Jerzy Kalenik

A cantilever optical-fiber accelerometer

Abstract A simple fiber-optic acceleration sensor has been designed and evaluated. It is an amplitude-modulation sensor, which employs inexpensive electronic instrumentation. The construction and technology of the sensor are presented. The influence of some construction parameters on sensor characteristics has been considered and measured. It is proved that simple construction modifications allow some sensor parameters to be tuned. The sensor characteristic is nonlinear. The amplitude-modulation depth reaches 50% at an acceleration of 250 m/s 2 for a cantilever length of 40 mm. The maximum operating frequency is dependent on cantilever length and for length 20 mm is 125 Hz.

Long time stability of lamps with nanostructural carbon field emission cathodes

A luminescent lamp with field emission cathode was constructed and tested. Phosphor excited by electrons from field emission cathode is the source of light. The cathode is covered with nickel-carbon film containing multilayer carbon nanotubes that enhance electron emission from the cathode. Results of luminance stability measurements are presented. Luminance of elaborated luminance lamp is high enough for lighting application. Long term stability (1000 hours) is satisfactory for mass lamp application. Initial short time decrease of luminance is still too high and it needs reduction.

GAIN PREDICTION THEORY OF SINGLE FOIL GAS ELECTRON MULTIPLIER DETECTOR

Gain prediction theory of single foil Gas Electron Multiplier detector was developed. Gas electron multiplier (GEM) detector with single foil was developed. Soft X-ray spectra with an energy of 5.9 keV emitted by the isotope Fe-55 were measured. On this basis, the dependence of gain and energy resolution from the detector voltage was determined. The simple theory of gain dependence on various detector parameters was developed. Preliminary results of the study confirmed the potential usefulness of the GEM detector as a substitute for the multiwire proportional chamber.

Optical properties of lamps with cold emission cathode

A luminescent lamp was constructed and tested. Phosphor excited by electrons is the source of light. The source of electrons is field emission cathode. The cathode is covered with nickel-carbon layer containing carbon nanotubes that enhance electron emission from the cathode. Results of luminance measurements are presented. Luminance is high enough for lighting application.

Thermal properties of modified carbon films

Purpose – The purpose of this paper is to present thermal properties of palladium-carbon films prepared by physical vapour deposition (PVD)/chemical vapour deposition (CVD) methods. Design/methodology/approach – Thin palladium-carbon films were prepared at Tele- and Radioresearch Institute. Test structures containing palladium-carbon films and titanium electrodes were made. Temperature-resistance characteristics were measured. Findings – The results show strong temperature dependence of modified carbon film resistance. The dependence is stable, and so modified carbon films can be applied for various electronic applications. Originality/value – The paper presents thermal properties of thin palladium-carbon prepared by original PVD/CVD method at Tele- and Radioresearch Institute.

Influence of temperature and humidity on titanium electrodes intended for an above normative conditions sensors

A series of test titanium electrodes, intended for a new generation of hydrogen and hydrogen compounds sensors was prepared. This new generation of hydrogen sensors is expected to operate in above normative conditions. In order to investigate the influence of temperature and moisture on titanium electrodes a series of experiments was conducted. Test samples were exposed to elevated levels of temperature (up to 165°C) and moisture (relative humidity up to 80%). These test allowed to measure resistivity as a function of temperature and to determine the long-term stability of electrical parameters of electrodes. Results of this studies will be used in fabrication of reliable electrodes for a new generation of hydrogen sensors.

Properties of carbonaceous-palladium hydrogen sensor

In this paper we present studies of hydrogen sensors based on nanostructural C-Pd films deposited on alundum substrate with silver or titanium electrodes. These C-Pd films were prepared by PVD method. Films were characterized by SEM and EDS. Sensitivity of films toward hydrogen were measured in specially prepare experimental set-up with small chamber (50ml). Response time was also registered for different percentage of hydrogen / nitrogen mixture (up to 1% of hydrogen).

Influence of selected environmental factors on electrical and physical properties of polymer-semiconductor layers

An attempt to investigate the changes of luminance of alternating-current electroluminescent lamps (ACEL) during first 12 hours of operation and the influence of moisture on this process was undertaken. A series of test ACEL lamps was degraded in dry and humid air. The changes were dependent on humidity of storage and working atmosphere.

