A New Digital Holographic Microscope for the Study of Biological Systems

New instrumentation and bioimaging devices are required for viewing key metabolic processes in living organisms among microbial communities in plant environments. Small footprint devices are needed to make in situ, nondestructive, functional, and quantitative measurement independent of large, expensive instruments. These must also be affordable, deployable, and accessible to the larger scientific community. An affordable, low footprint digital holographic microscope will be built to satisfy the stated measurement requirement by exploiting unique features of holography, to remove key limitations in existing bioimaging systems and enable imaging and measuring key metabolic processes within and among microbial cells and multicellular plant tissues. Digital holograms can now be recorded on small, lightweight sensor arrays at video rates, processed in real time, and offer the many advantages associated with digital media, transferring much of the overall optical process into electronics and software. A hologram records all optical information in a light wave scattered from, transmitted through, or reflected from a biological surface of interest, enabling dynamic, microscopic imaging over large fields of view and depths of field with a relatively small instrument, capabilities that cannot be achieved with conventional imaging devices. Phase I demonstrated, experimentally and theoretically, the capability of digital holographic microscopy to record and measure typical critical parameters of biological cells, their movements, and changes in time, employing a flexible and controllable simulated biological system to refine, qualify, and characterize the measurement system and identify critical issues. Phase II will include constructing a refined portable digital holographic system and software initiated during Phase I and research on live biological samples and rhizosphere problems with a team consisting of microbiologists that are actively involved in this field. The system potential in biological research will be demonstrated and compared with conventional imaging tools. Digital holographic microscopy should have significant applications in industrial processes and biological research, where speed is at a particularly high premium. As an example, the semiconductor industry is a particularly attractive target. The proposed system differs from available systems and provides a flexible mix of spatial resolution, angular resolution, throughput, field of view, penetration depth and phase sensitivity by taking digital microscopy to a new level. Software developed in this research can be adapted to existing commercial systems providing many enhancements to such systems.