## 1 Introduction  
Biological specimens are often highly transparent and differ only slightly from their environment in terms of light permeability. This renders them hard to image via standard light microscopy techniques and necessitates the use of phase-imaging methods to obtain information about their morphology. While phase-contrast microscopy techniques allows the phase information to be observed, it does not give the quantitative measurements that is critical for cell research [1]. Interferometric techniques such as the digital holographic microscopy (DHM) method are the most promising methods of observation in this regard. They allow for the accurate quantitative measurement of cell morphology [2], a highly adaptive focusing methodology [3], and they hold potential for imaging deep inside living tissues [4, 5]. Imaging of cell cultures is an indispensable part of cell research and is one of the primary application areas of the digital holographic microscopy method. In recent studies, two-dimensional cell culturing methodology is being replaced by the three-dimensional (3D) dynamic cell culture methodology which presents a more similar environment to the human body for the cells in the culture [6]. 3D visualization via the DHM methodology may have some problems to deal with because of the scattering nature of the tissue and noises introduced by the medium flow in the fluidic chips. Morphological analysis of cells in vitro has been studied widely before. An early study by [PERSON] et al. used a discrete Fresnel transformation for the automatic parameter selection for a DHM method which was used for high-resolution living cell analysis [7]. [PERSON] et al. used a time domain optical coherence approach for the assessment of the flow velocity of red blood cells [8]. A following study by [PERSON] et al. used the Rayleigh-Sommerfeld backpropagation method for the identification of the shape of a given cell [9]. A more recent study by [PERSON] et al. used telecentric DHM to obtain quantitative phase maps of MDA-MB-231 cells to assess their motility characteristics [10]. Similar studies that investigate cellular processes based on DHM methodology can be found in the literature [11; 12; 13]. However these studies use polystyrene beads in their experiments and there is no medium that interfered with the light. The presence of a cellular medium creates significantly more complex scattering patterns and renders the backpropagation of the scattered light harder [14]. However, in real-life applications, cell cultures are almost always examined in cellular mediums which requires the proposed methodologies to be robust to these noises. To the best of our knowledge, there exists no study that investigates and compares different noise reduction methodologies for eliminating interferometric noises in cellular mediums. A recent study by [PERSON] et al. is based on a singular value decomposition (SVM) classifier on the phase features of cancer cells to score and classify cells according to their morphologies [15]. They used a Mach-Zehnder-based optical method to obtain the height maps of epithelial (Gie-No3B11) and fibroblast (human gingival) cell lines, as well as MDA-MB-231 and MCF-7 breast cancer cell lines. They used linear SVMs as binary classifiers of the non-cancerous cells that graded the cancer cells by transfer learning. The resulting classifier was able to classify epithelial and mesenchymal cells with about a 96% accuracy. In this study, we propose an interferometric measurement method for the observation of the epithelial-mesenchymal transition process. A phase-stepping Mach-Zehnder-based optical setup is employed to obtain a reconstruction of the phase information inside a dynamic cell culture. To this end, we use a high frequency piezo actuator and a coupled high speed complementary metal oxide semiconductor (CMOS) camera sensor. The piezo motor is used for phase stepping and the integrated CMOS sensor captures the interferogram synchronously with the motion of the actuator.