Table of contents

There is a current requirement to detect and quantify the presence of gas bubbles in oil exploration. For this reason a novel method has been developed to measure simultaneously the velocity, size and refractive index of large optically transparent bubbles and droplets. The method is based on the time displacement of refracted and reflected beams scattered from the moving particles. Experimental results obtained from water droplets are included.

The measurement of the total forces acting on the surface of a wind tunnel model is still the most important wind tunnel measurement technology. Either the model is mounted by struts to a balance, which is located outside the test section (an `external balance'), or the balance is located inside the model and connects the model structure to the mounting sting, which in the case of aeroplane configurations protrudes from the rear fuselage (an `internal balance'). This review concerns internal balances only. The functional principle is described and some comments on the demand for high accuracy are given. The optimization of designs for strain gauge balances, the fabrication methods and the selection of materials are commented on. The calibration theory of multi-component balances is outlined and the calibration equipment is described. Examples for conventional manual calibration equipment and for an automatic calibration machine are given. Finally the specific design features of cryogenic balances and half model balances are given. This review presents the author's experiences and developments. Since there is hardly any general literature on the subject of strain gauge balances and since the balance engineers in the world have not that much contact with each other, there may be different points of view at other institutions.

About six years ago, under the editorship of Professor Julian Jones, an initiative was started to expand the scope and geographic representation of the Editorial Board of Measurement Science and Technology. A glance at our inside cover will reveal that this initiative has indeed been very successful, with over six countries represented in a board of nine members. However, nominating and electing members alone is not enough. The goal of such measures is also to attract both authors and readers from a wider and more diverse scientific community. One follow-up action was therefore to highlight certain topical areas. We have done this in recent years with a series of special features and special issues, all of which have been extremely well received by our readership. This particular issue is, however, a very special case, since we have attempted to highlight research from one particular country: Japan.

For an editorial board as well as for a publisher, Japanese authors represent a very special segment of the publishing community. Not only is there a natural language barrier, but there are also some reservations regarding the publication of material that may already have had exposure within the Japanese community. Statistically, we recognize that the Japanese community represents a higher percentage of our readership than it does our authorship, a situation that is probably common across the scientific publishing industry. However, atMeasurement Science and Technology we are very fortunate to have two excellent Japanese representatives on our editorial board, Professor Yuji Ikeda (Kobe University) and Professor Koichi Hishida (Keio University), who were able to help dissolve these reservations for a notable number of colleagues, and to assemble a very impressive collection of articles which are featured in this issue, including one review article from Kazunari Kuwahara on the topic of diagnostics for in-cylinder measurement in gasoline engines.

The selection of articles in this feature also reflects to a large extent the research interests of our Japanese editorial board members, including measurement technologies for flows and combustion. Eight of the fourteen featured articles deal with particle image or tracking velocimetry and its applications. This is not coincidental, since Japanese researchers have traditionally been very innovative and active in this field. Almost all of the articles involve the use of lasers, again not unusual for the Japanese community. This collection of articles therefore also provides a remarkably good picture of the state-of-the-art in these areas and we hope that this finds the interest and appreciation of our readers.

As lead editor for this Japanese research activity feature, and for his untiring efforts in suggesting, planning and carrying through the organization of this issue, we thank Professor Yuji Ikeda wholeheartedly. We hope that you as a reader find the feature interesting and we would be happy to receive your feedback. As with any special feature, the demands on the publishing office are particularly great, since a large number of articles must be ready for publishing at the same time. Therefore, a special thanks goes to the Measurement Science and Technology editorial staff at IOP Publishing, for yet another smoothly executed project.

Cam Tropea Honorary Editor

In a premixed leanburn engine employing an in-cylinder rotating flow, tumble, the influence of the in-cylinder flow field structure on combustion was investigated with a two-dimensional PTV, a three-dimensional PTV and the analysis of continuous and cycle-to-cycle UV flame images. As a result, optimum combustion control was achieved by controlling the generation of turbulence. In a gasoline direct injection engine adopting a wide spacing layout, the characteristics of mixture preparation were investigated by visualizing a fuel spray with laser shadowgraphy and LIF, and deriving the mixture strength at the spark plug from spectrum analysis of spark discharge emission. Also, the combustion characteristics were investigated by analysing flame emission spectra continuously, and imaging UV luminescence and thermal radiation of flame emission simultaneously. Consequently, it was clarified that combustion control is achieved by controlling air-fuel mixing.

