IMEKO Event Proceedings Search

   

Page 394 of 977 Results 3931 - 3940 of 9762

Marek Dobosz
INTERFERENCE METHOD FOR ULTRA-PRECISION MEASUREMENT OF ANGULAR MICRO-DEFLECTION

A new interferometric method for ultra-precise measurement of laser beam angular deflection is presented. Also angular tilt of measuring device in relation to the beam axis can be measured. The method is based on interference fringe period analysis in the selected plane of measurement. We proof that if the number of beam reflections in the interferometer arms differs by an odd number, then the deflection of the input beam can be measured by evaluating the change of the observed interference fringe period.
The theoretical basis and experimental verification of the method are presented. Two interferometer designs are compared. Influence of the wavelength change and the lateral shifts of the beam axis on laser beam deflection measurement are analyzed. Resolution reaching single nanoradians (0,001 arcsec) is shown. The main feature of the proposed method is that the applied interference system can be very small (having a volume of approximately 1 cm³). Design of the sensor can be extremely robust, and insensitive to the most common disturbances (like temperature, linear displacements etc.). Because of these feature, the system can be applied easily in laser design as a system for output beam angular stabilization. Also angular deflection of the interferometer set-up in relation to the input beam axis can be measured.

Masato Aketagawa, Mumummad Madden, Eiki Okuyama
CONCURRENT MEASUREMENT OF SPINDLE RADIAL, AXIAL AND ANGULAR MOTIONS USING CONCENTRIC CIRCLE GRATING AND PHASE MODULATION INTERFEROMETERS

This paper describes a concurrent measurement of spindle radial, axial and angular motions using concentric circle grating and phase modulation interferometers. In the measurement, the concentric circle grating with fine pitch is a reference artifact. A frequency modulated laser diode is used for the light source of the phase modulation interferometers. The phase modulation interferometers, which consist of three Michelson and three grating interferometers, measure three radial and three axial displacements of the grating. From these six measured displacements, radial, axial and angular motions of the spindle can be determined concurrently. In the paper, a measurement principle, a measurement instrument and experimental results are discussed. Concurrent measurements of spindle radial, axial and angular motions were successfully attained.

Youichi Bitou, Yohan Kondo
DEFLECTOMETRIC PROFILER WITH SMALL BEAM SIZE USING A COMMERCIALLY AVAILABLE AUTOCOLLIMATOR

The special resolution of the angle-based deflectometric surface profiler has been improved by introducing a novel null instrument. Proposed null instrument is simple, inexpensive, and has fast response time. High accuracy flatness measurement for low reflective surface has been successfully demonstrated with 1 mm laser beam spot size. The repeatability of the surface form measurement is better than ±0.6 nm.

Ralf D. Geckeler, Michael Krause, Andreas Just, Oliver Kranz, Harald Bosse
NEW FRONTIERS IN ANGLE METROLOGY AT THE PTB

An overview of the current status of angle metrology at the Physikalisch-Technische Bundesanstalt (PTB), the National Metrology Institute of Germany, is provided. Current and future challenges to angle metrology are described. Novel developments at the PTB are outlined. Our research programme is currently strongly influenced by the European Metrology Research Programme (EMRP) SIB 58 Angle Metrology project. We present our novel selfcalibration method for the fast and precise in-situ calibration of angle encoders without recourse to external reference standards which relies on a suitable geometric arrangement of multiple heads which read out the radial grating of the encoder at different angular positions. Additional progress has been achieved in this field by adapting an advanced error-separating shearing technique to angle metrology and by testing it experimentally. This technique, by applying defined angle offsets between two angle measuring devices, offers a unique opportunity to cross-calibrate both devices. We also present progress in the development of a novel concept and of a device for the precise and traceable calibration of spatial angles, the Spatial Angle Autocollimator Calibrator (SAAC). We report on the status of the first European Association of National Metrology Institutes (EURAMET) Key Comparison on autocollimator calibration (EURAMET.L-K3.2009).

L. Blunt, L. Fleming, M. Elrawemi, D. Robbins, H. Muhamedsalih
IN-LINE METROLOGY FOR DEFECT ASSESSMENT ON LARGE AREA ROLL TO ROLL SUBSTRATES

This paper reports on work carried out as part of the EU funded research project “Nanomend”. The project seeks to develop integrated process inspection, cleaning, repair for nano-scale thin films on large area substrates. In order to prevent water ingress into flexible PV modules they are coated with a protective barrier layer of Al2O3 using atomic layer deposition (ALD) techniques. Unfortunately defects in this layer have been shown to reduce module efficiency over a period of time due to water vapour ingress. The present work concentrates on defect detection and reports on the use of areal surface metrology to correlate defect morphology with water vapour transmission rate (WVTR) through the protective barrier coatings. The use of advanced segmentation techniques is demonstrated where topographic information on functionally significant defects can be extracted and quantified. The work also reports on the deployment of new in line interferometric optical sensors designed to measure and catalogue the defect distribution and size where they are present in the barrier film. The sensors have built-in environmental vibration compensation and are being deployed on a demonstrator system at a Roll2Roll production facility in the UK.

