Liquid-level sensor with optical fibers

“…In liquid-level measurement, sensors are usually divided in devices for continuous measurement [3] and for point measurement [4]. Both can be non-intrusive, that is, they do not touch the liquid, or intrusive, that is, they are dipped into the liquid.…”

Section: Introductionmentioning

confidence: 99%

All-plastic optical-fiber level sensor

Bottacini

Burani

Foroni

et al. 2005

Microw. Opt. Technol. Lett.

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“…This latter solution poses another problem because the light can undergo undesired reflections or refractions which can distort the measurements. Others used SMFs of reduced aperture [19] for short distances, being simply intrusive schemes [20], intrusive large arrays of individual fluid-sensitive transducers [21] or fibers with clad and unclad zones [22]. In other systems, the measurement is non-intrusive and it is based on the light reflection on the surface of the liquid [23].…”

Section: Introductionmentioning

confidence: 99%

Intensity-Based Optical Systems for Fluid Level Detection

Vázquez

Montero²

2012

EEENG

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Abstract:In this work different patented optical sensing solutions are reviewed, mostly for their application of measuring fluid level within tanks, containers or bio-mass boilers in condominiums, thus providing an intrinsically safe sensing sce-nario within harsh and hazardous environments, due to the passive nature of light. In general, the intensity modulation of the light is very attractive since it is simple in concept, reliable, and can produce optical sensors which offer a wide range of applications at lower costs, thus facilitating their final commercialization and market spread. The optical sensing solu-tions discussed in this work include a fiber-optic sensor for fluid detection/level with intrinsic self-referencing property thus solving one of the main drawbacks when using intensity-based sensors, namely the undesirable and unexpected opti-cal power fluctuations when operating. Moreover, a low-cost intensity-based POF sensor for fuel level measurements in paramotoring and powered paragliding is presented. It features a very simple and a very low-cost solution for these sports, attending the increasing demand of new and more sophisticated embedded sensors in the flight instrumental. Going on from this, a fiber-optic fluid level sensor for a range greater than 2m is described. The system uses a single lens and a sin-gle fiber but being possible to increase the measuring safety area by optical multiplexing. Finally, a fluid level sensor based on a Light Dependent Resistor (LDR), which includes a temperature control scheme, is presented. Its final embodi-ment design is also shown and described.

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“…Different laser and optical instrumentation devices have been already used in level measurement systems, as the level gauge described in [2] and the references included in this patent; but in any of them the laser, so the electronic driver, is in the sensor head. Optical fiber have been used in the sensor heads for measuring very short distances, in the micrometer range with a high precision, using fiber-opti long period gratings as in [3], for measuring tens * + + of centimeters employing: continuous flui sensing fiber [4][5][6], or intrusive large arrays of individual fluid-sensit ve transducers [7]. Another works on liquid level sensors reported intrusive digital transducers with a range of several meters using fiber with clad and unclad zones [8] or liquid-coupling waveguides [9], microbending optical-fibe sensors with hysteresis for indirectly measuring up to 2.5 m [10] and transducers for point measurements in control level devices [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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

Vázquez

Gonzalo

Vargas

et al. 2004

Sensors and Actuators A: Physical

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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.

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Liquid-level sensor with optical fibers

Cited by 65 publications

References 2 publications

All-plastic optical-fiber level sensor

All-plastic optical-fiber level sensor

Intensity-Based Optical Systems for Fluid Level Detection

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

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