Regularities of Signal and Sensitivity Variation of a Reflection Fiber Optopair Sensor Dependent on the Angle between Axes of Fiber Tips

Regularities of variation of output signal U of one reflection fiber optopair dependent on the distance h between active fiber tips and light reflecting body-mirror (U-h characteristics) and on the angle 2θ between the FAT axes, the distance between FAT being minimal (b = bmin), have been explored by modelling and experimentally. The parameters of U-h characteristics have been established: maximal sensitivity Smax(h), localization and values of maxima and inflection points (+,−) of a function U(h), length of interval ∆h in which the output signal U(h) is linear (98 % of sensitivity maxima), as well as dependences of these parameters on the angle θ and distance h. It has been shown that the experimental results are well described by the formulas improved by the authors previously. It has been demonstrated that reflection fiber optopair sensitivity Smax to displacement considerably increases with an increase of the angle θ. It has been defined that, with an increase of the angle θ up to 20°, sensitivity increases up to 30 times when active fiber tips axes are almost parallel and the diameter of the fiber core is 100 µm, and 125 µm with cladding. Apart from that, Smax increases almost exponentially up to θ = 20°. A drawback of such an RFP is that with an increase of the angle θ, the size of the sensor head also increases. However, due to their considerably increased sensitivity, they can be and are wide used

Some Advanced Fiber-Optical Amplitude Modulated Reflection Displacement and Refractive Index Sensors

Some advanced fiber-optic amplitude modulated reflection displacement sensors and refractive index sensors have been developed. An improved three-fiber displacement sensor has been investigated as a refractive index sensor by computer simulations in a large interval of displacement. Some new regularities have been revealed. A reflection fiber-optic displacement sensor of novel configuration, consisting of double optical-pair fibers with a definite angle between the measuring tips of fibers in the pairs has been proposed, designed, and experimentally investigated to indicate and measure the displacement and refractive index of gas and liquid water solutions. The proposed displacement sensor and refractive index sensor configuration improves the measuring sensitivity in comparison with the known measuring methods. The refractive index sensor sensitivity Snsub = 4 × 10−7 RIU/mV was achieved. The displacement sensor sensitivity is Ssub = 1702 mV/µm in air (n = 1.00027)

Fiber-optic sensors for nanometric displacement and vibration measurement in mechatronics

Fiber-optic sensors are widely used for displacement and vibration measurements in mechatronic systems. Sensors can be of very small size and operate in blast danger conditions and strong electromagnetic interference environment. In this work modeling and experimental investigation of the characteristics U-h of fiber-optic sensor of displacement have been accomplished with a view to obtain the maximal sensitivity in the displacement and vibration measurements. The modeling and experimental results were perfectly coincidental, therefore the limit sensitivity of sensors can be predicted by modeling. Configurations of non-contact fiber optic sensors of the maximal possible sensitivity have been found, the metrological parameters of which do not depend either on the degradation of the light source, intensity or on the elements used in the mechatronics system measurements as well as on the value of the mirror reflection coefficient and changes with the aging process. All that increases the reliability of mechatronics system monitoring, which is of utmost importance for their exploitatio

The fiber-optic non-contact piezomechanical nano-micro positioning, manipulating and measurement system

A non-contact fiber-optical piezomechanical (FOP) nano-micropositioning, manipulating and measuring system has been developed and investigated. The system consists of a non-contact fiber one optopair reflection sensor with a semiconductor light source (light diode), a reflected light receiver with a p-i-n photo diode, an amplifier of electronic signals, and a positioning device, the resolution of which is 0.5 µm. The diameter of the fiber sensor measuring head is 3 mm and its length is 10 mm. The positioning device is fixed in front of a mirror. The diameter of fiber core is 100 µm and the external diameter is 125 µm (WF100/110/125P22). Fiber length may reach up to 200 m. The FOP system also has a piezoceramics positioning and manipulating system with a mirror. The piezoceramics system is fastened to the positioning device. The dependence of the fiber sensor signal U on the distance h to the mirror, located on piezoceramics, has been measured. The obtained U-h characteristic has a peak on two parts of linear dependence of an increasing and decreasing signal. Sensitivity of the U-h linear part in front of the peak is higher and equal to 1.6725 nW/nm, and that of the decreasing signal part is 1.388 nW/nm. These parts can be used for displacement indication and measuremen

