cie 84 89 i 9006l45 0003935jnhb.fszjzx.com/upload/biaozhun/pdf/cie84y1989.pdf · 2012. 10. 16. ·...

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CIE 84 89 I 9006L45 0003935 T20

ISBN 3 900 734 21 6

COMMISSION INTERNATIONALE DE L’ÉCLAIR/ INTERNATIONAL COMMISSION ON ILLUMINAT 1 NTERNATIONALE BELEUCHTUNGSKOM M ISS

THE MEASUREMENT OF LUMINOUS FLUX

Pub. No CIE 84

iG E ON ON

1 st Edition 1989 UDC: 535.241.41 Descriptors: Luminous flux

535.241.62 Ulbricht sphere 628.981 Evaluation of light source 681.786.3 Goniometer

COPYRIGHT International Commission on IlluminationLicensed by Information Handling ServicesCOPYRIGHT International Commission on IlluminationLicensed by Information Handling Services

CIE 84 89 m 900bL45 000393b 967 m

This réchnical Report has been prepared by C I E Technical Committee 2-02 o f D i v i s i o n 2 'Physical Measurement o f L i g h t and Radiat ion ' and has been approved by t h e Council of t h e Commission I n t e r n a t i o n a l e de 1 'Ec la i rage f o r study and a p p l i c a t i o n . The document r e p o r t s on c u r r e n t knowledge and experience w i t h i n t h e s p e c i f i c f i e l d o f l i g h t and l i g h t i n g described, and i s intended t o be used by t h e C I E membership and other i n t e r e s t e d p a r t i e s . I t should be noted, however, t h a t t h e s ta tus o f t h i s document i s adv isory and no t mandatory. The l a t e s C I E Proceedings, o r p u b l i c a t i o n l i s t i n g s should be consul ted regard ing poss ib le subsequent amendments.

C I E News,

Ce rappor t technique a é t é préparé par l e Comité Technique C I E 2-02 de l a D i v i s i o n 2 'Mesures physiques de l a lumière e t des r a d i a t i o n s ' e t a é t é ap- prouvé par l e Conseil de l a Commission I n t e r n a t i o n a l e de l ' E c l a i r a g e , pour étude e t app l i ca t ion . Le document t r a i t e des connaissances courantes e t de 1 'expér ience dans l e domaine spéc i f ique ind iqué de l a lumière e t de l ' é c l a i r a g e , e t il e s t é t a b l i pour l ' usage des membres de l a C I E e t aut res groupements intéressés. I 1 f a u t cependant n o t e r que ce document e s t i n d i c a t i f e t non o b l i g a t o i r e . Pour conna i t re d 'éventuels amendements, consu l te r l e s p l u s récents comptes rendus, C I E News ou l i s t e des p u b l i c a t i o n s de l a C I E .

Dieser Technische B e r i c h t i s t vom C I E Technischen Komitee 2-02 der D i v i s i o n 2 'Phys ika l ische Messung von L i c h t und Strahlung' ausgearbei tet und vom Rat der Commission I n t e r n a t i o n a l e de 1 'Ec la i rage g e b i l l i g t worden. Das Dokument be- r i c h t e t über den d e r z e i t i g e n Stand von Wissen und Erfahrung i n dem behandelten Gebiet von L i c h t und Beleuchtung; es i s t zur Verwendung durch CIE-Mi tg l ieder und durch andere I n t e r e s s i e r t e bestimmt. Es s o l l t e jedoch beachtet werden, daß das Dokument e ine Empfehlung und ke ine V o r s c h r i f t i s t . Die neuesten C I E - Tagungsberichte, das CIE-News oder d i e P u b l i k a t i o n s l i s t e s o l l t e n i m H i n b l i c k auf mögliche spätere Änderungen zu Rate gezogen werden.

Any mention o f organisat ions o r products does no t imply endorsement by t h e C I E . up t o t h e t ime o f going t o press, these may no t be comprehensive.

Whi ls t every care has been taken i n t h e compi la t ion o f any l i s t s ,

Toute mention d'organisme ou de p r o d u i t n ' i m p l i q u e pas une préférence de l a C I E . Malgré l e so in apporté 6 l a compi la t ion de tous l e s documents jusqu 'à l a mise sous presse, ce t r a v a i l ne s a u r a i t ê t r e exhaust i f .

