Sequoia Scientific


Flow-Through Automated Particle Size and Scattering Measurement

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 particle size distribution, concentration, and inherent optical properties.

A first prototype has been delivered to NASA (see our News release). Sequoia is taking orders for the LISST-Horizon.

For further information, contact us!


  • Automated deployment in flow-through seawater systems, including clean water backgrounds, cleaning, and scattering standard measurement
  • Mixers in the sample chamber to keep particles suspended during measurement
  • Automated filtered sample background using attached external particle filter (0.2 μm)
  • Measures near-forward (0.1-15°, 36 log-spaced detectors) and side scattering (35-150°, 24 detectors) from a 520 nm laser source
  • Beam attenuation and particle sizing from proven LISST-200X optics, with extended pathlength for application to offshore waters
  • Side scattering allows for particle sizing over an extended range, ~0.2 to 500 μm
  • Raw data stored internally and offloaded via ethernet for processing with provided MATLAB software


Parameters Measured

  • Volume scattering function (VSF) from 0.1 to 150°
  • Particle size distribution inverted from scattering measurements
  • Beam transmission
  • Derived IOPs including total scattering, backscattering, and absorption by difference (a = c – b)
  • Sample temperature and fluidics parameters such as pressures and flow rate

Mechanical and Electrical

  • Dimensions: L = 67.4 cm x W = 37.5 cm x H = 29.3 cm
  • Weight: 19 kg
  • Laser: 520 nm solid state diode laser
  • External power input: 110/220 VAC converted to 24 VDC using provided power brick
  • Plumbing connections using 3/8 inch OD (1/2 inch for drain) tubing and push-to-connect fittings
  • External tanks for holding clean water for background, cleaning solution, and scattering standard; each with pressure sensor for monitoring tank level