It is very important to know the temperature history in a spark-ignition engine when the phenomenon of knocking is being studied. However, measurement of the gas temperature is not easy and some work has been done using laser diagnostics etc. In this study, the temperature history until the time of occurrence of knocking in a spark-ignition engine was measured by a form of laser interferometry designed especially for use in the combustion chamber. Not only the change in temperature but also the absolute value of the temperature could be determined with this interferometer, by utilizing the change of the gas density on the reference side. This is a non-intrusive measurement and high resolution is expected. The temperature resolution is about 5 K near the occurrence of knocking.

A portable remote methane sensor using a 1.65 µm InGaAsP distributed-feedback laser is developed. It is designed as a man-portable long-path absorption lidar using a topographical target with a range of up to about 10 m. An operator can search for gas leaks easily by scanning the laser light. High sensitivity is accomplished by means of second-harmonic detection using frequency-modulation spectroscopy. The experimental detection limit (signal-to-noise ratio = 1) with a diffusive target of magnesium oxide (6 m range, normal incidence) is 450 ppb m with a time constant of 100 ms. Measurements of the reflectance of real targets show that the sensor can distinguish small gas leaks (typically 10 cm³ min ^-1) within a range of several metres.

New algorithms for particle-tracking velocimetry are proposed and tested with typical particle images showing two-dimensional fluid flows. There are new ideas not only in the algorithm of the particle tracking itself but also in that of the individual-particle detection. The performance of the particle tracking is much improved by the new relaxation method and that of the individual-particle detection by the use of the dynamic threshold-binarization method. The special concern of the authors about the new algorithms is the applicability of particle-tracking velocimetry to high-density particle images, contrary to what is usually believed regarding this type of particle-imaging velocimetry. These new algorithms are first tested in synthetic images with a variety of particle parameters and then in other types of experimental visualizations showing jet and wake flows.

A new particle-image-velocimetry (PIV)-data-processing method called multi-intensity-layer PIV is developed and applied for injector spray analysis. It uses the principle that the light intensity scattered from a small particle is proportional to its diameter squared at a certain angle. The light-intensity information was used to provide diameter information from PIV data. There are two methods of uncertainty analysis: intensity weighted and number-density weighted. The measurement results demonstrated that the droplet dynamics for droplets of various diameters can be described by this multi-intensity-layer PIV, that is, small droplets followed the vortex shearing and highly turbulent flows, whereas larger droplets penetrated the shear flow. It was found that this multi-intensity-layer PIV would be a useful method for describing spatial droplet-spray behaviour in a practical spray diagnostic.

Temporal variations of a two-dimensional distribution of velocities in a nitrogen jet and a methane-jet flame are measured by cross-correlation particle-image velocimetry (PIV). Two different approaches to investigating the turbulence characteristics are demonstrated. One gives the distribution of ensemble-averaged velocities and turbulence intensities by means of repetitive PIV measurements using a double-pulse laser for a longer period. The other provides the detailed motion of velocity profiles for a shorter duration, allowing one to analyse the characteristic scale of turbulence using a high-power continuous laser.

The accuracy of measurements of the time-averaged velocity and turbulence intensity is quantitatively assessed on the basis of the agreement with the results from hot-wire-anemometry (HWA) measurement. This indicates the feasibility of the PIV measurement, which may supply information about turbulence characteristics. From the measured results for a jet and a jetting flame, it is shown that the velocity gradient in the shear layer in the reacting zone is increased due to the local acceleration caused by buoyancy, resulting in higher turbulence intensities than those in a non-reacting jet.

Also, from the change in the distribution of velocity vectors with time, it is clear that the turbulence eddies are carried downstream along the gas motion with little transformation. The time scale of turbulence at each location in the flow is obtained from the autocorrelation function of the velocity fluctuations. Furthermore, this can afford an estimate of the turbulence length scale if one assumes that the Taylor hypothesis is valid and multiplies the time scale and the time-average velocity. It is shown that the characteristic length scales of a flaming jet are about 1.5 times greater than those of a non-flaming jet. The effects of combustion on the turbulence in a flaming jet are discussed in detail on the basis of these experimental results.

