…Wherein we’ll learn about the LISST-25 and the LISST-Wing

(Part V can be found here: https://www.sequoiasci.com/article/the-history-of-sequoia-part-v/ )

In the late 1990’s, Yogi participated in several FISP (Federal Interagency Sedimentation Project) technical committee meetings upon invitation from USGS sedimentologist Dr. John R Gray. Dr. Gray, USGS and FISP were interested in the LISST technology for measuring suspended sediment concentrations in the US rivers. One of the first outcomes of participating in the FISP meetings was to initiate development of the LISST-25 in the early 2000’s.

The name of the instrument originated from Dr. Gray’s desire to have an instrument one fourth the capabilities and one fourth the price of the original LISST-100. The LISST-25 delivered the total concentration and a mean (Sauter) size. Developing the mathematics behind the LISST-25 further, a subsequent derivative, LISST-25X was invented. It split the total sediment concentration into two: washload (i.e., particles smaller than 62 microns) and total load. The market did not take to this invention, preferring the full capability of the LISST-100 (later the LISST-100X), and both the LISST-25 and LISST-25X were discontinued.

The Original LISST-25 Poster

Around 2003, seeing an opportunity in atmospheric cloud physics, Sequoia developed a LISST instrument for mounting under the wing of research aircraft. Development of this instrument, the LISST-Wing, was funded by the US Navy office of Atmospheric sciences. Only one of these instruments was built and tested. Upon the first in situ test, mounted under an aircraft wing on a plane flying through high altitude clouds, it was realized that the windows froze over, rendering the measurements useless. The project and the instrument idea were abandoned, and the prototype was given to a company active in atmospheric sciences.

LISST-Wing optics cut-away showing laser (left) and ring detector (right)

LISST-Wing seen from the front

Also, on January 1st, 2003, Sequoia opened for business in its current location on 2700 Richards Road Ste 107, Bellevue WA. The December 2002 Christmas break was used to move the entire office into the new location. Shipments, production, and customer support was thus not affected by the move at all.

Our 2700 Richards Road location – home to Sequoia since 2003

In Part VII we’ll learn about the LISST-Infinite, LISST-StreamSide , LISST-SL and LISST-Portable.