Quantitative phase imaging camera with a weak diffuser based on the transport of intensity equation

We present an efficient quantitative phase imaging camera with a weak diffuser (QPICWD) based on the transport of intensity equation (TIE). The compact QPICWD measures object induced phase delay under low-coherence quasi-monochromatic illumination via examining the deformation of the speckle intensity pattern. Analysing the speckle deformation with an ensemble average of the geometric flow, we can achieve the high-resolution distortion field by the TIE. We present some applications for the proposed design involving nondestructive optical testing of microlens array with nanometric thickness and imaging of fixed and live unstained HeLa cells. Since the designed QPICWD needs no modification of the common bright-field microscope or additional accessories, it may advance QPI as a widely useful tool for biological analysis at subcellular levels.