A stereo-imaging technique for the simultaneous measurement of size and velocity of solid/liquid particles in dispersed two-phase flows is developed. Particles are illuminated with back light provided by the two strobe lamps. Double-pulsed strobe flashing is done synchronously with the framing of the CCD camera to achieve the frame-straddling illumination mode for the measurement of particle velocities. Silhouetted particle images are acquired with two black-and-white CCD cameras in stereo configuration. The particle images are analysed with a specially devised procedure, which can faithfully detect the perimeters both of spherical and of non-spherical particle images. The use of stereo imaging permits measurement of all three velocity components and also resolution of the depth-of-field effect in particle sizing, the problem that has been a key subject in the development of accurate particle-sizing techniques based on back lighting. The technique developed here is capable of sizing 10-500µm particles to within ±4µm inaccuracy. The validity of the technique is demonstrated by the measurement of a variety of transparent/opaque and spherical/non-spherical particles falling down a vertical pipe.

A new technique which can quantitatively visualize the spatial distribution of velocity in flows using optical processing of particle tracking velocimetry (PTV) under deformed double exposure has been developed. Tracer particles seeded in the flow are irradiated by a sheet of light from an argon-ion laser under deformed double exposure. Under deformed double exposure, each locus of the particles displaced in the flow visualizes the direction and the magnitude of the velocity. The loci of displaced particles show the spatial distribution of the flow velocity in a single image frame. The image is taken continuously in real time by a CCD camera. The deformed double exposure has been synchronized with the scanning frame of the CCD camera. The spatial distributions of the loci of the particles have been discriminated at certain magnitudes and directions simultaneously and instantaneously by a multiplexed matched spatial filter (MMSF). The MMSF is a holographic filter which can discriminate the shapes of the loci using optical cross-correlation. Cross-correlation of the shapes has been calculated optically and the correlation peaks which are the discriminated signal appear skew-symmetrically relative to the position of the shapes in each discrimination area. Using this technique, the number and the position of loci, i.e. spatial distributions of velocity in the flow, are visualized. The MMSF technique has been tested for synthetic images and experimental images. The synthetic images have the overlapped and deformed loci of particles in flow. The experimental images are loci of the cavity flow with a high Reynolds number. From the results, it has been demonstrated that PTV images which have high density tracer particles and deformed streaks can be measured by this technique.

This paper describes and compares holographic interferometry and stereoscopic PIV as techniques for measuring out-of-plane velocity fields. Most relevant aspects in both techniques are revised. Special attention is paid to the specific problems encountered in confined flows. The presence of walls limiting the flow prevents the use of some optical configurations for the photographic and holographic recordings. Several optical configurations have been analysed. Experiments have been carried out in a small Rayleigh-Bénard convective cell. Results obtained for the out-of-plane component with both techniques are compared and discussed.

The PIV technique is generalized from the viewpoint of the identification problem of a flow field. The process of obtaining a velocity distribution as an image measurement can be considered as a parametrization problem of a dynamical system. In almost all conventional techniques, the velocity is evaluated as the parameters in a dynamical system using a linear model without physics. These methods always give some spurious velocity vectors in the case of shear flow or vortex flow, and in the region where the tracer particles are scarce. A new PIV technique based on physics is proposed. The obtained velocity field satisfies the governing equation of the fluid. It is possible that not only the velocity but also the pressure is measured, using the Navier-Stokes equations for the dynamic model. The results of jet flow, cavity flow and flow around a waving airfoil demonstrate the effectiveness of this method.

Particle tracking velocimetry (PTV) has recently been recognized as quite an effective engineering research tool for understanding multi-dimensional fluid flow structures. There are, however, still a number of unsettled problems in the practical use of PTV, i.e. the lack of generality of the PTV algorithm for various types of flows and the measurement uncertainty with respect to spatial resolution. The authors have developed a generalized PTV algorithm named the velocity gradient tensor (VGT) method in order to accurately track the tracer particles in a flow field with strong local deformation rates. The performance of the VGT method has already been examined for several simple flow fields, such as linear shearing and Taylor-Green vortex flows. In this paper, the applicability of the VGT method for complicated flows, which include a wide dynamic range in wavenumber, is quantitatively examined by simulation of Rankine vortex flows, Karman vortex-shedding flows around a rectangular cylinder and homogeneous turbulent flows, which are numerically solved by using the unsteady Navier-Stokes equations. The results show that the VGT technique, using only two frames to estimate velocity, performs better than does the four-frame PTV technique and has a remarkably higher tracking performance than those of typical conventional PTV algorithms.

