LISST-25

LISST-25 marks a generational advancement in the measurement of suspended sediments. Unlike all prior sediment sensors, optical or acoustic, the LISST-25 maintains its calibration over a 200:1 range of particle sizes. A comparison of the LISST-25 and a transmissometer can be seen in Application Note L10. It is shown that when evaluated with particles of a broad range of sizes and of several types - manmade spheres or natural terrigenous, or marine sediments from several locations - the LISST-25 held calibration to within a factor of 2 whereas transmissometer calibration changed by 2 orders of magnitude The LISST-25 uses a newly patented concept. It employs a collimated laser beam to illuminate particles, and a specially shaped focal plane detectors behind the receiving lens. A comet shaped detector senses volume concentration of particles, holding calibration over a 200:1 size range. A second detector measures the area concentration. A Sauter Mean Size of sediments is provided from the ratio of these two outputs also. For details, please see Application Note L005 The instrument incorporates a transmissometer function. This output is also made available to compare data with historical records.

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