USGS Patent Pending for a New Underwater Microscope System
The U.S. Geological Survey has a patent pending for a new underwater microscope system. Developed
by Hank Chezar and David Rubin, the new system digitally collects and analyzes electronic images
of sediment grains on a riverbed or seabed. Using the new system, scientists can collect hundreds
of electronic samples and later analyze them for grain size in a matter of hours to days, a
process that typically takes months using traditional methods of sampling and grain-size analysis.
The new system not only saves time but also spares scientists from sampling activities that can be
dangerous in areas with strong currents.
Sand grains: Sample image of
sand grains on the bed of the Colorado River. Image was taken in highly turbid water and is
approximately 1 cm across. The ring of light spots near the outside of the image is a reflection
from LED (light-emitting diode) lights built into the video camera assembly.
The heart of the system is a close-up microscope lens installed on a modified version of a
commercially available camera. The camera is at the bottom of a cylinder encased in a steel ball.
To "sample" the bottom, the ball is lowered to the seabed or riverbed while the camera shoots
continuous video footage. Operators monitor video images sent in real time to the surface vessel.
The ball is settled on the bottom until sand grains are pushed right up against the window in the
bottom of the ball, and the scene on the video monitor is still.
The 'Eyeball:' Video camera assembly (a.k.a. "Flying Eyeball"),
including stabilizer fin, camera pressure case, and bridle.
The system acquires a video image of the bottom at 1/4-inch distance from the focal plane of the
lens, and sends the video signal through a cable to a digital video-recording console on the surface
vessel. The special housing that encases the underwater microscope camera--together with ballasting,
winching and operational procedures--permits topside operators to work from a small vessel even in
swift-moving river environments. Digital video sequences recorded on the surface vessel are later
viewed on a computer, and the most sharply focused frames of each bottom-contact sample are saved.
These images are then analyzed electronically for grain size using software developed by David Rubin.
Topside: Video console,
including video monitor and digital recorder.
The system is designed to assist sedimentologists, marine geologists, and other scientists interested
in studying surficial sediments in lakes, rivers, and oceans. First deployed on the Colorado River in
Grand Canyon, the system has also been used off Oahu, Hawaii, and Santa Cruz, California.
Improvements to the system's lens design are in development. These improvements will permit gravel
characterizations, which have aquaculture and fish wildlife applications.
In the photo at right, University of Hawai`i graduate student Eric Grossman annotates video footage from the underwater
microscope during fieldwork directed by Bruce Richmond. Here the system is being used to videotape
bioclastic grains off Waikiki on the south shore of Oahu, Hawai`i. Physical samples of the sediment
were also taken and will be sieved to determine grain size. Grain-size data derived from sieving will
be compared to grain-size data derived from digital analysis of the video images to assess the system's
usefulness for analyzing angular, bioclastic grains such as those found off Oahu.
annotates video footage from the underwater microscope.
in this issue:
Great Blue Hole of Belize
Channel Islands Cruise
Lake Mead Mapping
New Underwater Microscope System
Reston Open House
Monterey Open House
Acadiana Migratory Bird Day
Global Assessment of Geologically-Sourced Methane
GIS 2001: Logan
GIS 2001: Massachusetts Bay
Northeast Earthquake Hazards Map
June Publications List