D ie Erwähnung von Organisationen oder Erzeugnissen bedeutet ke ine B i l l i g u n g durch d i e C I E . Obgleich große S o r g f a l t b e i der E r s t e l l u n g von Verzeich- nissen b i s zum Zei tpunkt der Drucklegung angewendet wurde, i s t es möglich, daß d iese n i c h t v o l l s t ä n d i g s ind.

Q CIE 1989

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CIE 84 8 9 9OObLY5 0003937 B T 3

The following members of TC 2-02 'Measurement of luminous f lux ' of CI€ Division 2 took part in the preparation of the technical report:

Chairman of the Committee:

Members :

Edi to r i al Commi t t e e :

Fi na1 Editing :

J . Krochmann

H. Reiter F. Rotter M. Vandermeersch O . Nielsen D. Förste J . Bastie G. Dézsi J . Schanda C. Gentile J. de Groot S. de Veer F. Hengstberger J . Moore

F. Hengstberger J. Krochmann F. Rotter S. de Veer

F. Billmeyer

Fed.Republ.of Germany

Austri a Austria Belgium Denmark Fed.Republ.of Germany France Hungary Hungary I t a ly Netherl ands Netherl ands South Africa U . K .

I I I


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CIE ô 4 ô9 I 9006345 0003938 73T m

TABLE OF CONTENTS

1 Scope

2 Termi no1 ogy

2.1 Photometric quantities 2.1.1 Luminous flux

2.1.2 Luminous intensity

2.1.3 Illuminance

2.1 .4 Luminance

2.2 Terms for measuring instruments 2.2.1 Photometer

2.2.2 Integrating

2.2.3 Integrating sphere; Ulbricht sphere

2.2.4 Box photometer

2.2.5 Photometer head

2.2.6 Acceptance area

2.2.7 Goniophotometer

3 Methods o f measurement

4 Calculation ot luminous flux from luminous intensity distribution

4.1 Measurement principle

4.2

4.3 Method of calcul ation

Measurement o f luminous intensity distribution

4.4 Sources of error

distribution

5.1 Measurement pri nci pl e

5.2 Types of goniophotometers

5 Calculation of the luminous flux from the illuminance

5.2.1 Goniphotometer with light source in a fixed posi ti on

Gociphotorneter with the light source rotated about a spatially fixed light centre

5.2.2

1 1

1 1

1 2

2

2

2

3

3

3

3

3

3

4 6

12

I V


5.2.3 Goniophotometer with the light source rotated about a vertical axis with a moving light centre

5.3 Measurement o f illuminance distribution

5.3.1 5.3.2 Angular step sizes

5.3.3 Speed o f rotation

Movement o f the photometer head

5.4 Angle encoding

5.5 Illuminance meter

5.6

5.7 Stray light

5.8 Missed luminous flux

Data acquisition and calculation o f luminous flux

5.9 Summary of error sources

5.1 O Char acteri zat i on chec kl i st 5.11 Calibrating and testing

5.11.1 Calibration

5.11.2 Testing

5.11.2.1 Luminous flux standard lamp 5.11.2.2 Luminous intensity standard lamp

5.11.2.3 Calibrated illuminance meter

5.11.3 Intercomparison

6 Measurement with an integrating sphere

6.1

6.2 Sphere theory

6.3 Spectral method

6.4 Box-photometer

6.5 Integrating sphere

Measuring pri nci pl e

6.5.1 Sphere diameter

5.5.2 Sphere paint

6.5.3 Arrangement of light source and screen

6.5.4 Influences of objects in the sphere and auxi 1 i ary 1 amp

6.6 Illuminance meter

12

13

13

14 14 15

15

15

17

17

18

18

19

19

20

20

20

21

21

21

21

23

24

24 24

25 26

28

29

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CIE 84 8 9 E 9006145 0003940 398

