Patent ID: 8861982

Claim:
An interferometer, comprising: a light splitter configured to split a measured light into a first split light and a second split light; a unit configured to multiplex the first split light and the second split light, to generate a first interference light and a second interference light; a first optical phase modulation unit configured to adjust a phase difference between the first split light and the second split light; a second optical phase modulation unit configured to adjust a phase difference between the first split light and the second split light; a controller configured to drive one or both of the first optical phase modulation unit and the second optical phase modulation unit, according to whether an optical system, including the interferometer, is in a system activation mode or in a normal operation mode; wherein when the optical system is in a system activation mode, the controller drives the first optical phase modulation unit; wherein when the optical system is in a normal operation mode, the controller drives the second optical phase modulation unit but does not drive the first optical phase modulation unit; and wherein the first optical phase modulation unit is configured to operate faster in modulation speed than the second optical phase modulation unit.