Transcript VSL
Betrouwbaar meten aan LED verlichting Paul Dekker [email protected] - Introductie VSL; - Herleidbaarheid en metrologie; - Led metingen bij VSL. [email protected] Pag. P2 Introductie VSL [email protected] Pag. P3 VSL - VSL is the National Metrology Institute of the Netherlands, appointed by the Dutch government to maintain and develop the national measurement standards. - VSL makes measurement results of companies, laboratories and organizations directly traceable to international standards. - VSL makes an important contribution towards the reliability, quality and innovation of products and processes, both in business and society at large. [email protected] Pag. P4 The national metrology instute - Maintaining the Dutch national standards (kilogram, meter, second,…) - Developing new and improved standards (SSL, nanometrology, LNG,…) - Providing the highest possible measurement accuracy in the Netherlands - Linking the Netherlands to the international metrological infrastructure [email protected] Pag. P5 Technical fields - Chemistry: gas composition, biofuels Electricity: DC, AC, HF, high-voltage power Flow: gas, oil, LNG Ionizing radiation Length: optical frequency standards, classical geometrical measurements, micro/nanometrology Mass and related quantities Optics: photometry/radiometry, radiation thermometry Temperature and humidity Time and frequency [email protected] Pag. P6 Enabling measurements [email protected] Pag. P7 Trade Industry Science Society VSL services - High-accuracy calibration of standards and instruments - Supply of certified reference materials - Performance analysis and validation of measurement systems - Consultancy and contract research - Proficiency testing - Training courses [email protected] Pag. P8 VSL facts and figures - Private company with a public task Shareholder: TNO Bedrijven Turnover: partly government, partly market About 100 FTE (40% PhD/MSc, 40% BSc) - Located in Delft - ISO 17025 accredited [email protected] Pag. P9 Traceable Metrology SI, traceability, uncertainty and international infrastructure [email protected] Pag. P 10 Reliability of measurements Measurement result = numerical value × unit Reliability implies: - The unit is well-defined and the same for all - The spread of possible numerical values is quantified into a known uncertainty - The uncertainty is small enough for the given application [email protected] Pag. P 11 The SI system of units - Seven base units - Derived units formed by multiplication and division, without numerical prefactors - Decimal multipliers [email protected] Pag. P 12 Getting the units wrong… Air Canada Flight 143 – Gimli Glider NASA Mars Climate Orbiter - Crashes 23rd September 1999 (125 M$). - “The navigation error arose because a NASA subcontractor (Lockheed Martin) used Imperial units (pound-seconds) instead of the metric units (newton-seconds) as specified by NASA.” [email protected] Pag. P 13 • Boeing 767 from Ottawa to Edmonton gets into trouble because of fuel shortage. • “Instead of 22,300 kg of fuel, they had 22,300 pounds on board — only a little over 10,000 kg, or less than half the amount required to reach their destination.” Traceability Increasing uncertainty - Traceability: a measurement result is linked to the definition of the unit Premiere standaard Transfer detectoren Illuminantiemeter Verlichting op werkplek [email protected] Pag. P 14 - by an unbroken series of comparisons - each with a specified uncertainty - Traceable measurements are absolute: independent of instrument and method Knowing the uncertainty - Knowing the uncertainty is a must: - Choosing the right measurement solution Comparing measurement results Making pass/fail decisions in tests Attaching significance to observations Applying appropriate safety margins - Underestimation can lead to wrong decisions, with possible dramatic consequences - Overestimation can lead to unnecessary efforts and expenditure [email protected] Pag. P 15 CIPM MRA - Mutual Recognition Arrangement (MRA): countries recognize measurement capabilities of other NMIs Online database of Calibration and Measurement Capabilities (CMCs): kcdb.bipm.org Periodic validation by key comparisons VSL currently has 849 individual CMCs Euromet.L-K2 150 mm gauge block [email protected] Pag. P 16 Radiometrie en Fotometrie bij VSL [email protected] Pag. P 17 Optica: radiometrie en fotometrie • Radiometrie : meting van de hoeveelheid optische straling (vermogen) in UV, VIS, IR • Fotometrie : meting van het visuele effect van optische straling, zoals waargenomen door het menselijk oog (380-780nm). v K m e ( ) V ( ) d Km 683 lm/W Pag. 18 [email protected] Kalibratie van bronnen en detectoren • • • • • • • • Spectrale irradiantie (W nm-1 m-2) Lichtsterkte (candela) Lichtstroom (lm) Illuminantie (lm m-2, lx) Radiant flux (W) Kleurparameters (X,Y,Z, CCT) Spectrale responsiviteit (A nm-1 W-1) Illuminantie responsiviteit (A lx-1) Pag. 19 [email protected] Faciliteiten en Herleidbaarheid Spectrale irradiantie faciliteit Fotometriebank Absolute cryogene radiometer RAD3D 3 m bol Pag. 20 [email protected] Rigo goniometer Optical: Goniometer -Spatial resolved irradiance and illuminance distribution of any given light source using photometers and a array spectroradiometer Theoretical highest achievable accuracy in: − − Pag. 21 [email protected] lumen CCT Efficacy (lm/W) CRI xy Duv Optical: Integrating sphere Problems: - Colour mismatch of photometers introduces errors - Different shapes need different corrections - Different (beam) profiles need different corrections Solution: - Combination of photometer and spectroradiometer - Fully characterization of sphere is needed in terms of spatial uniformity (reflection) and spectral reflections - Colour properties (CCT, CRI, xy and Duv) always based on spectral flux. Pag. 22 [email protected] Power measements Use normal mode for rms measurements Check the wiring Sync to voltage instead of current Enable frequency filter Disable line filter Keep the cable short Use devices with enough bandwidth Use a power supply with low THD More stringent conditions for stabilization (e.g. temperature) Use a small shunt resistor Pag. 23 [email protected] Choose correct wiring method Power meter Power meter A V V resistance small AC Power supply A resistance large AC Power supply When the measured current is relatively large Pag. 24 [email protected] When the measured current is relatively small [email protected] Pag. 25