6.7 Data acquisition 6.8 Luminous flux standard lamps

6.9 Execution of measurements 6.10 Testing and correction

6.10.1 Correction for the influence of the sphere paint

6.10.2 Corrections for incandescent lamp measurements

6.10.3 Corrections for measuring fluorescent lamps

6.10.4 Test for stability with time

6.11 Sources o f error

6.12 Characterization o f sphere photometers

intensity or 1 umi nance 7.1 Measurement principle

7.2 Measurement and cal i brati on

7.3 Characterization

7 Determination o f luminous flux via illuminance, luminous

8 General measurement conditions

8.1 Operating conditions

8.2 Ageing

8.3 Burning position

8.4 Ambient temperature

8.5 Vibration and shock 8.6 Stabilization period

8.7 Electrical measurements

8.7.1 Measurement uncertai nty

8.7.2 Power supply and operating mode

8.7.3 Wiring

8.7.4 Execution o f the electrical measurements

8.7.5 Measuri ng ci rcui t 8.8 Ballasts

8.9 Supply voltage

9 References

Appendix

29

30

31

32 32

32

33

34

34

35

35

35

36

37

37

37

38 38

38

39

39

39

39

40

40

41 41 41 41 43

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CIE 8 4 89 W ï00bL45 000394L 224 =

MEASUREMENT OF LUMINOUS FLUX

SU MM AR Y Thi s Techni cal Report defi nes the termi no1 ogy required for 1 umi nous f 1 ux measurements. It then deals with the principles of luminous flux measurements and describes methods for the evaluation o f the illuminance distribution, the measurement o f luminous flux by means o f an integrating sphere photometer and the determination of luminous flux via luminance, luminous intensity and illuminance measurements.

The report is based on and replaces CIE Publication No. 25, 1973 'Procedures for the measurement of luminous flux of discharge lamps and for their Cali- bration as working standards' [ l ] and on the conclusions of the 'CIE- symposium on light and radiation measurement 81' [ 21. The terminology follows that in the 'International Lighting Vocabulary' [ 3 1 .

MESURES DE FLUX LUMINEUX

RESUME Ce rapport technique contient d'abord 1 a terminologie nécessaire pour les mesures de flux lumineux. Ensuite i l traite des principes de mesure du flux lumineux et donne des détails sur l'évaluation de la distribution d'éclairement lumineux, la mesure du flux lumineux au moyen d'une sphère d'integration photométrique, et la détermination du flux lumineux par l'inter- médi ai re de mesure de 1 umi nance, d ' i ntensi té 1 umi neuse et d ' écl ai rement. Ce rapport remplace la publication CIE No. 25, 1973 'Procedures for the measurement of luminous flux of discharge lamps and for their calibration as working standards' [ 1 1 dont elle est issue et sur les conclusions du 'CI E-Symposi um on Light and Radi ati on Measurement 81 ' [ 2 1 . La termi no1 ogi e est empruntée au vocabulaire international de 1 'éclairage [ 3 1 .

LICHTSTROM-MESSUNGEN

ZUSAMMENFASSUNG Dieser Techni sche Bericht enthält zunächst di e f Ür Li chtstrommessungen wichtigen Begriffsbestimmungen. Danach werden die Prinzipien der Lichtstrom- messung und Einzel heiten über die Auswertung der Lichtstärkeverteilung, die Auswertung der Beleuchtungss tärkever te i lung , die Lichtstrombestimmung iiber Leuchtdichte-, Lichtstärke- oder Beleuchtungsstärkemessungen behandelt. Die al 1 gemei nen Meßbedi ngungen werden genannt.

Dieser Bericht ersetzt und stützt sich vor allem auf die Publikation CIE No. 25, 1973 'Procedures for the Measurement o f Luminous Flux of Discharge Lamps and for their Calibration as Working Standards' [ 1 1 und auf die Ergebnisse des 'CIE-Symposium on light and radiation measurement 81' [ Z ] . Bei den Begriffsbestimmungen sind die Angaben des Internationalen Wörterbuchs der Lichttechnik [ 31 weitgehend zugrunde gelegt .

