Demonstration of a dual-mode digital-holographic/light-field-fluorescence microscope for extant life searches

A promising way to search for microbial life in our solar system's Ocean Worlds is to make use of 3-d microscopes, as these can provide single-image inventories of the complete contents of liquid sample volumes. Two applicable 3d microscopy techniques are digital holographic microscopy and light-field fluorescence microscopy. The former can provide high-resolution imaging information on cellular morphology, structure, index of refraction, and motility, while the latter can identify and locate targeted molecule families, such as lipids and nucleic acids. The combination of this pair of 3-d techniques thus provides a powerful suite of diagnostic tools. We have recently combined both types of microscope into an integrated dual-mode microscope prototype aimed at demonstrating its utility at terrestrial field sites, and the combined instrument has already been taken on an initial foray into the field to assess its performance and shortcomings. Here we describe the design and capabilities of our dual-mode microscope, as well as initial performance measurements obtained during its first field trip to the local seashore.