A*STAR Seminar on LED and Solid State Lighting. Standards and Technologies. Measurements. 05 August LIU Yuanjie National Metrology Centre

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1 A*STAR Seminar on LED and Solid State Lighting Standards and Technologies available at NMC for LED Measurements 05 August 2011 LIU Yuanjie National Metrology Centre

2 Outline NMC overview Basic optical quantities commonly measured for LED/SSL Standards and technologies available at NMC for LED/SSL measurements New capability development

3 Mission: Fostering world-class scientific research and talent for a vibrant knowledge-based Singapore Objectives: Enhance Singapore s industrial competitiveness and strengthen Singapore s R&D capabilities. Chairman Mr Lim Chuan Poh Dy Chairman Prof Tan Chorh Chuan Managing Director Prof Low Teck Seng Managing Director s Office SERC BMRC DSI - Data Storage Institute I 2 R - Institute for Infocomm Research ICES - Institute of Chemical and Engineering Sciences IHPC - Institute of High Performance Computing IME - Institute of Microelectronics IMRE - Institute of Materials Research & Engineering NMC - National Metrology Centre SIMTech - Singapore Institute of Manufacturing Technology A*STAR Graduate Academy A*STAR Joint Council Corporate Group BII - Bioinformatics Institute GIS - Genome Institute of Singapore IBN - Institute of Bioengineering & Nanotechnology IMCB - Institute of Molecular and Cell Biology BTI - Bioprocessing Technology Institute IMB - Institute of Medical Biology SICS - Singapore Institute for Clinical Sciences 3

4 NMC Organization Executive Director Dr Lee Loke Chong Dy Director Dr Chua Sze Wey Research and Development Unit Head: Dr Tung Siew Kong Standards and Infrastructure Unit Head: Victor Tan Industry Development Office Director: James Ling Electrical Metrology Head Dr Chua Sze Wey Mechanical Metrology Head Chua Hock Ann Optical Metrology Head Ms Tan Siew Leng Administration Head Ms Leow Guat Hiong Functions Technology Development Industry Services Custodian of Metrology Standards Staff Milestones Laboratories International Linkages

5 Metrology Standards Custodian Primary Level Secondary Level Working Level

6 NMC Laboratories Electrical Metrology (EM) Mechanical Metrology (MM) Optical Metrology (OM) Electrical RF & Microwave Acoustics & Vibration Gas Mass & Force Pressure & Flow Temperature & Humidity Length & Dimensional Optical Radiation Time & Frequency

7 Participation of NMC in Global Metrology Mutual Recognition Arrangement (MRA) Initiated in 1999 for mutual recognition of national measurement standards and calibration & measurement certificates issued by national metrology institutes (79 signatories) To provide technical basis for wider agreements negotiated for international trade. NMC signed the MRA in 1999 under the Metre Convention framework. NMC participates in international & regional comparisons to verify capabilities. International recognition of Singapore s national metrology infrastructure. MRA certificates signed on 14 Oct 1999

8 NMC measurement capabilities recognised worldwide

9 Basic optical quantities [Spectral] Radiant intensity (W.sr -1) / Luminous intensity (candela, or lm.sr -1 ) [Spectral] Radiant flux (W) / Luminous flux (lumen) [Spectral] Irradiance (W.m -2 ) / Illuminance (lux, or lm.m -2 ) [Spectral] Radiance (W.m -2 sr -1 ) / Luminance (cd/m -2 )

10 Photometry versus Radiometry CIE (International Commission on Illumination) introduced V(λ) function in 1924 and V (λ) function in 1931 to describe the relative spectral sensitivity of the average human eye for photopic and scotopic vision.

11 Photometry versus Radiometry The sensitivity of the eye is maximum at 555nm (green) for photopic vision X v = K m 830nm X e, V()d 360nm Where e and v denote radiometric and photometric quantities respectively; X can be any of the following radiometric quantities: intensity, flux, irradiance, or radiance; X e,λ is the spectral density of the radiometric quantity X e ; K m = 683 is the maximum spectral luminous efficacy value at 555 nm.

12 Radiant / Luminous intensity Used to describe the amount of radiation / light leaving a source, at a specified direction Radiant intensity I e, W.sr -1 /Luminous intensity I v, cd (candela, or lm.sr -1 ) I I radiant/luminous flux emitted by a source within a unit solid angle in a specified direction e = d d φ Ω e I v = d d φ Ω 830 nm v = K m I e, λ ( λ ) V ( λ ) 360 nm v S dλ dω dφ

13 Setup for intensity measurement Standard lamp Standard illuminance (lux) meter NMC photometric bench, 8 m long

14 Averaged LED intensity measurement Standard lamp CIE standard condition A: d = 316 mm ( Ω = sr) CIE standard condition B: d = 100 mm ( Ω = 0.01 sr)

15 Total Radiant / Luminous Flux dω r da dω = da/r 2 Total area of the sphere: 4 r 2 Total solid angle: 4 φ e = I dω, φ = I dω, Ω e Total Radiant flux (W) / Luminous flux (lm) of a source: can be calculated from the distribution of radiant / luminous intensity over the whole 4 solid angle which can be measured by a goniophotometer or an integrating sphere v Ω v

16 LED/SSL total flux measurement Total Radiant flux (W) / Luminous flux (lm) can be measured in two geometries: whole 4 solid angle or 2 solid angle (forward flux) in an integrating sphere

17 LED/SSL total flux measurement Forward flux (2) measureemnt 1-meter integrating sphere Flux standard lamp Single LED LED Lamps Spectroradiometer

18 LED/SSL total flux measurement Sphere scanner to measure and correct for spatial non-uniformity

19 Irradiance / Illuminance The radiant flux / light that is incident on a surface per unit area of that surface. E e = dφ e / da, (W m -2 ), E v = dφ v / da, (lx, lm m -2 ) where dφ is the element of incident flux and dλ and da are the elements of wavelength and area respectively dφ Surface of receiver da

20 Irradiance / Illuminance measurement E = I / d 2 where d is the distance between lamp and photometer Standard lamp Standard illuminance (lux) meter NMC photometric bench, 8 m long

21 Other optical quantities Chromaticity coordinates (colour) Colour rendering index (CRI) Correlated colour temperature (CCT) These colour related quantities can be calculated from spectral data and colour matching functions: Spectral radiant intensity(w.sr -1 nm -1 ) Spectral radiant flux (W.nm -1 ) Spectral Irradiance (W.m -2 nm -1 )

22 Radiance / Luminance New capability development funded by A*STAR The radiant flux that is leaving a surface of a light source per unit projected area of the source and per unit solid angle. L e = d 2 Φ e / (da cosθ dω), (W m -2 sr -1 ) L v = d 2 Φ v / (da cosθ dω), (cd m -2 ) where d 2 Φ is the element of emitted flux, da cosθ and dω are the elements of wavelength, projected area of the light source and solid angle respectively. da Surfac e of source da cosθ θ dω dφ

23 LED Radiance/luminance (Brightness) Measurement Spectroradiometer for spectral radiance measurement Spectral radiance measurement Is needed for photobiological safety assessment of LED/SSL

24 Spectral Radiance calibration facility

25 LED/SSL Total flux / Intensity distribution measurement using goniometer Measurement system under development

26 Thank You!