…Wherein we learn about our heroes first idea and the origin of the LISST acronym

Time: Sometime in the 1980’s
Where: Somewhere in the North Atlantic (probably)

On board the R/V Oceanus, a scientific party deployed another round of deep-sea instruments, measuring parameters for sediment transport. On board the vessel was a young Dr. Yogi Agrawal, research scientist at Woods Hole Oceanographic Institution (WHOI). By this time Yogi had long established his interest in measuring marine particles with the development of a deep ocean marine snow camera. During the cruise, British scientist Professor Nick McCave brought to Yogi’s attention a paper on a laboratory laser diffraction (LD) instrument. The paper showed internally inconsistent results that needed explanation. This accidental exchange would lead to the introduction of LD into oceanography.

R/V Oceanus

In 1988, Yogi left WHOI and moved to Seattle to continue his Navy funded work at Flow Research, Inc. A young Chuck Pottsmith worked in the laboratory. Yogi retained Chuck to help with his various engineering and research programs. It would become the basis of a partnership that is now 34 years old and counting.

In the late 1980’s, research in sediment transport in the deep-sea shifted focus to coastal and continental shelves. Implementing a field research program on the California shelf, the US Navy’s Geology and Geophysics office invited proposals for a next-generation sediment measurement device. At the time, optical transmissometry and acoustic backscatter were the two methods in use. Inspired by the paper Nick McCave had shown him years earlier, Yogi proposed a laser diffraction device that would measure not only concentration of sediments, but also the size distribution. The idea was selected and funded by then US Navy Program Manager Dr. Joe Kravitz.

Dr. Joe Kravitz

The first LISST instrument was made using a linear CCD array detector. Detectors for laser diffraction instruments require a huge dynamic range. To extend the small dynamic range of an available CCD, a variable density photographic film was placed on the CCD faceplate. The densest part of the film was where the scattered intensity would be highest, and vice versa.

The new instrument needed a name and an acronym. Enamored at the time with the music of Franz Liszt, Yogi and Chuck fitted the closest acronym LISST to the instrument: Laser In-Situ Scattering and Transmissometry. In 2016, while visiting Budapest, the home of Franz Liszt, for Sequoia’s 5th PiE Conference, the partners learned that LISST is indeed pronounced in Hungarian as LISZT would be in English. LISST is a Sequoia Trademark, now used even for non-laser diffraction instruments.

In Part II we will learn what can happen when you go for a walk on Powell Street in San Francisco.