Partial division type interference device and measuring method

The invention discloses a partial division type interference device and a measuring method. The partial-splitting interference device comprises a reference light path for transmitting reference light, the reference light comprising light of a first frequency transmitted on a fast axis and light of a second frequency transmitted on a slow axis, a signal light path for outputting the reference light to an interferometer comprising a polarization rotator on the signal light path, the polarization rotator is used for rotating the polarization state of the light so as to rotate the light transmitted on a fast axis to a slow axis for transmission and rotate the light transmitted on the slow axis to the fast axis for transmission, so that light of a second frequency transmitted on the fast axis and light of a first frequency transmitted on the slow axis are obtained, and the interferometer outputs signal light; and the first detector is used for receiving interference light signals of the reference light and the sig