to the phase modulators in opposite directions so as to change the length of each optical path in a different direction. As a result, the relationship between the changes in the amount of power applied to the modulators and the resulting changes in the phase of light beams passing through the device becomes substantially linear.