In this paper, a Fizeau interferometer with double interference cavity is proposed to solve the influence of the environmental factors in high precision phase measurement. The proposed method adds a reference mirror, combined with a low-coherence source, to construct two interference cavities, which have the synchronous phase change. One of them has an adjustable spatial carrier frequency, which is used to calculate the relative deformation phase during the test, while the other has the same null fringe with the standard Fizeau interferometer. The measured phase can be retrieved by using the least square method with the calculated deformation phase and null fringe patterns. In addition, the visibility of the fringe of the two interference cavities are analyzed. Simulation and experiment demonstrate that the proposed method can realize the dynamic measurement of the mirror under the influence of the time-varying environment, and has reliable measurement accuracy.
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