An optical fibre sensor for particle concentration measurement in water systems based on inter-fibre light coupling between polymer optical fibres

Zhang, Fenghong; Lewis, Elfed; Scully, Patricia

doi:10.1177/014233120002200506

Cited by 12 publications

(4 citation statements)

References 8 publications

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“…where P 0 is the output power obtained without any absorbent surrounding the sensing region that is the bent/unclad portion, ␥ i are the molar evanescent wave absorption coefficients 22 of different modal groups in a multimode fiber having different penetration depths, C is the concentration of the absorbing species, l is the length of the sensing region, and P(l), is the power output in the presence of an absorbent. The conventionally used expression for evanescent wave spectroscopy is 23…”

Section: Theory Of Operationmentioning

confidence: 99%

Microbent optical fibers as evanescent wave sensors

et al. 2002

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Microbent optical fibers are potential candidates for evanescent wave sensing. We investigate the behavior of a permanently microbent fiber optic sensor when it is immersed in an absorbing medium. Two distinct detection schemes, namely, bright-field and dark-field detection configuration, are employed for the measurements. The optical power propagating through the sensor is found to vary in a logarithmic fashion with the concentration of the absorbing species in the surrounding medium. We observe that the sensitivity of the setup is dependent on the bending amplitude and length of the microbend region for the brightfield detection scheme, while it is relatively independent of both for the dark-field detection configuration. This feature can be exploited in compact sensor designs where reduction of the sensing region length is possible without sacrificing sensitivity. © 2002 Society of Photo-Optical Instrumentation Engineers.

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Section: Theory Of Operationmentioning

confidence: 99%

Microbent optical fibers as evanescent wave sensors

et al. 2002

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“…The detection of bacteria and other living cells has been demonstrated using POF taper sensors [9]. Another example from this field is the measurement of the particle concentration in water systems based on the light coupling between two POFs to determine the water quality [10]. …”

Section: Introductionmentioning

confidence: 99%

Optical Strain Measurement with Step-Index Polymer Optical Fiber Based on the Phase Measurement of an Intensity-Modulated Signal

Becker

Ziemann

Engelbrecht

et al. 2018

Sensors

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Polymer optical fibers (POFs) have been proposed for optical strain sensors due to their large elastic strain range compared to glass optical fibers (GOFs). The phase response of a single-mode polymer optical fiber (SM-POF) is well-known in the literature, and depends on the physical deformation of the fiber as well as the impact on the refractive index of the core. In this paper, we investigate the impact of strain on a step-index polymer optical fiber (SI-POF). In particular, we discuss the responsivity of an optical strain sensor which is based on the phase measurement of an intensity-modulated signal. In comparison to the phase response of an SM-POF, we must take additional influences into account. Firstly, the SI-POF is a multi-mode fiber (MMF). Consequently, we not only consider the strain dependence of the refractive index, but also its dependency on the propagation angle θz. Second, we investigate the phase of an intensity-modulated signal. The development of this modulation phase along the fiber is influenced by modal dispersion, scattering, and attenuation. The modulation phase therefore has no linear dependency on the length of the fiber, even in the unstrained state. For the proper consideration of these effects, we rely on a novel model for step-index multi-mode fibers (SI-MMFs). We expand the model to consider the strain-induced effects, simulate the strain responsivity of the sensor, and compare it to experimental results. This led to the conclusion that the scattering behavior of a SI-POF is strain-dependent, which was further proven by measuring the far field at the end of a SI-POF under different strain conditions.

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“…Moreover, in many industrial applications or in academic research, it is not only mono-dispersed suspensions needing to be measured but also poly-dispersed suspensions. Most of the light scattering techniques have been applied to mono-dispersed systems [17][18][19] . Others that have been applied to poly-dispersed systems determine only particle size distributions but not concentration directly [20][21] .…”

Section: Introductionmentioning

confidence: 99%

High concentration measurement of mixed particle suspensions using simple multi-angle light scattering system

Buaprathoom

Pedley

Prins

et al. 2012

Optical Sensing and Detection II

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A simple multiple-angle light scattering system was developed for the differential measurement of particle concentrations in suspension even in high concentration where multiple scattering effects are significant based on size. The system combines multiple-angle detection to collect scattered angle dependent light intensities, and Partial Least Square Regression method (PLS-R) to compose the predictive models for analyzing scattered signal obtain concentrations of samples under investigation. The system was designed to be simple, portable and inexpensive. It employs a diode lasers (red AlGaInP-based) as a light source and a silicon photodiode as a detector and optical components, all of which are readily available. The technique was validated using 1.1 μm and 3.0μm polystyrene latex beads in both mono-dispersed and poly-dispersed suspensions. The measurement results showed good agreement between the measured results and reference values. Their deviations from the reference values are 2.4% and 1.5% relating to references' concentrations of 8 10 3 .

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An optical fibre sensor for particle concentration measurement in water systems based on inter-fibre light coupling between polymer optical fibres

Cited by 12 publications

References 8 publications

Microbent optical fibers as evanescent wave sensors

Microbent optical fibers as evanescent wave sensors

Optical Strain Measurement with Step-Index Polymer Optical Fiber Based on the Phase Measurement of an Intensity-Modulated Signal

High concentration measurement of mixed particle suspensions using simple multi-angle light scattering system

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