Using in-situ holographic microscopy for ocean particle characterization

Optical scattering in all but the clearest natural waters is dominated by the local particle dynamics. The link between the suspended particle field and the bulk scattering properties of natural waters is poorly known because adequate technology is lacking to fully characterize all the parameters of the particle field required to compute the bulk optical properties (especially for ephemeral bubbles and aggregates). Holography provides non-intrusive, non-destructive, high-resolution 3-D imaging of particles (including bubbles) in their natural environment at a resolution and sample volume size that no other instrument can currently achieve. The ability to optically section holograms (image planes) during reconstruction allows the extraction of all individual particle characteristics (at the same lateral resolution), their 3-D spatial distribution, and motion (in short pulsed serial holograms). As part of a USA NOPP project to commercialize an in-situ Digital Holographic Microscope (DHM), field data with a prototype in-situ DHM and several bench-top DHMs were collected in East Sound, WA, USA; an environment that had both zooplankton and phytoplankton thin layers and notable particle dynamics. Preliminary results from this study and a project overview will be presented.