Fiber-optic liquid-level sensor

Raatikainen, Pekka; Kassamakov, Ivan; Kakanakov, Roumen; Luukkala, M.

doi:10.1016/s0924-4247(96)01396-9

Cited by 95 publications

(48 citation statements)

References 3 publications

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“…In the fields where the liquid level monitoring of several specific points is needed or liquids of different refractive index (RI) are required to be differentiated, many discrete or multipoint liquid level sensors are proposed [6][7][8][9][10]. Compared to their electronic counterparts, optical fiber sensors show good potential in explosive environment due to their nonconductive measurements and electromagnetic immunity [11], broadening the application area.…”

Section: Introductionmentioning

confidence: 99%

A Multipoint Liquid Level Sensor Based on Two Twisted Polymer Optical Fibers in a Race-Track Helical Structure

et al. 2018

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A multipoint liquid level sensor based on the RI modulation of macrobend polymer optical fiber (POF) couplers is proposed. By twinning two twisted POFs around a race-track column, a series of U-shaped sensing heads are achieved. The output power in the passive fiber declines in a step form while the sensing heads are immersed into liquid in turn. The introduction of UV optical cement in the gap between two POFs improves the side-coupling ratio, increasing the attenuation per step. For the measurement range of 100 cm, the resolution is 2 cm. The sensor can differentiate different liquids with low temperature dependence.

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Section: Introductionmentioning

confidence: 99%

A Multipoint Liquid Level Sensor Based on Two Twisted Polymer Optical Fibers in a Race-Track Helical Structure

et al. 2018

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“…A variety of techniques have been developed for liquid level sensing, involving methods that are mechanical [1], electrical [2], acoustic [3], or ultrasonic [4], and optical methods [5][6][7][8][9][10][11][12][13][14][15][16]. Among them, electrical liquid level sensors are widely used in practice.…”

Section: Introductionmentioning

confidence: 99%

Cryogenic fluid level sensors multiplexed by frequency-shifted interferometry

Chen

Xü

et al. 2010

Appl. Opt.

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We present a liquid level sensing system for cryogenic fluids based on an array of aluminum-coated fiber Bragg gratings written in high-attenuation fibers (HAFs) interrogated by frequency-shifted interferometry (FSI). The sensors are heated up optically through the absorption of light at the core of the HAF sections. The distinct thermal response of sensors in the liquid from that in the gas provides an unambiguous means to detect the liquid level. FSI allows the sensors to have overlapped spectral response, and, therefore, has the potential of accommodating a larger number of sensors in the array. The measurement of liquid nitrogen level using this system was experimentally demonstrated. The successful combination of aluminum-coated HAF Bragg grating sensors and the FSI technique promises a viable solution for liquid level sensor networks at cryogenic temperatures.

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“…Different configurations have been proposed for discrete optical level sensors such as, exposed fiber gratings [1], and special fiber tips which rely on intensity variations as the liquid level makes contact with the sensing region [2,5]. In the case of special fiber tips they operate on frustrated total internal reflection in fibers which could be obtained through angled or retroreflecting tips [2], conical/tapered tips [3], special fiber tip design [4], or the attachment of reflecting elements as prisms [5]. In all cases the need to have a special fiber tip requires either very special fiber treatment or the attachment of an external component, which increases the sensor complexity and cost.…”

Section: Introductionmentioning

confidence: 99%

Novel multimode interference liquid level sensors

et al. 2010

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A novel all-fiber Multimode Interference (MMI) liquid level sensor is proposed and demonstrated. We show that MMI effects can be effectively applied for multiplexed liquid level sensing, and by selecting an adequate fiber, discrete and continuous level sensing is feasible. Using a standard 105/125 multimode fiber a simple discrete level sensor was fabricated, which can also can also discriminate the refractive index of the liquid. When a specialty fiber, know as NoCore fiber is used, both continuous and discrete level sensing can be achieved. We can also modify at will the continuous level range by increasing the No-core fiber by the appropriate length, while retaining the ability to determine the refractive index of the liquid during the level measurement. The MMI liquid level sensors are not only inexpensive, but their fabrication is quite simple.

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Fiber-optic liquid-level sensor

Cited by 95 publications

References 3 publications

A Multipoint Liquid Level Sensor Based on Two Twisted Polymer Optical Fibers in a Race-Track Helical Structure

A Multipoint Liquid Level Sensor Based on Two Twisted Polymer Optical Fibers in a Race-Track Helical Structure

Cryogenic fluid level sensors multiplexed by frequency-shifted interferometry

Novel multimode interference liquid level sensors

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