Quantitative phase imaging comparison of digital holographic microscopy and transport of intensity equation phase through simultaneous measurements of live cells

Quantitative phase imaging (QPI) of live cells allows label-free assessment of cell morphology and quantitative estimation of cell thickness, and therefore volume. Of the techniques available for QPI, digital holographic microscopy (DHM) is an accurate and reliable high-resolution phase imaging technique, but assembly and operation of a DHM capable setup can require significant optical engineering experience and specialized equipment that may not be practical for many labs. Transport of intensity equation (TIE) imaging is a QPI method that is compatible with conventional bright field microscopy, has a lower implementation cost without the need for specialized optics or alignment, and has significantly reduced spatial and temporal coherence requirements when compared to DHM. However, TIE is susceptible to different forms of noise than DHM and its accuracy in live cell imaging has not been well studied. Here, we present a microscope capable of performing simultaneous DHM and TIE phase reconstructions to compare both methods and validate TIE as an accurate phase retrieval method both for a static sample array and for live cells.