VI I


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CIE 84 89 I 9006345 0003942 160

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1 ScoDe

. . The p u r p o s e o f t h i s r e p o r t is t o review t h e main methods i n use f o r luminous f l u x measurements. One o f t h e s e methods is u s e d p r i m a r i l y by

n a t i o n a l s t a n d a r d s l a b o r a t o r i e s ( c a l c u l a t i o n from i l l u m i n a n c e or luminance

d i s t r i b u t i o n ) , one is wide ly used i n i n d u s t r y (measurement w i t h a n

i n t e g r a t i n g s p h e r e ) , w h i l e yet a n o t h e r form of measurement c a n be carr ied

o u t i n t h e l i m i t e d number o f i n d u s t r i a l l a b o r a t o r i e s w i t h access t o a

gon iopho tomete r f o r measuring luminous i n t e n s i t y d i ' s t r i b u t i o n s . While e a c h

o f t h e u s e r g roups w i l l b e p r i m a r i l y i n t e r e s t e d i n t h e method i n u s e i n its f i e l d , it is n e c e s s a r y f o r a r e f e r e n c e work on luminous f l u x measurements

t o c o v e r a l l t h e main methods u s e d for t h i s p u r p o s e and t o p u t them i n

p e r s p e c t i v e r e l a t i v e t o e a c h o t h e r .

2 Terminology <3>

2.1. P h o t o m e t r i c q u a n t i t i e s <3>

2.1.1 Luminous f l u x ( av ; a)

Q u a n t i t y d e r i v e d from r a d i a n t f l u x @e by e v a l u a t i n g t h e r a d i a t i o n a c c o r d i n g t o i t s a c t i o n upon t h e CIE s t a n d a r d p h o t o m e t r i c o b s e r v e r . For

p h o t o p i c v i s i o n

where cWe(h)/dh is t h e s p e c t r a l d i s t r i b u t i o n o f t h e r a d i a n t f l u x and V ( A )

t h e s p e c t r a l l u m i n i o u s e f f i c i e n c y .

U n i t : l m

2.1.2 Luminous i n t e n s i t y ( o f a source, i n a g i v e n d i r e c t i o n ) ( I v ; I )

Q u o t i e n t of t h e luminous f l u x ci@, l e a v i n g t h e s o u r c e and p r o p a g a t e d i n t h e e l e m e n t o f s o l i d a n g l e d61 c o n t a i n i n g t h e g i v e n d i r e c t i o n , by t h e e l emen t o f s o l i d angle.

@V I = - . d8

Unit: c d = lm-sr'l


CIE 84 89 I 9006345 0003943 O T 7

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2.1.3 I l luminance ( a t a p o i n t o f a sur face) (E ;E) V

Quot ien t of t h e luminous f l u x i n c i d e n t on an element o f t he sur face

con ta in ing the po in t , by t h e area dA of t h a t element.

- @V E v - x ( 3 )

- 2 Unit: l x = 1m.m

2.1.4 Luminance ( i n a g iven d i r e c t i o n , a t a g iven pont o f a r e a l o r imaginary surface) (Lv;L)

Q u a n t i t y def ined by the formula

V - dA cos 8 dQ L" - (4 )

where ciCD" i s the luminous f l u x t ransmi t ted by an elementary beam pass ing

through the g iven p o i n t and propagat ing i n the s o l i d angle dn con ta in ing

the g iven d i r e c t i o n ; dA is t he area o f a s e c t i o n o f t h a t beam conta in ing

the g iven po in t ; 8 i s t he angle between the normal t o t h a t s e c t i o n and t h e

d i r e c t i o n o f the beam.

- 2 - 2 -1 Unit: cd*m = 1m.m sr

2.2 Terms for measuring inst ruments

2.2.1 Photometer <3>

Instrument f o r measuring photometr ic quan t i t i es .


CIE 84 89 9006145 0003944 T33

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2.2.2 i n t e g r a t i n g photometer <3>

Photometer f o r measuring luminous f l u x , g e n e r a l l y i n c o r p o r a t i n g a n

i n t e g r a t i n g s p h e r e .

2.2.3 I n t e g r a t i n g s p h e r e ; U l b r i c h t s p h e r e <3>

Hollow s p h e r e whose i n t e r n a l surface is a d i f f u s e r e f l e c t o r , a s non-

selective a s p o s s i b l e .

2.2.4 Box photometer

A box photometer is a n i n t e g r a t i n g photometer employing a n a r b i t r a r i l y

shaped, hol low box or cavi ty i n s t e a d of a n i n t e g r a t i n g s p h e r e .

2.2.5 Photometer head (4, 17>

A photometer head c o n s i s t s o f a l i g h t - s e n s i t i v e d e t e c t o r and f a c i l i t i e s for t h e s p e c t r a l we igh t ing (e .g . c o l o u r f i l t e r s ) or f o r t h e s p e c t r a l d i s p e r s i o n

(e.9. g r a t i n g s ) o f t h e l i g h t . I t may a l s o c o n t a i n f a c i l i t i e s f o r d i r e c -

t i o n a l e v a l u a t i o n o f t h e l i g h t , e.g. d i f f u s i n g windows, l e n s e s , a p e r t u r e s .