The fiber-optic non-contact piezomechanical nano-micro positioning, manipulating and measurement system

A non-contact fiber-optical piezomechanical (FOP) nano-micropositioning, manipulating and measuring system has been developed and investigated. The system consists of a non-contact fiber one optopair reflection sensor with a semiconductor light source (light diode), a reflected light receiver with a p-i-n photo diode, an amplifier of electronic signals, and a positioning device, the resolution of which is 0.5 µm. The diameter of the fiber sensor measuring head is 3 mm and its length is 10 mm. The positioning device is fixed in front of a mirror. The diameter of fiber core is 100 µm and the external diameter is 125 µm (WF100/110/125P22). Fiber length may reach up to 200 m. The FOP system also has a piezoceramics positioning and manipulating system with a mirror. The piezoceramics system is fastened to the positioning device. The dependence of the fiber sensor signal U on the distance h to the mirror, located on piezoceramics, has been measured. The obtained U-h characteristic has a peak on two parts of linear dependence of an increasing and decreasing signal. Sensitivity of the U-h linear part in front of the peak is higher and equal to 1.6725 nW/nm, and that of the decreasing signal part is 1.388 nW/nm. These parts can be used for displacement indication and measuremen

Fiber-optic sensors for nanometric displacement and vibration measurement in mechatronics

Fiber-optic sensors are widely used for displacement and vibration measurements in mechatronic systems. Sensors can be of very small size and operate in blast danger conditions and strong electromagnetic interference environment. In this work modeling and experimental investigation of the characteristics U-h of fiber-optic sensor of displacement have been accomplished with a view to obtain the maximal sensitivity in the displacement and vibration measurements. The modeling and experimental results were perfectly coincidental, therefore the limit sensitivity of sensors can be predicted by modeling. Configurations of non-contact fiber optic sensors of the maximal possible sensitivity have been found, the metrological parameters of which do not depend either on the degradation of the light source, intensity or on the elements used in the mechatronics system measurements as well as on the value of the mirror reflection coefficient and changes with the aging process. All that increases the reliability of mechatronics system monitoring, which is of utmost importance for their exploitatio

Modified Fiber Optic System for Monitoring the Railgun Rail Deflections

The work presents a research into adequacy of two models of an individual fiber optic sensor of a system of identical sensors, which is designed for measuring the railgun rail deflections. The presented models are compared with the data of an experiment. It has been found that a more simple model (in view of the scope of calculation) is more convenient as it concerns the calibration on the grounds of the data of the experiment

Frequency and Sensitivity Limited Fiber-Optic Transducers

Modelling and experimental investigation of U-h characteristics of fiber-optic reflective displacement transducer, with the aim to obtain the maximal sensitivity and high speed in the displacement and vibration measurements, are presented. Excellent agreement between theory and experiment was obtained, therefore the limiting sensitivity of transducers can be predicted by modelling. Configurations of non-contact fiber optical transducers of the maximal possible sensitivity and speed were found, the metrological parameters which do not depend either on the degradation of the light source intensity or on elements used in the measurements, as well as on the value of the mirror reflection coefficient and changes due to aging. All that increases the reliability of measurement system, which is of utmost importance for process monitoring

Šviesos perdavimo modeliavimas šviesolaidinėje atspindžio sistemoje

Light transmission in the reflection fiber system, located in external optical media, has been investigated for application as sensors. The system was simulated by different models, including external cavity parameters such as the distance between light emitting and receiving fibers and mirror positioning distance. The sensitivity to a linear displacement of the sensors was studied as a function of the distance between the tips of the light emitting fiber and the center of the pair reflected light collecting fibers, by positioning a mirror. Physical fundamentals and operating principles of the advanced fiber optical sensors were revealed