Multi-sensor system using plastic optical fibers for intrinsically safe level measurements

Abstract

A system for measuring liquid level in multiple tanks using optical fibe technology has been developed. Oil fiel service industry or any sector requiring liquid level measurements in flammabl atmospheres can be benefite from this intrinsically safe technology. The device used a single lens for the emitting and receiving fibe and it is based on amplitude variations as a function of the liquid distance and not in time of fligh or phase detection. Being the firs fiber-opti liquid level sensor with those characteristics for long ranges (>200 cm). A simple model to describe their behavior has been derived and tested on two prototypes. A Monte-Carlo method is used to fi the experimental data and obtain the model parameters. High accuracy between experimental data and fitte curve is obtained. The prototypes have a good linearity, better than 1.5% FS (full scale). Sensor heads are made of plastic optical fiber (POF) that are easy to handle, fl xible and economical. They are excited by 650 nm lasers, housed in ST-connectors to obtain compact and rough prototypes. Optical multiplexing is used to increase the measuring safety area. Frequency division multiplexing is used to address each sensor head. A discussion about the influenc of tilts and aberrations is also included.

Advanced multifunctional optical switch for multimode optical fiber networks

“…Therefore, the number of applications that use POF is quickly increasing. POF is being used in video transmission in medical equipment, or in multimedia applications for civil aviation and high range cars [1], in-home [2] and access networks, wireless LAN backbone or office LAN and intrinsic optical sensor networks [3] among others.…”

A wireless fluid-level measurement technique

“…The density of 2 κ is far greater than that of 1 κ and 1 2 κ κ >> . The capacitance, ) (z C , is dependent upon the dielectric interface level, z , and is the summed capacitance due to contributions from both dielectric substances.…”

“…Fiber optic methods are inherently safe and can be used in combustible liquids because the light propagated through the fiber is modulated to correspond with a liquid level instead of modulating electical voltage [2][3][4][5][6]. The fibers themselves are not susceptible to electromagnetic interference.…”

Reconfigurable optical multiplexer based on liquid crystals for polymer optical fiber networks

“…In addition, these fibers are lightweight, immune against electromagnetic interferences (EMI) and of easy installation. Therefore, POF is being used in video transmission in medical equipment, or in multimedia applications for civil aviation and high range cars [3], or in optical sensor networks [4,5], where due to its safety nature, they are made of inert materials and can be used in flammable atmospheres where no risk of explosion is caused even under malfunction operation.…”