Simultaneous bright field and quantitative phase imaging of living cells in flow with a fiber optic digital holographic off-axis Mach-Zehnder interferometer approach

We present an approach for simultaneous bright field (BF) and laser-based quantitative phase imaging (QPI) in which a fiber optic digital holographic off-axis Mach-Zehnder interferometer setup with a single digital camera sensor is applied. Recording of grayscale multiplexed images enables high-speed multimodal BF and QPI imaging that is only limited by the frame rate of the acquisition sensor. BF and QPI images are recovered from the recorded multiplexed images by Fourier filtering in combination with weighted image subtraction. The performance of our approach and its application in imaging flow cytometry are demonstrated by experimental results from the system characterization and the analysis of tumor cells within a microfluidic chip with hydrodynamic focusing capabilities.