An unbalanced fiber optic Michelson interferometer as an optical pick-off

摘要

A system (10) for measuring changes in an environmental parameter, such as velocity or pressure, includes an optical signal source (11, 12, 13) for providing a pulsed, coherent light signal, and an interferometer having first and second optical legs (33, 35) of unequal optical path lengths. The signal is split into first and second beams that are respectively directed into the first and second optical legs of the interferometer. A fixed mirror (41) reflects the first beam received at the end of the first optical leg (33) . An optical pick-off (51) includes a movable mirror, positioned to reflect the second beam received from the end of the second optical leg (35). The movable mirror is movable in response to changes in the value of the parameter to be measured. An optical coupler (38) combines the first and second beams after they have been reflected back into their respective optical legs, producing an interference signal, which is detected by an optical detector (39). The detector (39) generates an electronic signal having a value indicative of the value of the interference signal. The electronic signal is analyzed to correlate its value to changes in the value of the environmental parameter to be measured. IMAGE