Metrology: Inspection and Characterisation Methods

PID161133

Fiber optic temperature sensor based on spectral transmitivity of CdTe

Z.V. Djinovic a,b, M.C. Tomic c, S. Ivankovic c, A. Vujanic b

a Institute of Sensor and Actuator Systems, Vienna University of Technology, Vienna 1040, Austria
b Integrated Microsystems Austria, Wiener Neustadt 2700, Austria
c Institut Bezbednosti, Belgrade 11000, Serbia and Montenegro

Abstract

A fiber optic sensor for measurement of temperature in an environment with strong electromagnetic interferences is presented. The method is based on the change of energy gap of single crystal CdTe with temperature. The spectral transmission of sensing crystal is detected by a special spectrometric arrangement using a diffraction grating and a linear CCD sensor. The obtained measurement uncertainty is lower then ±1ºC, in the measuring range from 15ºC to 100ºC, with the data rate of several hertz.

Keywords temperature measurement, fiber optic sensor, CdTe, spectrometer

Mechanical testing of laser welded micro seams

C.B. Nielsen a, D.Buccoliero a, T. Ussing b
a Centre for Microtechnology and Surface Analysis, Danish Technological Institute, 2630 Taastrup, DK
b Fluimedix ApS, Gregersensvej, 2630 Taastrup, DK

Abstract

In a previous work, a low power diode laser has been presented, which is capable of creating laser welded seams as narrow as 10 μm in polymers. The ability to produce narrow seams makes this low power diode laser suitable for perimeter welding of micro fluidic channels in Lab On a Chip (LOC) systems. Perimeter welding is useful when bonding polymeric LOC systems since clogging of the micro channels is prevented during the bonding procedure. In the present work a new mechanical test method is put forward that tests the mechanical strength and homogeneity of a laser welded micro seam, both of which is important when a micro seam is used to bond the lid in a LOC. The test is a pressure test, where the weld seam is subjected to the stress that arises from an isostatic pressure in a cavity that is defined by two pieces of polymer and the weld seam in question. The paper presents the experimental work together with mechanical finite element simulations, both of which show how the mechanical test results are affected by the width of the laser welded micro seam. Among the results the yield pressure-seam width relationship is shown to have a contra intuitive behavior. Instead of having an ever decreasing yield pressure for decreasing seam widths, a local minimum in this relationship is found.

Keywords Mechanical testing, micro welding, Lab on a chip, micro fluidics

Reactive magnetron sputtering deposited ITO thin films : influence of O2 admixture on microstructure and optical properties

C. Secouarda,b, C. Ducros a, P. Roca i Cabarrocas b, S. Noël c, F. Sanchette a

a CEA Grenoble, Laboratoire des Technologies des Surfaces, 17 rue des Martyrs 38054 Grenoble CEDEX, France
b Laboratoire de Physique des Interfaces et des Couches Minces (CNRS UMR 7647), Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex, France
c CEA Grenoble, Laboratoire des Composants Hybrides, 17 rue des Martyrs 38054 Grenoble CEDEX, France

Abstract

Indium-tin oxide (ITO) thin films have been deposited onto glass substrates by reactive magnetron sputtering. Effects of O2 content in Ar/O2 gas mixture on coatings properties were investigated. The structure was analysed by X-ray diffraction. In the region between 0 and 8 O2 vol.% in the gas mixture the crystallisation is improved and the lattice is expanded with increasing oxygen flow rates because of the incorporation of the overflowing oxygen. Above 8 O2 vol.% in the gas mixture the lattice is shrunk and the crystallinity is lowered. The crystallites size decreases with increasing oxygen flow rate after reaching a maximum at 4 O2 vol.% in the gas mixture. In fact, the excess oxygen is bound to be segregated to the grain boundaries preventing the grain growth and relaxing the lattice. The optical transmittance of the films was determined using a spectrophotometer. The transparency improves with increasing oxygen flow rates. The filling of oxygen vacancies and the deactivation of Sn donors both explain the red-shift in the UV region and the great increase of the transmittance in the near
infra-red region. Good transmission rates (>80%) seem promising for photovoltaic application.

Keywords indium tin oxide, reactive magnetron sputtering, X-ray diffraction, transmittance

Comparison of the control of laser striation on lamellar cast iron with various techniques

C. Vincent a, b, G. Monteil a, T. Barrière b, J.C. Gelin b
a Laboratoire de Microanalyse des Surfaces, 26 chemin de l'épitaphe 25000 Besançon, France
b Institut FEMTO-ST, département mécanique appliquée, 24 chemin de l'épitaphe 25000 Besançon, France

Abstract

After engraving specific grooves by means of a laser Nd:YAG, three measurement techniques have been used in order to control the shape and geometry of the grooves. Different types of grooves have been studied. They are defined by their profiles and their spatial repartition. The first characteristic is the profile. Four cross section geometries have been selected: hemispherical, rectangular, trapezoidal and triangular. The second characteristic is the spatial distribution. The grooves are classified in two categories: continuous and discontinuous lines with a specific pattern for each one. The engraved material is lamellar cast iron which is a heterogeneous material. Consequently, the conditions of engraving are more difficult to define. Thus, an accurate metrology is the key point to adjust the laser machining in order to obtain the desired grooves.