Particle-image velocimetry (PIV) offers lots of advantages for studying fluid mechanics. Many PIV techniques and systems have been developed. However, no standard evaluation tool for evaluating the effectiveness and accuracy of the PIV systems has been established. To popularize PIV practically, for each PIV system there should be some means of evaluating the performance. PIV involves two processes, i.e. capturing the image for visualization and the image analysis. In order to evaluate the image analysis, the use of standard images has been proposed. Using these images, anybody can evaluate the effectiveness and accuracy of the PIV image analysis. The standard PIV images can be grouped into three categories, i.e. standard PIV images for two-dimensional, custom-made images with tunable parameters and images for a transient flow. The standard PIV images that we have developed are distributed via the web site http://www.vsj.or.jp/piv as part of a collaboration with the Visualization Society of Japan. They can be applied to investigate the performance of any PIV technique. The standard PIV images that we have developed have already been accessed by more than 3 000 researchers around the world.

The algorithm which takes into account the effect of refraction of sound wave paths for acoustic computer tomography (CT) is developed. Incorporating the algorithm of refraction into ordinary CT algorithms which are based on Fourier transformation is very difficult. In this paper, the least-squares method, which is capable of considering the refraction effect, is employed to reconstruct the two-dimensional temperature distribution. The refraction effect is solved by writing a set of differential equations which is derived from Fermat's theorem and the calculus of variations. It is impossible to carry out refraction analysis and the reconstruction of temperature distribution simultaneously, so the problem is solved using the iteration method. The measurement field is assumed to take the shape of a circle and 16 speakers, also serving as the receivers, are set around it isometrically. The algorithm is checked through computer simulation with various kinds of temperature distributions. It is shown that the present method which takes into account the algorithm of the refraction effect can reconstruct temperature distributions with much greater accuracy than can methods which do not include the refraction effect.

The changes in vortical and turbulent structure in the near field (X / D < 3.0) of jet mixing flow caused by a lobed nozzle were investigated experimentally in the present study. The techniques of planar laser induced fluorescence and particle image velocimetry were used to accomplish flow visualization and velocity field measurements. The experimental results showed that, compared with a circular jet flow, lobed jet mixing flow was found to have a shorter laminar region, a smaller scale of the spanwise Kelvin-Helmholtz vortices, earlier appearance of small scale turbulent structures and a larger region of intensive mixing in the near field of the jet mixing flow. The central line velocity decay of the lobed jet mixing flow was also found to be much faster than that in a conventional circular jet. All these indicated that the lobed nozzle provides better mixing performance than does a conventional circular nozzle.

In this paper, we report results obtained with a time-of-flight ranging/scanning system based on time-correlated single-photon counting. This system uses a pulsed picosecond diode laser and detects the scattered signal from a non-cooperative target surface using a semiconductor single-photon detector. A demonstration system has been constructed and used to examine the depth resolution obtainable as a function of the integrated number of photon returns. The depth resolution has been examined for integrated photon returns varying by five orders of magnitude, both by obtaining experimental measurements and by computer simulation. Depth resolutions of approximately 3 mm were obtained for only ten returned photons. The effect of the background signal, originating either from temporally uncorrelated light signals or from detector noise, has also been examined.

In this paper a compact, portable instrument is presented for the measurement of full chlorophyll fluorescence kinetics of plants at two different wavelengths. The instrument uses a 635 nm laser diode as a light source with variable gain driving that allows excitations at selectable actinic levels. The plant fluorescence is detected, at 690 nm and 735 nm, through a specially mixed three-branch optical fibre bundle. Large scale field monitoring of vegetation is made possible by the utilization of PC/104-form embedded electronics including a low power, IBM PC/386-compatible single board computer (SBC) with non-volatile flash memory. Application of a general purpose SBC and task oriented programming offers in situ data evaluation making process control possible. The capabilities of the instrument were demonstrated in monitoring soil phytoremediation processes.

