Field-portable digital holographic quantitative phase imaging with a compact microscope's add-on module

Digital holographic microscopy (DHM) is emerged as a promising quantitative phase-contrast imaging tool for full complex wavefront reconstruction of micron-sized bio-samples. The technique covers the dynamics investigation ranging in scales from sub-cellular to tissue and from milliseconds to hours. Recent advances of DHM lie in the configuration and numerical development of the method and making it more feasible for the users without optical expertise. In this paper, we aim to propose a low-cost and portable add-on module for DHM, which can be mounted on either the ocular or camera port of a conventional microscope and easily turn it to a multi-modal bright-field and DHM imaging tool. The module works based on the off-axis, common-path geometry using a single Fresnel biprism in the detection path of the microscope. This configuration enables a compact and cost-effective solution for point of care applications and in field measurements. The feasibility and efficiency of the device have been confirmed through several morphological investigations on biological specimens and the sub-nanometer phase stability enables the measurement of cell dynamics and phenotypic changes such as motility, growth, differentiation and membrane oscillations.