In this chapter we present three types of microscopy-related configurations while the first one is used for 3-D
of the inspected samples, the second one is used for
3-D imaging, and the last one presents an overview digital holographic microscopy applications. The first configuration is based on temporal tracking of secondary reflected
when imaged by properly defocused optics. We validate the proposed scheme by using it to monitor 3-D spontaneous contraction of rat’s cardiac muscle cells while allowing nanometric tracking accuracy without interferometric recording. The second configuration includes projection of temporally varying speckle
patterns on top of the sample and by proper decoding exceeding the diffraction as well as the geometrical-related lateral resolution limitation. In the final part of the chapter, we overview applications of digital holographic microscopy (DHM) for real-time non-invasive 3-D sensing, tracking, and recognition of living microorganisms such as single- or multiple-cell organisms and bacteria.