title: A Mach-Zender digital holographic microscope with sub-micrometer resolution for imaging and tracking of marine micro-organisms.
abstract: Digital holographic microscopy is an ideal tool for investigation of microbial motility. However, most designs do not exhibit sufficient spatial resolution for imaging bacteria. In this study we present an off-axis Mach-Zehnder design of a holographic microscope with spatial resolution of better than 800 nm and the ability to resolve bacterial samples at varying densities over a 380 μm × 380 μm × 600 μm three-dimensional field of view. Larger organisms, such as protozoa, can be resolved in detail, including cilia and flagella. The instrument design and performance are presented, including images and tracks of bacterial and protozoal mixed samples and pure cultures of six selected species. Organisms as small as 1 μm (bacterial spores) and as large as 60 μm (Paramecium bursaria) may be resolved and tracked without changes in the instrument configuration. Finally, we present a dilution series investigating the maximum cell density that can be imaged, a type of analysis that has not been presented in previous holographic microscopy studies.
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91009, USA.
authors.forename: Jonas
authors.initials: J
authors.lastname: Kühn
authors.affiliation: Department of Biomedical Engineering, McGill University, 3775 University St., Montreal, Quebec H3A 2B4, Canada.
authors.forename: Bimochan
authors.initials: B
authors.lastname: Niraula
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91009, USA.
authors.forename: Kurt
authors.initials: K
authors.lastname: Liewer
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91009, USA.
authors.forename: J
authors.initials: J
authors.lastname: Kent Wallace
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91009, USA.
authors.forename: Eugene
authors.initials: E
authors.lastname: Serabyn
authors.affiliation: Division of Aerospace Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA.
authors.forename: Emilio
authors.initials: E
authors.lastname: Graff
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, California 91009, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Lindensmith
authors.affiliation: Department of Biomedical Engineering, McGill University, 3775 University St., Montreal, Quebec H3A 2B4, Canada.
authors.forename: Jay L
authors.initials: JL
authors.lastname: Nadeau
mesh_terms: D001419:Bacteria; D004867:Equipment Design; D006696:Holography / Q000295:instrumentation* / Q000379:methods; D008853:Microscopy / Q000295:instrumentation* / Q000379:methods; D010247:Paramecium; D013171:Spores, Bacterial; D014867:Water
chemical_list: D014867:Water