The experimental apparatus and measurement technique are described for precision absorption measurements in sodium-noble gas mixtures. The absolute absorption coefficient is measured in the wavelength range from 425 nm to 760 nm with ±2% uncertainty and spectral resolution of 0.02 nm. The precision is achieved by using a specially designed absorption cell with an accurately defined absorption path length, low noise CCD detector and double-beam absorption measurement scheme. The experimental set-up and the cell design details are given. Measurements of sodium atomic number density with ±5% uncertainty complement absorption coefficient measurements and allow derivation of the reduced absorption coefficients for certain spectral features. The sodium atomic number density is measured using the anomalous dispersion method. The accuracy of this method is improved by employing a least-squares fit to the interference image recorded with a CCD detector and the details of this technique are given. The measurements are aimed at stringent testing of theoretical calculations and improving the values of molecular parameters used in calculations.

Miniature glass and stainless-steel cells have been made at the Institute of Low Temperature and Structure Research for the realization of the triple point of mercury (T₉₀ = 234.3156 K) to be used for the calibration of capsule-type standard platinum resistance thermometers. This paper gives details on the construction of these cells and some measurement results obtained at the triple point of mercury.

This paper concerns the application of electrical capacitance tomography (ECT) for media of high dielectric permittivity such as water. The performance of an ECT sensor was analysed numerically for a range of dielectric materials (1⩽ε_r⩽80) and geometrical parameters. On the basis of numerical simulations an ECT sensor with internal electrodes was built. Experimental results concerned with imaging air voids in distilled water and water-continuous dispersions of oil, using a commercially available PTL tomography system, are presented. Effects arising from the conductivity of water are studied and prospects of using the ECT system in an `electrical resistivity' mode for weakly conductive solutions are outlined.

A contactless method for three-dimensional velocity reconstruction in electrically conducting fluids is presented. The method is based on the fact that an additional magnetic field is induced if the moving fluid is exposed to a primary magnetic field. By applying the primary magnetic field successively in two different directions and measuring the corresponding induced magnetic fields, the fluid velocity can be reconstructed if some kind of regularization of the velocity field is used. For a conducting fluid in a sphere, analytical expressions for the connection between spherical harmonics expansion coefficients of the induced magnetic fields on one side and of the defining scalars of the velocity on the other side are derived. For other geometries a general method for numerical inversion is proposed.

A thermoelastic method for measuring the thermal diffusivities of elastic solids has recently been presented. The accuracy for the most conductive metals is not satisfactory. The cause is traced to thermal contact resistance; a new procedure to calibrate for contact resistance and to take it into account in data analysis is devised. The new measurement procedure is validated by tests performed at room temperature on various metallic reference materials, obtaining precision and accuracy comparable to those of established methods, also for short specimens and for the higher diffusivity metals.

The objective of this article is to present a methodology for the evaluation of uncertainties in the results of calibration by comparison, based on the implementation of the concept of traceability and on the use of weighted least squares fitting. The general case, where the measuring equipment is tested against a standard of higher metrological quality at several points on a range, is considered. The proposed methodology deals with not only the experimental data in each calibration point but also their quality. The fact that both the outputs of the reference standard and the indications of the device under calibration are characterized by their own uncertainty is also taken into account. In this way calibration leads not only to determination of the coefficients of the calibration curve, but also to estimation of their uncertainties. This is particularly useful when a statement of uncertainty which concerns a range of values rather than a single result is required.

Scattering ellipsometry is a measurement technique that can extract the characteristics of particles with relative ease. For some while, we have been interested in the use of scattering ellipsometry to examine the particles in the anterior chamber of the human eye. These particles are globular proteins, typically some 6 or 7 nm in diameter and measurements conducted at a wavelength of 670 nm confirm this. Particles or particle aggregates much greater in size will give rise to characteristic patterns in the ellipsometric results and analysis of these patterns could lead to a complete description of the physical properties of such particles. Examples of measurements of this nature made on latex particles are included. The results obtained from the measurements described confirm that bovine serum albumin is suitable as a calibrant for a scattering ellipsometer.

