Deep Submersible Particle Size Analyzer

LISST-Deep - Sequoia Scientific, Inc.

The LISST-DEEP instrument obtains in-situ
measurements of particle size distribution,
optical transmission, and the optical
volume scattering function (VSF). Using a
red 670nm diode laser and a custom
silicon detector, small-angle scattering
from suspended particles is sensed at 32
specific log-spaced angle ranges. This
measurement is post-processed to obtain
sediment size distribution, volume
concentration, optical transmission, and
VSF. The electronics and optical
configuration in the LISST-DEEP are very
similar to Sequoia’s workhorse, the LISST-
100X. However, because of the extreme
difficulty associated with keeping
alignment under high pressure, the LISSTDEEP
hardware design is radically different
from the LISST-100X. This allows the
LISST-DEEP to be deployed down to 3000
m and obtain reliable measurements of
the in situ particle size distribution and
volume concentration in waters with
optical transmission up to 98.5%.