We present a new digital holographic microscope (DHM) with a low coherent source for the quantitative imaging of smooth and optically rough objects. The experimental design of the microscope uses an in-line experimental geometry based on the Fizeau interferometer and shows the depth sectioning capability due to the limited longitudinal coherence of the source. A polarization-phase shifting approach is implemented to extract the quantitative and speckle-free image from the experimentally recorded interference fringes. To test and experimentally demonstrate the working of the proposed DHM, we present the results of the quantitative images for different objects.