| dc.description.abstract | The backscattering coefficient bb is one of the inherent optical properties of natural
waters which means that it is independent of the ambient light field in the water.
As such, it plays a central role in many problems of optical oceanography and is used
in the characterization of natural waters. Essentially, any measurement that involves
sending a beam of light into water must account for all inherent backscattering. Some
of the applications that rely on the precise knowledge of the backscattering coefficient
include studies of suspended particle distributions, optical bathymetry, and remote
sensing. Many sources contribute to the backscattering, among them any suspended
particles, air bubbles, and the water molecules themselves. Due to the importance of
precise measurements and the ease with which water samples can be contaminated,
an instrument to determine directly and quickly the backscattering coefficient in situ
is highly desirable.
We present such an instrument in both theory and experiment. We explain the
theory behind our instrument and based on measurements made in the laboratory
we demonstrate that our prototype shows the predicted behavior. We present data
for increased extinction in the water, and show how measuring the extinction and
taking it into account improves the quality of our measurements. We present calibration
data obtained from three different particle sizes representing differently shaped
volume scattering functions. Based on these measurements we demonstrate that our
prototype has the necessary resolution to measure the backscattering coefficient bb over the whole range found in natural waters. We discuss potential improvements
that should be made for a commercial version of the instrument. | en |
