Our digital in-line holographic microscopes made by 4Deep, obtain 3-D information from particles from laser light, imaging a broad range of plankton and other microorganisms at micrometer resolution. A laser is directed onto a pinhole of a diameter of the order of a wavelength, which acts as the point source from which a spherical wave light emanates. The wave illuminates the objects in its path and forms a diffraction pattern on a CCD chip about a centimeter away. Images are later reconstructed from raw hologram using a Matlab-based processing pipeline.
autonomous underwater glider
Our lab uses an autonomous SLOCUM glider made by Teledyne-Webb Research that allows for sustained observation of ocean properties over wide areas (Davis et al. , 2008 ; Rudnick , 2016 ).
Gliders can operate in all weather conditions, remaining underwater for long periods, with occasional surfacing
intervals to allow communication and data transfer. Our glider is equipped with instruments to measure basic ocean hydrographic properties (e.g. temperature, salinity, and dissolved oxygen and nitrate to dephs of 200m.
A Wirewalker is an autonomous vertical profiler made by DelMarOcean. It uses wave power to ratchet down a vertical wire, with no electronic components and only a few moving parts. At the lower terminus of the profiling range, the cam that rectifies vertical wave motion is released and the package ascends freely and smoothly (Pinkel et al. 2011). Positive buoyancy offsetting the weight of the sensors and batteries is achieved through deep-rated syntactic foam. Our lab generally equips the Wirewalker with a CTD, chlorophyll and CDOM fluorometers, optical backscattering, beam attenuation meter, PAR and dissolved oxygen sensors.
Minions are simple floats in development in our lab, that combine recent technological advancements in environmental tag technology, low-cost imaging and single board computers. Our goal is to make possible dense distributions of sensor-laden Lagrangian (water-following) instruments that will be acoustically tracked as they drift within the ocean twilight zone. These low-cost robots will be able to directly observe the transport and transformation of individual particles that drive the biological carbon pump.
sediment trap timelapse cameras (GelCams)
The GelCam is an upward-facing camera mounted below a transparent plate, with the camera’s focal plane fixed near the upper face of this surface. The housing mounts below a cylindrical particle-intercepting trap containing a polyacrylamide gel layer. When sinking particles land in the gel, they are preserved in the anoxic gel, and are held in place. The camera with LED illumination ring, snaps pictures at a specified interval to track the accumulation and sometimes identity of particles in the trap. for example, basic morphometrics (size, shape, circularity, etc.) and an optical “porosity” using fractal indices, have been useful in classifying various types of marine snow particles (S. Gallager, pers. comm.), including Red-Green-blue (RGB) information that is very informative of particle type (Bishop et al. 2016).