Optical backscatter sensors

Instrumented tripods with flowmeters, transmissiometers, optical backscatter sensors (OBS), in situ settling cylinders, and programmable camera systems have often been used in marine environments, for example, oceanographic studies of flow conditions and suspended particle movements in the bottom nepheloid layer [37,38]. These instruments were deployed to study suspended-sediment dynamics in the benthic boundary layer and were able to collect small water samples (1-2 L) at given distances from the seafloor. An instrumented tripod system (Bioprobe), which collects water samples and time-series data on physical and geological parameters within the benthic layer in the deep sea at a maximum depth of 4000 m, has been described [39]. For biogeochemical studies, four water samples of 15 L each can be collected between 5 and 60 cm above the seafloor. Bioprobe contains three thermistor flowmeters, three temperature sensors, a transmissiometer, a compass with current direction indicator, and a bottom camera system. 

Roger, A.J. Shatahn, S.V. and Kanellopoulos, S.E. Distributed Measurement of Flow Pressure via Optical-fibre Backscatter Polarimetry. 17th Int. Conf. on Optical Fibre Sensors (OFS-17), Bruges, Belgium, SPIEI-VoL 5855 (2005), pp. 230-233... 

Platinum and palladium porphyrins in silicon rubber resins are typical oxygen sensors and carriers, respectively. An analysis of the characteristics of these types of polymer films to sense oxygen is given in Ref. 34. For the sake of simplicity the luminescence decay of most phosphorescence sensors may be fitted to a double exponential function. The first component gives the excited state lifetime of the sensor phosphorescence while the second component, with a zero lifetime, yields the excitation backscatter seen by the detector. The excitation backscatter is usually about three orders of magnitude more intense in small optical fibers (100 than the sensor luminescence. The use of interference filters reduce the excitation substantially but does not eliminate it. The sine and cosine Fourier transforms of/(f) yield the following results ... 

Optical-Sensing-Based Flow Sensors Backscatter interferometry, optical coherent tomography, and particle-imaging velocimetry are some of the optical techniques for flow sensing. The backscatter interferometric flow-sensing system [3] may be crmsideied to be in this category. This system is based on synchronous... 

Light waves that transmit through an optical fiber are scattered by nonlinear interactions with acoustic waves with some of the backscattered signals returning to the input end— this phenomenon is called the BriUouin Scattering. The BriUouin scattered light is associated with the BriUouin Frequency Shift (BFS) vjf,lj. It has been found that there is a linear relationship between vfe,T) and the strain and temperature T in the fiber optic sensor (Bao et al. 1995, Kurashima et al. 1993), which can be expressed as ... 

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