The birefringence of common types of optical fibers monotonically depends on temperature and pressure. Birefringence of some types of the side-hole (SH) optical fiber change sign of pressure sensitivity with change of pressure and temperature. This paper theoretically describes these phenomena. It is a supplement to previously described method of calculation of pressure and temperature sensitivity of SH optical fiber.
Theoretical and experimental results of studies on a stability of slow-speed motion generated by different type rotating platforms designed for an investigation of angular velocity meters are presented. An application of fiber optic gyroscope with sensitivity 0.2 deg/h and drift range of Earth rotation give possibility for measurement real rotation generated by platforms in their all work range. Especially, a possibility of a measurement in the lowest range is a new possibility. The method presented in paper has given also a possibility to investigate error sources of generated rotation velocity.
The construction and experimental results of fiber optic sensor using the ring-wedge photodetector is presented. As sensor head the sample of quasi-monomode optical fiber is used. Changes of intermodal interference condition, due to external perturbation, generated changes of output speckle pattern. This pattern differences are automatically recognized by neural processing. The pattern for neural processing is generated by suitable placed ring-wedge photodetector system.
Side-polished single-mode optic fiber has been studied. The effect of fiber parameters and light polarization on a conversion of refractive index changes into phase, differential or intensity signal for liquids is described. For an intensity range the experimental results are also presented.
Stress sensors dedicated for Weigh-in-Motion of road vehicles should exhibit high dynamic range, good accuracy and repeatability, as well as long service life. One of the most promising group of sensors for this application are polarimetric sensors, due to their simplicity and high sensitivity. Preliminary measurements of the optical fiber properties in this application resulted in significant hysteresis being observed even for relatively low stress, which is probably caused by the cladding properties or by the construction of the modulator used in the measurement.
The widespread migration to the Wavelength Division Multiplexing telecommunication systems stimulates the demand for tunable external cavity semiconductor lasers used for production testing and maintenance purposes. As these lasers have a coherence length of hundreds meters and their prices are continually decreasing, it can be predicted that these lasers will soon be commonly used as a source in interferometric and polarimetric sensors. In this paper we present the theoretical description of a distribution optical fiber sensor using polarization mode coupling in a polarization maintaining optical fiber. The performance of the sensor using a tunable semiconductor laser is analyzed and the possible applications of this type of sensor are discussed.
The work presents a method for extraction of a thin regularized contour enabling simultaneous processing of the scene images made in various spectral ranges. The method presented can be easily accomplished in the form of a cellular neural network. The basis of the method is the energy function of states of original images, fitted images, and the contour created, which are defined adequately. Optimization of the fitted images and the contour extracted is made with the gradient decrease method in relation to their states. The energy of the states of images is represented as a sum of a few terms corresponding to various effects of the method. The energy of states subjected to the minimization process determines the architecture and dynamics of the neural network.
In the paper a setup for the measurement of instant velocity of samples subjected to breaking test is described. It was estimated that the maximum speed of deformation is 50 m/s and maximum strain is 5 mm. An optical method has been selected and a measurement setup was built. We discuss the setup performance and the measurement results.
The hitherto obtained results of the research concerning some non-stationary phenomena observed during the radiation emission by the semiconductor laser are presented in the paper. It mainly concerns the damped oscillations of the output signal from laser, as well as the delay of the output laser impulse in relation to the current controlling the working laser diode. The delay time values for a given frequency interval of the signal controlling the laser diode at work were experimentally determined. Using the method of linear regression, an analytical equation was modeled, which connected the delay of the laser impulse t0 in relation to the polarizing current IB. Using the least square method, the values of the above mentioned equation ratios were determined. The phenomena presented in the paper are relevant for the processing reliability of the laser diode in the examined section of a measuring track.
Microzone laser recrystallization is represented as a method for obtaining the SOI structures with improved characteristics. The processes of poly-Si-heating is analyzed theoretically and experimentally. A special attention is paid to the control of processes of defects formation and application of polysilicon layers with increased average grain size in the technology of optoelectronic sensors.
The interdigital piezoelectric transducers are used in the microsize membrane silicon sensors to the generation and detection of the ultrasonic wave. The wave generation and propagation depend on some external factors, and as a result the wave amplitude as well as the phase velocity of the propagation change. The system of the membrane sensor with ultrasonic wave Lambda type can be examined as a delay line. The application of the membrane sensors as a delay line which works in the generator close loop was presented. The equivalent circuit of the generator with the sensor was analyzed by means of the SPICE program.
