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FIDO-Φ: A free-falling microstructure imaging profiler


Contents
Functional Description Specifications People
Development Pictures/Movies/Data Cruises Publications
Links

Functional Description
Fido-Φ, or also known as Free-Fall, is a two-dimensional imaging fluorometer. It falls through the water column taking high-resolution images of the physical and planktonic microstructures that exists in our oceans. It's an autonomous, untethered instrument composed of a high sensitivity, low noise, thermo-electric cooled CCD camera (LUMIS) and a green (532 nm) laser. The laser light, spread as a thin sheet, is used to induce the chlorophyll from the microstructures, which lights as fluorescence. The camera is equipped with special filters to image this fluorescence. The imaging takes place 75 cm below the instrument and therefore in a completely undisturbed medium. The fall rate is ~10 cm/s (adjustable) and images are taken at 2-second interval and stored by the camera controller on its internal hard drive. The Field of view (FOV) is 32 by 32 cm with a 312 micron resolution. There is also sensor data that is saved by the sensor controller. Sensor readings include depth, speed, heading, pitch, roll, temperature, and humidity for all 3 housings (camera, laser, and sensor). The sensor controller also controls the laser and the depth at which the weight is released, set to 100 m, allowing the unit to get back to the surface. All data is downloaded via Ethernet once the unit is retrieved and on deck.


General Specifications
The system is broken down into four major components; camera, laser, sensors, and frame. The camera, laser, and sensor components are contained in separate pressure housings. The sensor component consists of a PC with National Instruments interface boards running LabVIEW. The sensor component monitors depth, heading, pitch, roll, and vital statistics of all three housings (temperature and humidity) in addition to controlling an automated weight release system. The camera component is a silightly modified version of the LUMIS system and consists of a PC with Medoptics interface boards and a highly sensitive camera. The laser component consists of a high power diode pumped 532mn laser with a custom lens. The sensor and camera components are connected via ethernet and are both individualy accessable from and external computer.
Detailed Specifications

People
Principal Investigators Jules Jaffe and Peter Franks
Chief Engineer F. Simonet
Mechanical Engineer Fred Ulhman - Hydrodynamic aspects, mechanical design/fabrication.
Software Development Paul Roberts - Data acquisition, instrument control, GUI
David Zawada - Calibration, data analysis/algorithms.
Optical Consultant Karl Moore
Lab Assistants Mathew Diebolt
Consultant Wendy Storms
Graduate Students Erdem Karakoylu, David Zawada

Development Pictures/Movies/Data
To view the movies through the web browser, Quicktime plugin is required. To save the movies to your local machine right-click (Shift-click) the .mov or .avi links.
Pictures

Cruise: 07/05/01

DeepTank Tests
Cruise 07/23/01

Movies
Deployment Off the Sproul

Download:
.mov

 Movie from Cruise: 03/30/01

Download:
.mov
Movie from Cruise: 07/05/01

Download:
.mov

 Movie from Cruise: 07/23/01

Download:
.mov
Movie Demo of Freefall

Download: .mov

Data
Chlorophyll florescence spatial distribution profile in the water column down to 50 meters.
1fps movie Download: .mov
3fps movie Dowalond: .mov
Subsurface chlorophyll maximum layer at 35 m depth. This image is 13x13 cm and shows a strong vertical gradient of the background chlorophyll (cells smaller than about 5 microns), as well as increased numbers of large, intensely fluorescent cells. Such vertical gradients are common in the images
Dinoflagellates at 14 m depth. Note the individual cells.
Diatom chains at 35 m depth in the fluorescence maximum. This image is not smeared - note the variety of orientations of the cells. Our bottle sampling underpredicted the average length of the chains, as they broke being poured from the bottle.
Side-scattered light recorded by the camera with the chlorophyll filter removed. Compare this image with those from above: there are many more particles, and more larger particles than appear in the fluorescence images.
Side-scattered image of particles being mixed by the instrument platform as it heaved up and down when attached to the ship. Notice the small-scale flow stuctures within the image.

Cruises
03/30/01 - Day cruise, off the coast of San Diego, CA.
07/05/01 to 07/06/01 - Free Fall I, off the coast of San Diego, CA.
07/23/01 to 07/27/01 - Free Fall II, off the coast of San Diego, CA.

Publications
Jaffe, J.S. Computer modeling and the design of optimal underwater Imaging Systems. IEEE J. Oceanic Eng. 15(2):101-111. (1990).
Palowitch, A. and Jaffe, J.S.. "Three-dimensional ocean chlorophyll distributions from underwater serial sectioned fluorescence images". [Article] Applied Optics. 33(14):3023-3033, 1994 May.
Palowitch, A. and Jaffe, J.S.. "Optical serial sectioned chlorophyll-a microstructure". [Article] Journal of Geophysical Research. 100(C7):13,267-13,278, 1995.
Jaffe, J.S., P.J.S. Franks and A.W. Leising. Simultaneous imaging of phytoplankton and zooplankton distributions. Oceanography 11(1): 20 pgs. (1998)
Franks, P.J.S. and Jaffe, J.S.. Microscale distributions of phytoplankton: initial results from a two-dimensional imaging fluorometer, OSST. Marine Ecology Progress Series, 220: 59-72, (2001).

Sponsors
National Science Foundation

Links
Peter Franks Web Site