Betrouwbaar meten aan LED verlichting

Paul Dekkerpdekker@vsl.nl

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- Introductie VSL;

- Herleidbaarheid en metrologie;

- Led metingen bij VSL.

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pdekker@vsl.nl

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IntroductieVSL

pdekker@vsl.nl

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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.

pdekker@vsl.nl

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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

pdekker@vsl.nl

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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

pdekker@vsl.nl

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Enabling measurements

pdekker@vsl.nl

Trade

Science

Industry

Society

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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

pdekker@vsl.nl

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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

pdekker@vsl.nl

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Traceable MetrologySI, traceability, uncertainty and

international infrastructure

pdekker@vsl.nl

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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

pdekker@vsl.nl

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The SI system of units

- Seven base units- Derived units formed by

multiplication and division, without numerical prefactors

- Decimal multipliers

pdekker@vsl.nl

m

kg

K

As mol

cd

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Getting the units wrong…

pdekker@vsl.nl

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.”

Air Canada Flight 143 – Gimli Glider

• 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.”

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Traceability

- Traceability: a measurement result is linked to the definition of the unit

- by an unbroken series of comparisons

- each with a specified uncertainty

- Traceable measurements are absolute: independent of instrument and method

pdekker@vsl.nl

Incr

easi

ng u

ncer

tain

ty

Transfer detectoren

Premiere standaard

Illuminantiemeter

Verlichting op werkplek

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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

pdekker@vsl.nl

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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

pdekker@vsl.nl

Euromet.L-K2 150 mm gauge block

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Radiometrie en Fotometrie bij VSL

pdekker@vsl.nl

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• 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).

Optica: radiometrie en fotometrie

d)()(emv VK

lm/W683m K

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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)

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Faciliteiten en Herleidbaarheid

Spectrale irradiantie faciliteit

RAD3D 3 m bol

Absolute cryogene radiometer

Fotometriebank

Rigo goniometerpdekker@vsl.nl

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Optical: Goniometer

-Spatial resolved irradiance and illuminance distribution of any given light source using photometers and a array spectroradiometer

Theoretical highest achievable accuracy in:

− lumen CCT CRI xy Duv− Efficacy (lm/W)

21 pdekker@vsl.nl

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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.

22 pdekker@vsl.nl

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Power measements

DZhao@vsl.nl23

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. Dzhao@vsl.nl

Choose correct wiring method

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ACPower supply

VA

Power meter

When the measured current is relatively large

When the measured current is relatively small

ACPower supply

AV

Power meter

resistance small

resistance large

Pag. 25pdekker@vsl.nl