Investigation of luminescence excited by electrons from cold emission from a carbon nanotube cathode

The paper presents the way that colour can serve solving the problem of calibration points indexing in a camera geometrical calibration process. We propose a technique in which indexes of calibration points in a black-and-white chessboard are represented as sets of colour regions in the neighbourhood of calibration points. We provide some general rules for designing a colour calibration chessboard and provide a method of calibration image analysis. We show that this approach leads to obtaining better results than in the case of widely used methods employing information about already indexed points to compute indexes. We also report constraints concerning the technique. Nowadays we are witnessing an increasing need for camera geometrical calibration systems. They are vital for such applications as 3D modelling, 3D reconstruction, assembly control systems, etc. Wherever possible, calibration objects placed in the scene are used in a camera geometrical calibration process. This approach significantly increases accuracy of calibration results and makes the calibration data extraction process easier and universal. There are many geometrical camera calibration techniques for a known calibration scene [1]. A great number of them use as an input calibration points which are localised and indexed in the scene. In this paper we propose the technique of calibration points indexing which uses a colour chessboard. The presented technique was developed by solving problems we encountered during experiments with our earlier methods of camera calibration scene analysis [2]-[3]. In particular, the proposed technique increases the number of indexed points points in case of local lack of calibration points detection. At the beginning of the paper we present a way of designing a chessboard pattern. Then we describe a calibration point indexing method, and finally we show experimental results. A black-and-white chessboard is widely used in order to obtain sub-pixel accuracy of calibration points localisation [1]. Calibration points are defined as corners of chessboard squares. Assuming the availability of rough localisation of these points, the points can be indexed. Noting that differences in distances between neighbouring points in calibration scene images differ slightly, one of the local searching methods can be employed (e.g. [2]). Methods of this type search for a calibration point to be indexed, using a window of a certain size. The position of the window is determined by a vector representing the distance between two previously indexed points in the same row or column. However, experiments show that this approach has its disadvantages, as described below. * E-mail: A.Nowakowski@ire.pw.edu.pl Firstly, there is a danger of omitting some points during indexing in case of local lack of calibration points detection in a neighbourhood (e.g. caused by the presence of non-homogeneous light in the calibration scene). A particularly unfavourable situation is when the local lack of detection effects in the appearance of separated regions of detected calibration points. It is worth saying that such situations are likely to happen for calibration points situated near image borders. Such points are very important for the analysis of optical nonlinearities, and a lack of them can significantly influence the accuracy of distortion modelling. Secondly, such methods may give wrong results in the case of optical distortion with strong nonlinearities when getting information about the neighbouring index is not an easy task. Beside this, the methods are very sensitive to a single false localisation of a calibration point. Such a single false localisation can even result in false indexing of a big set of calibration points. To avoid the above-mentioned problems, we propose using a black-and-white chessboard which contains the coded index of a calibration point in the form of colour squares situated in the nearest neighbourhood of each point. The index of a certain calibration point is determined by colours of four nearest neighbouring squares (Fig.1). An order of squares in such foursome is important. Because the size of a colour square is determined only by the possibility of correct colour detection, the size of a colour square can be smaller than the size of a black or white square. The larger size of a black or white square is determined by the requirements of the exact localisation step which follows the indexing of calibration points [3]. In this step, edge information is extracted from a blackand-white chessboard. This edge information needs larger Artur Nowakowski, Wladyslaw Skarbek Institute of Radioelectronics, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warszawa, A.Nowakowski@ire.pw.edu.pl Received February 10, 2009; accepted March 27, 2009; published March 31, 2009 http://www.photonics.pl/PLP

The use of ultrasonic bonding for components assembly in printed circuit boards

The lately developed method of electronic components attachment to solder pads in printed circuit boards is presented. The method employs ultrasonic vibration to the attachment process. Some 0402 electronic components were attached to the solder pads in the in printed circuit board. Shear force and joint electrical resistance were measured to assess the joints quality. The authors for the strongest joints reached shear force of 3N last year. The application of more powerful ultrasonic bonder let to reach shear force about 15N. This level of shear force is satisfactory but still lower than shear force for soldered components that reaches 20N. The method is not mature yet and it should be developed. The results of this research show that it is possible to reach better results by attachment process parameters optimisation.