Publication Date:
2022-05-25
Description:
Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 52 (2005): 2376-2389, doi:10.1016/j.dsr.2005.09.002.
Description:
The field of ocean geochemistry has recently been expanded to include in
situ laser Raman spectroscopic measurements in the deep ocean. While this
technique has proved to be successful for transparent targets, such as fluids and
gases, difficulty exists in using deep submergence vehicle manipulators to
position and control the very small laser spot with respect to opaque samples of
interest, such as many rocks, minerals, bacterial mats, and seafloor gas hydrates.
We have developed, tested, and successfully deployed by remotely operated
vehicle (ROV) a precision underwater positioner (PUP) which provides the
stability and precision movement required to perform spectroscopic
measurements using the Deep Ocean In Situ Spectrometer (DORISS) instrument
on opaque targets in the deep ocean for geochemical research. The positioner is
also adaptable to other sensors, such as electrodes, which require precise control
and positioning on the seafloor. PUP is capable of translating the DORISS
optical head with a precision of 0.1 mm in three dimensions over a range of at
least 15 cm, at depths up to 4000 m, and under the normal range of oceanic
conditions (T, P, current velocity). The positioner is controlled, and spectra are
obtained, in real time via Ethernet by scientists aboard the surface vessel. This
capability has allowed us to acquire high quality Raman spectra of targets such
as rocks, shells, and gas hydrates on the seafloor, including the ability to scan
the laser spot across a rock surface in sub-millimeter increments to identify the
constituent mineral grains. These developments have greatly enhanced the
ability to obtain in situ Raman spectra on the seafloor from an enormous range
of specimens.
Description:
Funding was provided by a grant to MBARI from the David and Lucile Packard
Foundation.
Keywords:
Optical instruments
;
Underwater vehicles
;
Oceanographic equipment
;
Raman spectroscopy
;
Motion control
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
2892390 bytes
Format:
application/pdf
Permalink