Three measuring techniques have been used to control one or more characteristics of the grooves like dimensions, distribution or profile. These techniques are: roughness profilometry, scanning electronic microscope and non contacting optical imaging. Combining information coming from those techniques, we lead to a better control of the geometry of the engraved surfaces.

Keywords roughness profilometer, scanning electronic microscope, non contacting measurement, laser machining.

Measurement and characterisation of the microtopography in the contact area between workpiece and tool in microforming

S. Weidel, U.Engel
Chair of Manufacturing Technology, University of Erlangen-Nuremberg,
Egerlandstr. 11, D-91058 Erlangen, Germany

Abstract

In metal forming processes, the forming load is transmitted from the tool to the workpiece only by a certain fraction of the nominal contact area. According to the mechanical-rheological model these fractions are mainly the real contact area (RCA) and the so-called closed lubricant pockets (CLP). As the number of these contact areas (RCA and CLP) is reduced drastically in micro forming processes due to small part dimensions and approximately scale invariant surface topographies, their influence on the tribological conditions is increased significantly. Therefore, the knowledge about the real contact state in these areas in micro forming is much more important compared to conventional “macro” length scale. In the macro case, the real contact area is regarded as completely flattened during the forming process while the sub-topography which emerges on single asperities is not considered. In the present study, a test rig is introduced for the characterisation of the flattening behaviour of single asperities by in-situ observation and for the recording of the force-displacement characteristics. Additionally, a strategy for the evaluation of the sub-topography on single asperities is presented leading to an improved understanding of the tribological behaviour in micro forming processes. Thus, an improved simulative process design of micro forming processes is enabled.

Keywords microforming, tribology, surface characterisation

Micro particle sizing by using of ray optics Monte Carlo code

M.D. Mikrenska a, P.I. Koulev a, J.-B. Renard b
a Institute of Mechanics, Bulgarian Academy of Sciences, Sofia, 1113, BG
b Laboratoire de Physique et Chimie de l'Environnement, CNRS, 45071 Orléans, FR

Abstract

Particle characterization and identification methods are important for many scientific and technological applications ( manufacture and quality control of particulate materials, product research and developments, etc.) and give an invaluable tool in the frontier of sciences such as biotechnology, micro and nanotechnology. The present work concerns light scattering simulation as a specific particle sizing and characterization method. Ray optics Monte Carlo light scattering software is developed and applied for the study of micro particle polarization properties as a function of the particle size. A number of numerical experiments are performed and polarization phase functions for spherical, cubic and rounded cubic micro particles with various sizes and optical properties are presented. The proposed method is verified by a comparison between calculated and measured polarization phase functions for crystals of KBr. The developed software is relatively simple and powerful tool for micro particle sizing. It could be easy integrated in systems for particle characterization and identification.

Keywords micro particle sizing, light scattering, polarization phase function, ray optics, Monte Carlo simulation

Repeatability analysis of two methods for height measurements in the micrometer range

C. Ferri a, E. Brousseau a, S. Dimov a, L. Mattsson b
a The Manufacturing Engineering Centre, Cardiff University, Cardiff CF24 3AA, UK
b Department of Production Engineering, Royal Institute of Technology, SE-10044 Stockholm, Sweden

Abstract

A precision study of two height measuring methods is carried out. The first method is based on a White Light Interferometer (WLI) and the second on a Co-ordinate Measuring Machine (CMM) equipped with an optical probe. The height measurements considered are in the range [150; 250] μm. Point and interval estimates of repeatability are reported in the paper. This study presents experimental evidence that, under repeatability conditions, the precision of the WLI method is about five times higher than that of the optical CMM method. Furthermore, the precision of WLI is constant over the investigated height range whereas a dependency of the CMM precision on the nominal dimensions is identified. For both methods a linear relationship is detected between the random error and the sequence in which the measurements are taken.

Keywords Repeatability, White light interferometry, CMM

Localizing micro-defects on rough metal surfaces.

A. Témun a, L. Mattsson a and I. Heikkilä b
a Dep. of Production Engineering, KTH - Royal Institute of Technology, SE-100 44 Stockholm, Sweden
b KiMAB, Drottning Kristinas väg 48, 114 28 Stockholm, Sweden

Abstract

In this paper we present a study of reflectance measurements to a direct metrological problem. Our aim is to estimate progressive surface wear by detecting minute defect development in surface microtopography on Ra 0.7 μm rough stainless steel surfaces subject to mechanical wear from hard particle deposits on a metal bar. The investigation was carried out by using a CMOS digital camera with a macro objective, and was ought to demonstrate how surface scattering measurements can provide a viable alternative in circumstances where traditional roughness measurement techniques fail to deliver the expected results and, due to certain restraints, laboratory-type surface measurements are not applicable either.

Our work is based upon measuring variations in the amount and direction of scattered light, reflected from the inspected surfaces, featuring microirregularities. We will show that it is possible to identify the extent of surface flaws by statistically evaluating the recorded brightness information. The developments in this paper can provide basis for a future quality control system devoted to on-line surface measurements.

Keywords surface roughness, defect assessment, reflectance, light scattering, digital camera