A general, analytical closed-form solution for laser-induced thermal acoustic (LITA) signals using homodyne or heterodyne detection and using electrostrictive and thermal gratings is derived. A one-hidden-layer feed-forward neural network is trained using back-propagation learning and a steepest descent learning rule to extract the speed of sound and flow velocity from a heterodyne LITA signal. The effect of the network size on the performance is demonstrated. The accuracy is determined with a second set of LITA signals that were not used during the training phase. The accuracy is found to be better than that of a conventional frequency decomposition technique while being computationally as efficient. This data analysis method is robust with respect to noise, numerically stable and fast enough for real-time data analysis.

We previously proposed a differential type inverse problem in which, if no source exists in the region of interest, the spatial distribution of the relative value of a physical parameter can be determined solely from measured distributions of another physical variable in that region. In real-world applications, however, the problem inevitably becomes an ill-posed one due to measurement noise making it impossible to guarantee the existence of a stable and unique target global distribution. Here, we cope with this problematic condition by using a robust numerically based implicit-integration approach that incorporates in a novel way a computationally efficient regularization method using low-pass filtered spectra derived from field measurements. As an example, the approach is applied to solve the conductivity determination problem using current density field measurements. The effectiveness of this method is evaluated by reconstructing a globally relative conductivity distribution using simulated noise-filled measurement data. The resultant reconstructions indicate that the approach provides a practical means for robustly solving the differential type inverse problem considered.

In this paper we report on the fabrication of an affinity biochip with a matrix of 900 targets for detection with imaging ellipsometry. Two methods of fabrication of chips are shown: one based on wet etching of a silicon surface and the other on the preparation of so-called tension wells on the silicon surface. The dispensing of reagents and ligands was performed using a pipetting robot equipped with a micro-capillary, a syringe pump and micro-stepping motors. Measurements were performed on the chips in real time with carbohydrate model substances selected for six common lectins. Affinity binding was shown for three of the tested model substances.

In particle image velocimetry experiments where optical access is limited or in microscale geometries, it may be desirable to illuminate the entire test section with a volume of light, as opposed to a two-dimensional sheet of light. With volume illumination, the depth of the measurement plane must be defined by the focusing characteristics of the recording optics. A theoretical expression for the depth of the two-dimensional measurement plane is derived and it is shown to agree well with experimental observations. Unfocused particle images, which lie outside the measurement plane, create background noise that decreases the signal-to-noise ratio of the particle-image fields. Results show that the particle concentration must be chosen judiciously in order to balance the desired spatial resolution and signal-to-noise ratio of the particle-image field.

The forward characteristics of a cryogenic GaAlAs temperature sensor diode (Lake Shore Cryotronics, Inc) in the temperature range 10-300 K and for fixed currents between 10 nA and 500 µA have been presented. The upturn in the forward characteristic below 35 K was found to be shifted to lower temperatures on reducing the current. The sensitivity at low temperature was found to reduce with current (I ) according to a power law. The sensitivity at high temperature was found to increase linearly with decreasing log (I ). We suggest the use of a current of less than 10 µA, which has the advantage of reducing Joule power dissipation and improving high temperature sensitivity and linearity.

Realization of the phase equilibrium method for very low frost-point temperature generation of a humid gas is presented. A theoretical approach to the analysis of thermodynamic processes of the phase equilibrium achievement is suggested. On the basis of theoretical and experimental analyses, preliminary and main saturators, as parts of the standard low frost-point humidity generator, are designed, enabling us to generate down to -100 °C of frost-point temperature.

By measuring the ratio of p- to s-polarized light intensities reflected at an angle of incidence of 45° from a transparent solid, the refractive index of that solid can be determined. The critical factors affecting the accuracy of the refractive index measurement using this technique are discussed. The extension of this technique to materials which are weakly absorbing, or that have non-ideal surfaces, is also discussed and the errors that arise from the neglect of these effects are quantified.

Two novel methods for surface profile extraction based on multiple ultrasonic range measurements are described and compared. One of the methods employs morphological processing techniques, whereas the other employs a spatial voting scheme followed by simple thresholding. Morphological processing exploits neighbouring relationships between the pixels of the generated arc map. On the other hand, spatial voting relies on the number of votes accumulated in each pixel and ignores neighbouring relationships. Both approaches are extremely flexible and robust, in addition to being simple and straightforward. They can deal with arbitrary numbers and configurations of sensors as well as synthetic arrays. The methods have the intrinsic ability to suppress spurious readings, crosstalk and higher-order reflections, and process multiple reflections informatively. The performances of the two methods are compared on various examples involving both simulated and experimental data. The morphological processing method outperforms the spatial voting method in most cases with errors reduced by up to 80%. The effect of varying the measurement noise and surface roughness is also considered. Morphological processing is observed to be superior to spatial voting under these conditions as well.

