Michael L. Korwin-Pawlowski

Pressure sensing using periodically tapered long-period gratings written in photonic crystal fibres

This paper reports on the first application of tapered long-period gratings (TLPGs) written in photonic crystal fibres (PCFs) using a cost-effective computer-assisted precision arc-discharge apparatus for conducting direct measurements of hydrostatic pressure up to 180 bar. The developed TLPG-PCF device displays significant potential as a highly sensitive and cost-effective pressure sensor, with a pressure sensitivity of 11.2 pm bar?1. A negligible temperature sensitivity of about 0.3 pm ?C?1 of the sensor output signal was observed within the temperature range from 5 ?C to 65 ?C.

Refractive index sensing of fiber optic long-period grating structures coated with a plasma deposited diamond-like carbon thin film

Long-period grating (LPG) structures including cascaded LPGs on step index fibers and photonic crystal fibers were coated with thin films of diamond-like carbon (DLC) using plasma deposition techniques. Improvements in the coating procedures increased sensitivity to external refractive index variations indicating significant improvements in sensing capability of the hybrid structures. DLC films in the range of tens of nanometers significantly increased sensitivity of all the structures tested.

A Method of Examination of Liquids by Neural Network Analysis of Reflectometric and Transmission Time Domain Data From Optical Capillaries and Fibers

This paper presents the construction and working principles of an intelligent fiber-optic sensor used for liquid examination using time domain data. The sensing elements consisted of a length of optical fiber or a short section of optical capillary and worked either on the reflection intensity basis or on transmission intensity basis. The changes of the monitored signal are caused mainly by the variation in light propagation conditions at the interfaces of liquid and gaseous phases and formation of drops of liquids or lenses at liquid-vapor interfaces. The physical effects on which depends the formation of a drop of liquid or a lens are surface tension, viscosity, boiling point, vapor pressure of liquid and its heat capacity. They provide information allowing determining the type of the liquid by a procedure which includes submerging, submersion, emerging and emergence of the sensing head from the examined liquid, or by local heating of the liquid sample. The measured data were analyzed using neural networks.

Technology and characterization of 4H-SiC p-i-n junctions

Silicon Carbide (SiC) photodiodes have been proposed in recent years for ultraviolet (UV) light detection because of their robustness even in harsh environments, high quantum efficiency in all the UV range (200nm-400nm), excellent visible and infra-red blindness excluding UV filters implementation, low dark current and high speed. 4H-SiC has a bandgap three times larger (3.26eV) than Si and, thus, SiC detectors should have much higher sensitivity than Si detectors. In this paper, we present an overview of results on 4H-SiC p-i-n junctions fabrication and characterization. We used implantation technique to obtain p-region of the investigated structure. The ohmic contacts were formed using evaporation, etching and lift-off. Current-voltage, contact resistance and electroluminescence are the main characteristics of the presented devices. All the diodes showed excellent rectification with leakage current density of less than 10-9A/cm2.

A method of examination of liquids by neural network analysis of reflectometric time domain data from optical capillaries and fibers

This paper presents the construction and working principles of a reflectometric intelligent fiber-optic sensor used for liquid examination. Unlike other well-known fiber optical sensors which use information from optical wavelength variations, the proposed system uses time domain data. The sensing element consists of a length of optical fiber and a short section of optical capillary and works on the reflection intensity basis. The reflected signal level depends on the optical construction of the sensor element. The changes of the monitored signal are caused mainly by variation in light propagation conditions at the interfaces of liquid and gaseous phases. The physical effects involved are Fresnel reflection, local numerical aperture variation and liquid lenses formation. It is possible to call out across the changes of those effects by introducing a measuring procedure which includes submerging, submersion, emerging and emergence of the sensing head from the examined liquid or by local heating of the liquid sample.

