U.S. Geological Survey Open-File Report 2007-1194

Figure 22A.  Two D&A Optical Backscatter Sensors (OBS).

Figure 22A. Two D&A Optical backscatter sensors (OBSs). The OBS emits a beam of infrared light that is scattered by suspended sediments in the water column. Suspended sediment concentration is derived by combining the quantity of light reflected back to the sensor with sensor calibration coefficients. (Photograph courtesy of D&A Instruments.)