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LISST Instruments
Commercial instruments for particle intelligence (particle sizing, concentration, imagery and optical properties) based on laser diffraction
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Submersible Laser-Diffraction based Particle Size Analyzer
LISST-200X
The LISST-200X is a submersible laser-diffraction based particle size analyzer designed to measure particle size and concentration in rivers, streams, ports, harbors, coasts and oceans, whether for biological, sediment transport, or environmental monitoring needs. Smaller, lighter, smarter, for starters, the LISST-200X combines the features of the original LISST-100X with new improvements to make a major advance in the technology of submersible particle size and concentrations measurements.
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Portable Particle Size Analyzer
LISST-Portable|XR
Truly portable – completely self-contained with built-in data logger, processor, rechargeable battery, and 7” color touch screen display.Particle Size Range 0.35 to 500 micronsPumped and recirculating mixing chamber that keeps large and heavy particles suspended.Shock mounted optics block that can withstand the rigors of field use.A built-in ultrasonic probe for complete sample dispersion.Touch panel allows for easy SOP programming, sample analysis and display of data without a PC.Multiple Mie models as well as Fraunhofer model available for inversion, selectable from the touch panelAll data-processing is performed on board and stored in ASCII format. No post-processing necessary.Outputs: Total volume concentration, mean size, standard deviation, optical transmission, D5, D10, D16, D25, D50 (median grain size), D60, D75, D84, D90, D95, D60/D10 (Hazen uniformity coefficient), particle surface area, silt fraction, silt volume, size distribution, battery voltage, sample notes.Based on the laser diffraction principle. Compliant with ISO-13320-1 standard.
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Acoustic Backscatter Sensor
LISST-ABS
The LISST-ABS is a fixed-point monitoring sensor. It uses a new and novel technique to internally compensate for geometric beam spreading and attenuation, yielding de-attenuated backscatter signal strength. It is held pointing into flow for low drag.
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Deep Submersible Particle Size Analyzer
LISST-Deep
The LISST-DEEP instrument obtains in-situmeasurements of particle size distribution,optical transmission, and the opticalvolume scattering function (VSF). Using ared 670nm diode laser and a customsilicon detector, small-angle scatteringfrom suspended particles is sensed at 32specific log-spaced angle ranges. Thismeasurement is post-processed to obtainsediment size distribution, volumeconcentration, optical transmission, andVSF. The electronics and opticalconfiguration in the LISST-DEEP are verysimilar to Sequoia’s workhorse, the LISST-100X. However, because of the extremedifficulty associated with keepingalignment under high pressure, the LISSTDEEPhardware design is radically differentfrom the LISST-100X. This allows theLISST-DEEP to be deployed down to 3000m and obtain reliable measurements ofthe in situ particle size distribution andvolume concentration in waters withoptical transmission up to 98.5%.
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Optical VSF Sensors
The optical Volume Scattering Function(VSF) is an ‘inherent optical property’ of water that is used by optical oceanographers to predict light propagation, image degradation, remote sensed ocean color, biological environment etc. in water.
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Multi-angle Polarized Light Scattering Measurements
LISST-VSF
In-situ measurements of P 11, P12 and P22 elements of scattering Mueller matrix, (P11 is VSF) from 15-150º.VSF (P11) only at small angles, 0.05 to 10º in 32 logarithmic steps in angles.Only two detectors employed with absolute radiant sensitivity (A/W) calibration.Beam attenuation measured with optics similar to our LISST-100X.Roving Eyeball™ optics permit 1-degree resolution in angles between 15 -150º.Sampling rate at 3 seconds per measurement set (involves 3 turns of Roving Eyeball with unpolarized, vertical, and horizontal polarized laser).Daylight rejection by laser modulation.Dynamic range in VSF measurements extended via laser power modulation.Data from small and large angles in a single data stream, including depth and temperature.
