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Discover the Sequoia range

Submersible and Field Instruments for Measuring Particles and their Properties.

Sequoia Scientific has been building instruments for making measurements in the marine environment since 1995.

LISST – Holo

The LISST-Holo from Sequoia is the world’s first commercially available submersible Digital Holographic Particle Imaging System. The system was developed by Dr. Alex Nimmo Smith at the Marine Institute of the University of Plymouth (UK) and Sequoia holds a world-wide license for manufacture.

LISST – Tau High-Precision Transmissometer

LISST-Tau is a high-precision transmissometer for underwater vehicles, profiling packages, CTDs, and other systems. With high-quality optics and a carefully selected LED source, it transmits a collimated beam through the water, and precisely measures the light transmitted through its 15 cm path. Light modulation with synchronous detection rejects ambient light, while oversampling and averaging yield better than 16-bit resolution. LISST-Tau’s digital controller applies calibration coefficients, corrects for temperature effects, and transmits data from both digital and analog outputs.

LISST – Black

The LISST-BLACK has been developed for oil spill applications and is a self-contained stand-alone instrument for use on profiling packages, towed and remote vehicle applications, for deployment during and after an oil spill event.

LISST – 200X

The LISST-200X marks a major advance in the technology of submersible particle size and concentrations measurements. Smaller, lighter, smarter, for starters, this model combines the size ranges of the original LISST-100XB and -100XC. It stores all instrument files on-board; no more searching.

LISST – Portable

The LISST-Portable|XR is the world’s first and only battery powered portable particle size analyzer. It can be used in the field, in the laboratory or on the factory floor.

LISST – Deep

The LISST-Deep instrument obtains in-situ measurements of particle size distribution, optical transmission, and the optical volume scattering function(VSF) at depths down to 3,000 meters.


The LISST-STX is a submersible field instrument developed for in-situ observation of the size-dependent settling velocity distribution of suspended particles. It incorporates a mechanized Settling Column.


The LISST-VSF from Sequoia is the world’s first commercially available submersible instrument for measuring the volume scattering function (VSF) of water in situ with some polarization discrimination capability. The LISST-VSF covers the angular range from 0.094 to 150 degrees.

LISST – Stokes

The LISST-STOKES from Sequoia is the world’s first commercially available submersible instrument for measuring the depolarization ratio in situ.

LISST – Horizon

The LISST-Horizon is a self-contained instrument for bench-top deployment in a research vessel laboratory. Plumbed to continuous underway uncontaminated seawater, it continuously measures PSD and particle concentration, as well as inherent optical properties (IOPs) beam attenuation (c) and volume scattering function (VSF, β) at 520 nm. From these IOPs, scattering (b), backscattering (bb), backscattering ratio (bb/b), and by difference, absorption (a = c – b), can be derived.

LISST – ABS acoustic backscatter sensor

Sequoia Scientific, Inc. is proud to offer the first low-cost acoustic backscatter sensor designed specifically for measuring suspended sediments. This is a new type of sediment sensor, superior to optical backscatter sensors (OBS) for 4 reasons.


FlowControl-Sub is a microprocessor-controlled fully submersible 3-way valve system for use in flow-through applications on profiling platforms such as for example CTD’s or profiling floats.

Sequoia – accessories

A range of accessories for Sequoia instruments, including deployment cages, batteries, flow tubes, mixing chambers, anti-fouling bio-blocks, cables, test chambers, custom optical paths, custom enclosures, etc.

Need more information? If you would like to speak to us, we are available.