Metrology and Measurement Systems

Direct sensor-to-microcontroller is a simple approach for direct interface of passive modulating sensors to a microcontroller without any active components in between the sensor and the microcontroller and without an analog to digital converter. The metrological performances of such interface circuits are limited by certain microcontroller parameters which are predetermined by the manufacturing technology. These limitations can be improved by specific hardware-related techniques and can improve the accuracy, speed and resolution of the measurements. Such hardware solutions as well as proper selection of the electrical components are addressed in this paper. It has been shown that employment of only a few MOSFET transistors can reduce the maximal relative error of single point calibration more than fifteen times and can increase the measuring speed around 30 % in all calibration techniques in the measurement range of PT1000 resistive temperature sensors. Moreover, the effective number of resolution bits increases by more than 1.3 bits when using an external comparator.

In situ monitoring of the thickness of thin diamond films during technological processes is important because it allows better control of deposition time and deeper understanding of deposition kinetics. One of the widely used techniques is laser reflectance interferometry (LRI) which enables non-contact measurement during CVD deposition. The authors have built a novel LRI system with a 405 nm laser diode which achieves better resolution compared to the systems based on He-Ne lasers, as reported so far. The system was used for in situ monitoring of thin, microcrystalline diamond films deposited on silicon substrate in PA-CVD processes. The thickness of each film was measured by stylus profilometry and spectral reflectance analysis as a reference. The system setup and interferometric signal processing are also presented for evaluating the system parameters, i.e. measurement uncertainty, resolution and the range of measurable film thickness.

The paper presents the results of the analysis of the striker shape impact on the shape of the mechanical elastic wave generated in the Hopkinson bar. The influence of the tensometer amplifier bandwidth on the stress-strain characteristics obtained in this method was analyzed too. For the purposes of analyzing under the computing environment ABAQUS / Explicit the test bench model was created, and then the analysis of the process of dynamic deformation of the specimen with specific mechanical parameters was carried out. Based on those tests, it was found that the geometry of the end of the striker has an effect on the form of the loading wave and the spectral width of the signal of that wave. Reduction of the striker end diameter reduces unwanted oscillations, however, adversely affects the time of strain rate stabilization. It was determined for the assumed test bench configuration that a tensometric measurement system with a bandwidth equal to 50 kHz is sufficient

In this paper the design and implementation of a plug-and-play analog resistance temperature sensor is presented. The smart temperature sensor consists of an analog sensor element with transducer electronic data sheet (TEDS) memory device and a network- capable application processor (NCAP) connected through a mixedmode interface (MMI). The mixed-mode interface and NCAP front-end electronic support have been implemented by the use of a standard 8-bit microcontroller. NCAP's application processing and network communication functions are implemented based on the concept of virtual instrumentation using a PC. The implemented NCAP can also be used as a plug-and-play stand-alone data acquisition system or as development system for plug-and-play sensors compliant with the IEEE 1451.4 standard. Details of sensor implementation and test results are included in the paper.

In this paper a measurement system for determination of supercapacitor equivalent parameters is proposed. Specific properties of materials used for supercapacitor construction require some advanced tools and measurement procedures to be applied during tests. The measurement system allows to measure values of equivalent parameters by both the DC and AC method whilst keeping appropriate time criteria required by this type of devices. Furthermore, in this paper the most relevant properties and measurement capabilities of the proposed system are described as well as some exemplary values of the supercapacitor equivalent parameters measured experimentally are presented.

Temperature change is one of key factors which should be taken into account in logistics during transportation or storage of many types of goods. In this study, a passive UHF RFID-enabled sensor system for elevated temperature (above 58°C) detection has been demonstrated. This system consists of an RFID reader and disposable temperature sensor comprising an UHF antenna, chip and temperature sensitive unit. The UHF antenna was designed and simulated in an IE3D software. The properties of the system were examined depending on the temperature level, type of package which contains the studied objects and the type of antenna substrate.

This paper presents a method of correcting the effects caused by refraction phenomena in an optical measurement system. The correction algorithm proposed can be applied in many different photogrammetric applications affected by these effects. To validate this algorithm, a foot sole optical measurement system that uses several cameras to build a mesh of a foot sole has been used. This measurement system has six cameras that are protected by a safety glass that separates the cameras from the foot to be measured. The safety glass produces an air-glass-air interface that causes the refraction phenomena, producing deformations in the images. Due to the deformations it is impossible to obtain reliable metric information of the images captured using the measurement system. The developed correction algorithm is based on a grid layout and associated polynomials and makes it possible to correct the deformations and extract accurate metric information.

In this paper a survey of analog application specific integrated circuits (ASICs) for low-level image processing, called vision chips, is presented. Due to the specific requirements, the vision chips are designed using different architectures best suited to their functions. The main types of the vision chip architectures and their properties are presented and characterized on selected examples of prototype integrated circuits (ICs) fabricated in complementary metal oxide semiconductor (CMOS) technologies. While discussing the vision chip realizations the importance of low-cost, low-power solutions is highlighted, which are increasingly being used in intelligent consumer equipment. Thanks to the great development of the automated design environments and fabrication methods, new, so far unknown applications of the vision chips become possible, as for example disposable endoscopy capsules for photographing the human gastrointestinal tract for the purposes of medical diagnosis.

The article proposes a method for measuring discomfort glare which uses numerical description of the phenomenon in the form of a digital luminance distribution map recorded on a CCD array. Essential procedures for determining partial quantities which are necessary for calculation of UGR index are discussed in detail, along with techniques for measuring position index and size of light sources, with regard to the parameters of the registering system and coordinates of the images of the sources on the array.

