In this article, a new interferometer which accuracy does not depend on the accuracy of the reference is proposed. This interferometer calculates the surface profile of the measured mirror surface using two steps. At the first step, the interferometer obtains the data concerning the reference and a polarized beam splitter (PBS). The interferometer works as a Mach-Zehnder interferometer. At the second step, since the polarized beam splitter is rotated 90 degree, the measured mirror is lightened by a laser beam. In this step, the interferometer obtains the data concerning the reference, the PBS and the measured mirror. Therefore, the difference between these two results corresponds to the surface profile of the measured mirror and it does not include the data of the reference and the PBS. The principle and the experimental results were described.