The construction of the microsensor with the ultrasonic wave Lambda-type as well as the conditions of the wave propagation were presented. The possibilities of the fabrication of multi-layer membranes on the silicon base using the microelectronics technologies were presented and discussed. The analysis of the usefulness of the processes mentioned to the production of the thin membrane sensors was carried out taking the intrinsic stresses into consideration. The summary of the experimental results was done and the most useful parameters of the membrane ultrasonic sensors were pointed out.
This paper presents some problems concerned with SAW NO2 sensors employing copper phthalocyanine (PcCu) as the chemical interface and 128 degree(s)YX lithium niobate as a substrate. The influence of SAW delay lines construction, substrate properties, structure of PcCu coating on the sensor response stability has been studied.
Chemical concentrations such as gas partial pressures may be determined by making use of the class of recently developed solids with fast ion transport. For the detection of many species it is required to modify the surface. Chemical concentrations are directly converted into electrical signals which may be readily further processed for actors or simply for display. The sensors may be based on potentiometric and amperometric principles depending on the specific type of application. Appropriately selected materials allow to eliminate problems of interference by other chemical species. The development of suitable materials has to include also the reference electrodes and housing.
Fluorescent sensor for 3d divalent metal ions have been designed by means of a supramolecular approach: a 2,2'- bipyridine group (the signalling and simultaneously receptor subunit) linked to either a cyclic aza-3n-crown-n group (the anchor). Occurrence of the metal-receptor interaction is signalled through the quenching of bipyridine fluorescence. When the receptor is able to promote a photoinduced energy- transfermechanism, quenching take place. Metal ions can be distinguished (e.g. CuII from other transition metal ions).
The paper is focused on lipophilic acyclic thioethers as neutral ionophores for heavy-metals cations. Membranes based on plasticized PVC containing these carriers exhibited high selectivity toward silver cations over transition metal ions (log KAgM < -4.5) except mercury ions. Membrane containing the ionophore II (with l-naphtyl pendant group) was used to design silver-selective ISE which shows linear response in the range 3 - 6 pAg with a slope of 51.5 mV/pAg. The addition of the pH chromoionophore to the membrane composition allowed to obtain a silver-sensitive optrode membrane, responding in the concentration range 0.01 - 1 mM Ag+.
Thin layers of Ce-Zr-O2-x with varied chemical and phase composition were deposited by magnetron sputtering with pulse power supply system. The phase transition in the function of temperature and additionally during hydrogen treatment were studied. The variation of resistivity of such layers was found during changing of the gas atmosphere. By comparison, the properties of thin films prepared by sol-gel method were also studied.
Thermal and electric faults developing inside transformers lead to the generation of gaseous products dissolving in the insulating oil. Chromatographic analysis of the gas products composition and concentration (DGA) is a routine procedure used in test and maintenance of the transformers. Unfortunately DGA is rather a laboratory method and cannot be applied in the field during the transformers exploitation. The research aimed at working out a portable system for fast, introductory DGA analysis by means of semiconductor gas sensors. DGA procedures, test system construction and efficient gas extraction methods as well as the results of various oil sample tests are discussed. Unexpected impact of the extraction method on the sensor response is also mentioned.
The authors developed fuzzy logic procedure for the exact estimation of ozone concentration in air with variable humidity. The used sensor array consisted of thin film ozone sensor fabricated by the authors and commercial Keithley humidity sensor. Two-input fuzzy sensor model was elaborated using the known calibration data and developing the learning procedure based on genetic algorithms. The performance of the model was tested.
The simple electrochemical cell Au (NASICON) Au which is sensitive to NO2 and SO2 atmosphere due to voltage excitation was investigated. The shape of current/voltage characteristic is strongly dependent on specific gas concentration and reveal specific peaks. Selection of sweep polarization of the sensor is very important.