Noise spectroscopy and I-V characteristic non-linearity measurement were applied as diagnostic tools in order to characterize the volume and contact quality of positive temperature coefficient (PTC) chip sensors and to predict possible contact failure. Correctly made and stable contacts are crucial for proper sensing. I-V characteristics and time dependences of resistance were measured for studied sensors and, besides the samples with stable resistance value, spike type resistance fluctuation was observed for some samples. These spikes often disappear after about 24 hours of voltage application. Linear I-V characteristics were measured for the samples with stable resistance. The resistance fluctuation of burst noise type was observed for some samples showing the I-V characteristic dependent on the electric field orientation. We have found that the thermistors with high quality contacts had a linear I-V characteristic, the noise spectral density is of 1/f type and the third harmonic index is lower than 60 dB. The samples with poor quality contacts show non-linear I-V characteristics and excess noise is given by superposition of g-r and 1/fn type noises, and the third harmonic index is higher than 60 dB.

In this paper the method of fast impedance spectroscopy of technical objects with high impedance (|Zx| ≥1 GΩ) is evaluated by means of simulation and a practical experiment. The method is based on excitation of an object with a sinc signal and sampling the response signals proportional to current flowing through and voltage across the measured impedance. The object’s impedance spectrum is obtained with the use of continuous Fourier transform on the basis of linear approximations between samples in two acquisition sections, connected with the duration of the sinc signal. The method is first evaluated in MATLAB by means of simulation. An influence of the sinc signal duration and the number of samples on impedance modulus and argument measurement errors is explored. The method is then practically verified in a constructed laboratory impedance spectroscopy measurement system. The obtained acceleration of impedance spectroscopy in the low frequency range (below 1 Hz) and the decrease of the number of acquired samples enable to recommend the worked out method for implementation in portable impedance analyzers destined for operation in the field.

The paper stresses the issue of strong temperature influence on the gain of a Silicon Photomultiplier (SiPM). High sensitivity of the detector to light (single photons) requires stable parameters during measurement, including gain. The paper presents a method of compensating the change of gain caused by temperature variations, by adjusting a suitable voltage bias provided by a precise power module. The methodology of the research takes in account applications with a large number of SiPMs (20 thousand), explains the challenges and presents the results of the gain stabilization algorithm.

A high pressure resonator transducer (0 to 100 MPa) devised by the author has been described. The elastic element of the converter consists of a cylinder with an offset arranged axis hole. Quartz resonators were used for the measurement of deformations of the pipe. Based upon the results of the transducer testing, a new algorithmic method for the minimizalizsation of the temperature error, that eliminates the need for a temperature gauge has been worked out.

Testing of varistors using thermography was carried out in order to assess their protective properties against possible overvoltage phenomena in the form of high-level voltage surges. An advantage of the thermography technique is non-contact temperature measurement. It was proposed to assess the properties of varistors working in electronic devices as protective elements, on the basis of estimating temperature increments on varistor surfaces, registered by an infrared camera during surge resistance tests with standard voltage levels. To determine acceptable temperature increments on a tested varistor, preliminary testing was performed of P22Z1 (Littelfuse) and S07K14 (EPCOS) type varistors, working first at a constant load and presently during surge tests,. The thermographic test results were compared with measured varistor capacity values before and after tests. It was found that recording with thermography temperature increments greater than 6°C for both P22Z1 and S07K14 varistor types detects total or partial loss of varistor protective properties. The test results were confirmed by assessment of protective properties of varistors working in output circuits of low nominal voltage devices.

This paper outlines a measurement method of properties of microstructured optical fibers that are useful in sensing applications. Experimental studies of produced photonic-crystal fibers allow for a better understanding of the principles of energy coupling in photonic-crystal fibers. For that purpose, fibers with different filling factors and lattice constants were produced. The measurements demonstrated the influence of the fiber geometry on the coupling level of light between the cores. For a distance between the cores of 15 μm, a very low level (below 2%) of energy coupling was obtained. For a distance of 13 μm, the level of energy transfer to neighboring cores on the order of 2-4% was achieved for a filling factor of 0.29. The elimination of the energycoupling phenomenon between the cores was achieved by duplicating the filling factor of the fiber. The coupling level was as high as 22% in the case of fibers with a distance between the cores of 8.5 μm. Our results can be used for microstructured-fiber sensing applications and for transmission-channel switching in liquid-crystal multi-core photonic fibers.

This paper proposes a method for adjusting light waves propagating in systems composed of photonic fibers, light sources and detection elements. The paper presents the properties of these connections in terms of the loss of signal transmission. Different fiber core areas were analyzed, and measurements of the mode-field diameters (MFDs) of selected fiber structures are presented. The study analyzed two types of LMA (Large Mode Area) fiber structures, and the mode-field diameters of these structures were measured on the basis of the radiation distribution obtained under near-field conditions. The results are compared to the values obtained for a SMF-28 single-mode fiber. The LMA structures analyzed in the paper are characterized by low sensitivity of the MFD parameter to the length of transmitted waves, which creates the possibility of their use as intermediate fibers when connecting optical fibers of different diameters. In the wavelength range from 800 nm to 1600 nm, a 3.5% MFD change was observed for the first investigated LMA structure, and a 1% change was observed for the second. In addition, measurements of the mode-field diameters were also made using the transverse offset method for comparison of the results.

New research trends in energy grids and water networks push toward ICT solutions for allowing remote metering of consumption. In the paper, after an introduction to the European Standards on smart metering, two visual sensors thought to solve typical metering problems in water public networks are described. Particular detail is given hardware and software solutions and the perspective of integration with analog gas and electric energy metering devices.