The quality of the optical surface of commercial paper after laser printing was investigated using a sensor based on a diffractive element. Using a new sensor set-up, it was possible to gain image information about reflection and transmission of light, at normal light incidence, from paper simultaneously. These two parameters were measured before and after laser printing. Image data revealed information about the gloss and surface roughness of paper as well as the influence of the black ink used in printing.

Entries marked by * appear here for the first time.

2000

July

* 3 - 5: IMCS 2000 8th International Meeting on Chemical Sensors, Basel, Switzerland Details: http://www.elsevier.nl/locate/imcs2000

* 4 - 7: QSA-11 International Millenium Conference on Quantitative Surface Analysis, Guildford, UK Details: P Briggs, email p.briggs@surrey.ac.uk

10 - 13: 10th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal Details: Graça Pereira, Mechanical Engineering Department, Instituto Superior Técnico, 1049-001 Lisboa, Portugal. Fax +351 1 849 6156, email llaser@dem.ist.utl.pt, http://in3.dem.ist.utl.pt/lisboa-laser

* 16 - 20: National Conference of Standards Laboratories Workshop and Symposium, Toronto, Canada Details: telephone +1 303 440 3339, fax +1 303 440 3384, email ncsl-staff@ncsl-hq.org, http://www.ncsl-hq.org

* 19 - 20: EUSPEN International Seminar on Precision Engineering and Micro-Technology, Aachen, Germany Details: Fraunhofer IPT, M Weck, Steinbachstrasse 17, 52074 Aachen, Germany. Telephone +49 (0) 2 41/89 04 112, fax +49 (0) 2 41/89 04 198, email zpm@ipt.fhg.de, http://www.ipt.fhg.de/zpm

* 19 - 21: European Conference on Magnetic Sensors and Actuators, Dresden, Germany Details: EMSA 2000, IFW Dresden, PO Box 270016, D-01171, Dresden, Germany. Telephone +49 351 4659 670, fax +49 351 4659 745, email emsa2000@ifw-dresden.de

August

27 - 30: Eurosensors XIV 14th European Conference on Solid State Transducers, Copenhagen, Denmark Details: fax +45 3314 5750, email eurosensors@vanhauen.dk,http//:www.eurosensors.dk

September

25 - 28: IMEKO 2000 International Measurement Confederation XVI IMEKO World Congress, Vienna, Austria Details: http://www.imeko2000.at/main.htm

* 26 - 28: Symposium on Optical Fiber Measurements, Boulder, Colorado Details: Wendy Ortega Henderson, National Institute of Standards and Technology (346.16), 325 Broadway, CO 80303, USA. Email ortegaw@boulder.nist.gov, http://www.boulder.nist.gov/blconf.htm

* 28 September - 4 October: International Conference on Optical Holography and its Applications, Kiev, Ukraine Details: SPIE/Ukraine, 45 Prospect Nauki, Kiev 252028, Ukraine. Telephone +380 44 265 62 05, fax +380 44 265 54 30, emailholoapl@isp.kiev.ua

October

11 - 13: OFS 2000 14th International Conference on Optical Fibre Sensors, Venice, Italy Details: OFS 2000, Instituto Internazionale delle Comunicazioni, Villa Piaggio, Via Pertinace, I-16125 Genova, Italy. Telephone +39 010 2722 383, fax +39 010 2722 183, email iic.istcomge@interbusiness.it, http://service2.area.fi.cnr.it/ofs2000/home.htm

December

* 4 - 8: International Conference on Lasers 2000, Albuquerque, New Mexico Details: telephone +1 703 642 5835, fax +1 703 642 5838

2001

May

* 28 May - 1 June: EUSPEN 2nd International Conference, Turin, Italy Details: fax +39 011 669 23 68, email torino2001@euspen.org,http://www.euspen.org/torino2001