Sequoia LISST-100X, Руководство пользователя

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4 LISST-100X User’s Guide
General Description
The LISST-100X instrument is a laser diffraction device. It consists
of optics for producing a collimated laser beam, a specially
constructed detector array, electronics for signal pre-amplification
and processing, data storage and scheduling computer, and a
battery system.
The instrument is capable of autonomous operation. Windows
software (XP and W7 32- and 64-bit compatible) is provided to
program the instrument for a specific sampling schedule. The
primary measurements delivered by the LISST-100X are the small-
angle scattering properties of particles in water, the laser optical
transmission, depth, and temperature. An auxiliary Analog port is
available for recording data from an external device such as an
OBS 3+, a Sea-Bird MicroCat CTD or a Turner Designs Cyclops-7
fluorometer
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.
After recovery of the instrument, small-angle scattering data are
off-loaded from the instrument and subsequently
inverted
mathematically on a PC to produce the particle size distribution.
The inversion function is included in the Windows software. For
MATLAB users, inversion scripts are available for download from
Sequoia’s website:
www.SequoiaSci.com .
The principal measurement—angular scattering distribution— is
obtained over 32 ring-detectors whose radii increase logarithmically
from 102 to 20,000 microns. The detector is placed in the focal
plane of the receiving lens. The rings cover an angular range from
0.0017 to 0.34 radians (Type B) or 0.00085-0.17 radians (Type C).
This angular range corresponds, respectively, to size ranges from
1.25 to 250 µm (Type B) or 2.5 to 500 µm (Type C).
See Appendix B: Size Ranges, Observation Angles, Data Storage
Format on page 101 for more information.
General layout
The LISST-100X consists of the following parts: a solid-state diode
laser operating at 670 nm wavelength and fiber-optically connected
to a laser beam collimating system, a beam manipulation and
orienting system, a scattered-light receiving lens, the custom
designed 32-ring detector, preamplifier electronics, a ring-selecting
multiplexer circuitry, and a data logger. All these components are
inside the black-anodized pressure housing and the user has no
access to any of these.
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The LISST-100X must be configured for one of these options at the factory prior to shipping.