The basic element of electrochemical SO2/SO3 sensors based on superionic conductors is the quality of applied material and its crystallographic structure. This paper presents structural analysis of different solid state electrolytes fabricated on the basis of Ag2SO4. It was doped with different sulfates. The structures of synthesized materials with different concentrations of sulfates are compared. Ionic conductivity strongly depends on composition of electrolyte and its crystallographic structure. X ray investigations were performed with diffractometer made by Philips using CuK(alpha ) radiation. The influence of dopants on the composition of solid solution of synthesized superionic conductors and on the change of microstructure Ag2SO4 was observed and discussed.
Fluorescence techniques, due to very precise light detecting methods, has become one of the basic analytical tools. Luminescent reactions or light emitting organisms are the natural base for large growing area of biosensors. However for weak fluorescence measurements photomultiplier tubes are usually used for the detection of light. Employing a Liquid Core Waveguide, it is possible to set up a small and easy to handle system for measurements of weak fluorescence intensity with a photodiode as a light detector.
An optical system for measuring the spectrum of the complex refractive index of liquids in the UV-NIR range is described. The presented optical fiber measurement method allows remote control of the index. The developed refractometer has been tested with samples from different sections of paper mill and chemical pulp mill production processes. The obtained accuracy of the real part refractive index measurements was 10-5 with resolution 2 (DOT) 10-6 (for the wavelength in range 300 - 920 nm with spectral resolution better than 0.5 nm). The absorption corresponding to the imaginary part of the refractive index is measured in 0 divided by 20 dB/cm range with 0.01 dB/cm resolution.
The modification of salinity sensor was achieved in such a way that it is possible to perform salinity measurement and directly to send the data about an exceeding of salinity level for the purpose of quick intervention permitted by National Environmental Standards. The designed system of a network of central controllable sensors may be useful to automatic monitoring of an environment.
In the paper the results of temperature investigations of polymer humidity sensor based on polyethyleneimine is presented. Sensor was prepared by chemical modification of polyethyleneimine and vacuum sputtering of gold electrodes on thick polymer film. The high thickness of the film limit the dynamic properties of the sensor. Electrical properties of the sensor were examined by impedance spectroscopy. The results allow structure optimization and improvement of dynamic properties of the sensor.
The paper presents an idea of using of multilayer heating systems for shaping of temperature fields distribution. The presented results of investigations and simulations have been realized on the models of gas sensors heaters made in two versions: single circuit and sensor arrays. The effects of the number of resistors, their geometry as well as arrangement in the system on the temperature distribution have been analyzed. For studies the specialized computer program HYBTERM has been used.
When constructing ozone sensor one should consider dynamics of circuit inputs and of circuit itself. That dynamics is related to heat capacity conductivity of sensors substrate and case. Physical parameters are described as an implicit functions but we can use simplified model to resolve input space. During measurement stochastic parameters like humidity, medium temperature, medium flow velocity should be observed, due to their influence on heat conductivity and convection. When PID controller with two state output was used to stabilize temperature, regardless of constant input parameters at system output appeared binary noise. That phenomenon is related to temperature sensitivity of semiconductor layer which is higher than sensitivity of PID controller. That sensitivity causes amplification of controller output signal changes. Solution of that problem are physical models based estimators.
When constructing micro- and milirobots, it is important to secure that structural elements perform also metrological functions. Silicon is used in microrobots, while for milirobots polymer composite materials are applied. These composites shall have the following features: metrological sensitivity, appropriate mechanic and tribologic characteristics. Strong piezoresistive properties of three- component composites: metal, resin, graphite make their utilization possible for diagnosis of temperature and stress. These properties have composites of composition in surrounding of critical concentration of percolation process. The authors undertake an effort to develop models of these thermosensitive and piezoresistive properties for friction pair microcontact.
In many cases the physical properties measured using sensing elements require to multiply one of them by another. The multiplication can be realized in many ways, and in presented paper an optoelectronic system multiplying the electric signals, composed of electroluminescent diodes and photoconducting elements, is proposed. In the proposed system the linear range of the dependence of the luminance of electroluminescent diode on the current and the linear dependence of the conductance of photo-conducting element on the illumination are utilized. The output signal from the multiplying system can be an electric signal, or in another version can have the shape of a light signal, sent on by an optical fiber.
In this article we discuss the main directions of changes in organization of combustion process in industrial power boilers. We describe the fiber optic system permitting the measurement of flicker of the single coal-dust burner as well as the influence of the input conditions (primary air, secondary air) on changes of flicker. The solution operating in boiler in the `Kozienice' Power Plant was shown, as well as examples of measurement results made using a device built by authors. They confirmed the thesis that a flame flicker can be utilized for its quality evaluation.