Intelligent Photonic Sensors for Application in Decentralized Wastewater Systems

Michal Borecki1, Michael L. Korwin-Pawlowski2, Maria Beblowska1, Jan Szmidt1, Maciej Szmidt3, Mariusz Duk4, Kaja Urbanska3 and Andrzej Jakubowski1 1Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, 2Departement d’informatique et d’ingenierie, Universite du Quebec en Outaouais, 3Warsaw University of Life Sciences, 4Lublin University of Technology, 1,3,4Poland 2Canada

Modeling of a multicharged ion beam line using SIMION

Multicharged ion beams (MCI) are promising tools to probe or modify the surface of materials with applications in microelectronics and nanotechnology. Ion beam lines are parts of the MCI systems connecting the ion source with the processing chamber and they perform the function of extracting, accelerating, decelerating, focusing and scanning the ion beam on the surface of the target. In our work we present results of modeling of an MCI beam line using the SIMION code to simulate the flight of ions, with the purpose of optimizing the yield of the line and avoiding spurious effects due to interaction of the ions with the metallic elements of the line, such as heating, outgassing and excessive Xray emission. We show that a two stage ion extractor could significantly reduce ion beam losses.

Non-invasive method of car wheel rim examination

This paper presents the concept of a non-invasive method to determine the technical state of passenger car wheel rims. The method consists of a series of vibration and dimension measurement on a rim mounted in a diagnostic station. The measurements are taken on four positions of the rim of rotation versus constant excitation point angular position. The wheel rim’s natural frequencies distribution versus time and rotation angle are examined as diagnostic tool of rim fit for use classification from materials fatigue point of view. These characteristics are also inspected to determine the condition of joints of rim elements and to identify the cracks or loss of integrity in the wheel rim structure. The wheel rim dimensions as a series of specific diameters are examined for wheel rim radial run-out and for axial run-out. The proposed method was evaluated for a new and worn out rims. Performed experiments show that the natural frequency values of rim, the damping factor of natural rim vibration and rim diameters course grouped in a spider chart allows an effective visual classification of car rim fit for use.

Automatic detection of outlier data received in multi-parametric capillary sensors of diesel fuels fit for use

The multi-parametric capillary sensor with local sample heating has been shown as an effective tool for diesel fuel fit for use classification at the laboratory level of technology, where a trained operator performs the experiments. The sensor consists of disposable capillary optrode, head and measurement control unit. An increase of the technology level of the sensor requires automation of samples handling and implementing automatic rejection of uncertain outlier data. Such data uncertainty may come from variations of capillary optrode diameters, inaccuracy of optrode filling with sample, inaccuracy of corking the sample as well as inaccuracy of optrode positioning in the head. Mentioned inaccuracies of preparation of the measurement may lead to outlier data, which impacts the correctness of sample classification. In this paper automatic detection of outlier data received in multi-parametric capillary sensors of diesel fuels is proposed and examined with data collected by untrained and trained operators. Performed experiments show that direct statistical tools applied to raw data lead to improper results of outlier data pointing. The proper outlier data pointing taking place for raw data converted to vector pattern of data on the base of physical phenomena described by experimental data or with the use of analysis of first derivative of raw data characteristic points course.

The working condition of a short section of optical capillary in multi-parameters heads for lab-on-fiber application

This paper presents the proposition of a novel integration method of multi-parameter heads to be used for examination of liquids with short sections of locally heated optical capillaries. The first implementation of the proposed method concerns is a light source fiber and a detection fiber inserted into the capillary hole. In such a setup the local heating causes switching of the hole modes into the tube modes. Therefore, unlike other well-known fiber optical sensors for liquids that utilize spectral information of the index of refraction and optical signal attenuation, the short section capillary method takes advantage of additional information originating from surface tension, viscosity, boiling point, vapor pressure of liquid and its heat capacity. The setup with fibers can be easily used in a laboratory environment. For an in-situ application such construction is not recommended, because introducing the fiber into the capillary can generate small vapor bubbles. Therefore, direct side coupling of the capillary and a semiconductor light source is needed. We show that the hole modes excitation is possible with satisfactory working parameters when soda glass capillaries are preconditioned using a relatively simple technique.