G. B. Rossi, F. Crenna
Probabilistic Uncertainty Evaluation Aiding Critical Measurement-Based Decision

Measurements are often an objective support for decision-making. If a measurement result can affect the decision, the measurement uncertainty associated with the result can be useful to manage the risk of a wrong decision. This is applicable to measurements in all fields, scientific, industrial or human-related. In the last case particular care has to be taken when a wrong decision can affect health, life or environment.
Now, measurement-based decisions may be, with fair generality, reduced to a conformity assessment problem. Typically the state of the process under investigation is monitored by a set of measured parameters and their belonging to a given “safe” subset of the parameter space has to be checked.
Decisions are thus strongly affected by measurement uncertainty. Common decision rules are based on expressing measurement uncertainty as intervals of values (expanded uncertainty), which results in an on-off criterion, with an uncertainty region. Due to the importance of the problem, a more sophisticated approach, based on probability, merits investigation, aiming at improving the quantification of the risk associated with each decision. In the article, such an approach is addressed in general terms. The role of uncertainty evaluation is then discussed and an algorithm for evaluating uncertainty in terms of probability density is presented and the advantages of this approach are discussed.

Zygmunt L. Warsza
Bridges Supplied by Two Current Sources - New Tool for Impedance Measurements and Signal Conditioning

A new type of measuring circuitry is presented. It is an impedance bridge unconventionally supplied by two current sources connected in parallel to opposite arms of the bridge. This circuit has two independent balance states, when voltage on each output -? bridge diagonals ?- equals zero. If two current sources are ideal and identical, the equality of impedance products of neighboring arms of the output diagonal are the balance conditions. These two relations are different from the one of the classic Wheastone bridge. The author proposes to call this new type of circuits as: double current bridge .
Formulas for currents, voltages and powers of the bridge arms in balance conditions are given. Sensitivities of such circuits and their optimization have been discussed. The method of measurements when current sources are not identical is also proposed. Expressions for output voltages of unbalanced circuit are given. The possibility of simultaneous measurement of two variables by a pair of sensors and measurements of increments of every sensor without disconnecting the bridge are also presented. Some conclusions and directions of future developments in this area are also included.

Jorge A. Valeriano, Felipe R. Lara, Norma R. Chavez
Development of a Design Methodology for Digital Measurement Instrumentation Using Complex Programmable Logic Device

In this work, we present the development of a methodology that is a practical guide for the design and implementation of digital measurement instruments, using Programmable Logic Devices (PLD's). Now days the programmable logic technology is a real alternative in the design of a digital systems. This is because of the growing complexity, variable specifications in the development cycle, shorter development time, and the necessity of lower costs. Additionally there are some requirements like confiability and testability. The general goal is to have a universal solution. Objectives of this methodology are: first, reduce time since the problem definition until the manufacturing of the final product; second, define the best use of hardware description language (HDL) to describe behavior.

V. R. Singh
A Novel Smart Silicon Sensor for the Characterisation of Electro-Medical Lithotripters

High power acoustic lithotripters, like ESWL (Extra-Corporeal Shock Wave Lithotripters), are currently in routine use in the hospitals for the removal of kidney stones, non-invasively and non-destructively. However, proper standardisation of such systems is still required for better safety purpose, and for better health care. Acoustic power output or intensity level of the lithotripter transducer is, generally, measured by using conventional devices like PVDF (polyvinyl-di-fluoride) hydrophones which have their limitation of sensitivity, stability and durability. In order to overcome such problems, a new smart silicon sensor is developed, in the present work, to characterise and calibrate the acoustic or electro-magnetic lithotripters for their output parameters like ultrasonic power output and/ or intensity level to enable the doctors to use the lithotripters in a more effective manner, with proper dosage level, for a particular treatment. with better safety. The semiconductor lithotripsy sensor chip has a four-arm Wheatstone bridge of silicon strain gauges with the associated electronic circuits of signal conditioning and amplifier etc. on the same chip, to make it smart in nature.

Lyubomyr Petryshyn, Grzegorz Pedrak
Effective Analysis and Elaboration of Competitive Methods for Generating LPL for A/D Conversion

On base of analysis rules theoretical and comparisons of effectivity methods of conversion analog-digital (in shortening AD), one qualified spheres most effective uses compared methods, especially for utilizations of method Monte-Carlo, one passed estimation techniques-economics characterizations conversions systems AD Monte-Carlo in aim of enlargement exactitude and speeds of conversions and processing signals. One executed analysis different methods of generating RN and passed analysis methods estimation of quality of fate schedules RN. One gave estimated estimation and results of comparison taking into account methods of estimation quality of fate schedules RN. In recapitulation one formulated conclusions and one qualified sphere most effective uses of method conversion AD Monte-Carlo.

Page 394 of 977 Results 3931 - 3940 of 9762