The paper presents the results of investigations carried out in the Research Centers in Cracow concerning intelligent sensors of temperature and flow. Design assumptions and technological details of manufacturing process are described. Final characteristics of sensor prototypes are given. Some examples of application of sensors are demonstrated and the development trends are discussed.
Trap detectors may be used as absolute spectral responsivity standards or as transfer standards, which are calibrated against the cryogenic radiometer. The significant applications of trap detectors in optical radiation radiometry are described. The advantages and some metrological properties and the different configuration of trap detectors are briefly presented.
The full characterization of a detector requires the calculation of the detectivity (D*), based on responsivity and noise equivalent power measurement. In this paper we present a system, developed for noise measurements of micromachined bolometers designed and produced at the VTT Electronics. Measurement results are presented and some ideas for improvement of the developed measuring system, are discussed.
Infrared thermography has become a way to monitor thermal abnormalities present in number of diseases and physical injuries. It is used as an aid to diagnosis, prognosis and therapy. Results obtained using the last generation of equipment (computer assisted thermographic systems, detectors without liquid nitrogen cooling system) and new techniques as dynamic thermography with independent source of driving radiation shows that it is a reliable tool for medical assessment and diagnosis. Most important--the Infrared Thermography is a non-invasive measurement technique, with non-stress for patients. This paper describes Intraoperative Thermoangiography during coronary bypass surgery.
Comparison of main construction of sensing probes for measurements of electrical properties of living tissues is presented. Original solution giving very good results in a broad range of frequency is described.
This paper deals with the experimental measurements, data filtering and theoretical representation of the angular position of a human led in 3D space during normal and pathological walking. The angular position of a human leg during walking in sagittal plane was measured by a new electrogoniometer made by a UK company named Penny & Giles. This system is a spatial mechanism made of a group of links which are coupled by proper angular sensor. This instrument enables an indirect evaluation of the angular position of a human leg in the 3D space from knowledge of the system geometry and from the angular value readings. This instrument is light, small-sized technologically new and is easy to use. However, its dynamics features have not been analyzed in the literature. Therefore we decided to analyze the instrument in order to built a DWT (Discrete Wavelets Transform) filter for filtering data recorded by a electrogoniometer Penny & Giles. We built filter corresponding to Daubechies wavelets, DAUB #20. The DWT filter is sufficient for filtering high frequency noise which exists during experimental measurement of the angular position of a human leg during normal and pathological gait. Filtering using Daubechies wavelets--DAUB #20 is more efficient than commercial numerical filtering delivered by Penny & Giles company.
The new method of measurement signal processing applied in the oscillometric viscometer is presented. The method consists in analog integration of a current in the electromagnetic speaker-like actuator. Integration in displacement domain is replaced by the integration in time domain during the period of oscillations. This method of signal processing has advantages as compared to simple amplitude measurement methods i.e. first of all, better resistance to disturbing mechanical vibrations close to the working frequency of oscillations. The measuring circuit is practically insensitive to thermal drifts of electrical zeros and gains and thermal fluctuations of mechanical parameters as well. Also nonlinearities of static characteristics (e.g. of bellows) have a negligible contribution as far as a result of measurements is concerned. Some design aspects and results of examinations concerning a clinical model of the viscometer are presented. The described method of signal processing may be applied in different types of viscometers.
In this paper we present some of the newest solutions of the direct and the indirect methods of x-ray and (gamma) -ray detection applicable in medicine. We mainly describe technological postulations and several properties of linear and 2D x-ray and (gamma) -ray sensors using scintillator films, pin photodiode matrices and amorphous silicon thin film transistors.
Miniature high-sensitive pressure sensors on the basis of semiconductor whiskers and laser recrystallized SOI layers have been developed. Design examples of the sensors and some devices for medical purpose are presented.
European R&D policy in microsystems technology (MST) basically aims at the strategic goal of promoting MST uptake by European industries, in order to strengthen and secure Europe's competitiveness world-wide. Towards that common goal, both a supporting infrastructure and specific R&D programs, funded either by European or by national authorities, have been (or are being) established. This paper wants to given an overview of the different approaches with which those different initiatives try to contribute to achieving that goal.