2.2.6 Acceptance a r e a <17>

The a c c e p t a n c e area is t h e area o f t h e photometer head which is r e c e i v i n g

and d i r e c t i o n a l l y e v a l u a t i n g t h e i n c i d e n t l i g h t .

2.2.7 Goniophotometer <3>

Photometer f o r measuring t h e d i r e c t i o n a l l i g h t d i s t r i b u t i o n c h a r a c t e r i s t i c s

of s o u r c e s , l u m i n a i r e s , media and s u r f a c e s .


CIE 84 89 W 900b145 0003945 97T

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3 Methods o f measurement

The luminous f l u x o f a l i g h t source can be ca l cu la ted or measured by

d i f f e r e n t met hods:

C a l c u l a t i o n from t h e luminous i n t e n s i t y d i s t r i b u t i o n ( s e c t i o n 4) Ca lcu la t i on from t h e i l l uminance d i s t r i b u t i o n ( sec t i on 5)

Measurement w i t h a sphere photometer by photometr ic or s p e c t r a l mea-

surements ( sec t i on 6)

Measurement wi th a box photometer ( s e c t i o n 6.4)

Re la t i ve measurements v i a i l luminance, luminous i n t e n s i t y o r luminance

( s e c t i o n 7)

C a l c u l a t i o n o f t h e luminous f l u x from t h e luminous i n t e n s i t y d i s t r i b u t i o n

i s appropr ia te where measurements o f the l a t t e r a r e a l ready being made

(e.g. f o r luminai res) <5>.

The d e r i v a t i o n of t h e luminous f l u x from a measurement o f t h e i l l um inance

d i s t r i b u t i o n o f a lamp i s the method used i n many n a t i o n a l standards labo-

r a t o r i e s t o s e t up t h e b a s i c standards o f luminous f l u x . The u n i t o f lumi-

nous f l u x , the lumen, i s thus es tab l i shed i n terms o f t he SI base uni t o f

luminous i n t e n s i t y , t h e candela <6,7,12,13,14>. An accurate measurement o f

the s p a t i a l v a r i a t i o n o f t he c o l o r i m e t r i c p r o p e r t i e s o f l i g h t sources <8>

and of t h e i r s p e c t r a l power d i s t r i b u t i o n <9> can a l s o be made us ing t h i s

method.

Luminous f l u x measurements us ing a sphere photometer a re appropr ia te for:

- Measurements i n i n d u s t r i a l l a b o r a t o r i e s f o r p roduc t i on c o n t r o l

- Measurements by t e s t houses and users

- The c a l i b r a t i o n o f standard lamps (e.g. working standards) aga ins t

h ighe r o rder standard lamps, making e x t r a c o r r e c t i o n s f o r e r r o r s due t o


CIE B Y 89 W 900bLLi5 0003946 806 m

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geomet r i c , s p e c t r a l and l i g h t d i s t r i b u t i o n d i f f e r e n c e s between t h e

lamps t o be compared.

The measurement of l i g h t s o u r c e s w i t h luminous f l u x e s v a r y i n g w i t h time (e.g. a d j u s t a b l e lamps, f l a s h l a m p s )

-

- The measurement o f luminous f l u x a s a f u n c t i o n o f time.

Measurements w i t h a s p h e r e o f t h e l i g h t - o u t p u t r a t i o of a l u m i n a i r e which

is c a l c u l a t e d from t h e luminous f l u x of t h e lamp and t h e luminous f l u x of t h e l u m i n a i r e , c a n n o t be recommended i f t h e luminous i n t e n s i t y d i s t r i b u -

t i o n s of lamp and l u m i n a i r e d i f f e r c o n s i d e r a b l y .

A luminous f l u x measurement w i t h a box photometer only p r e s e n t s a d i r e c t

r e l a t i o n s h i p between t h e luminous f l u x o f t h e l i g h t s o u r c e and t h e i n d i r e c t

i l l u m i n a n c e a t a n a r b i t r a r y p o i n t a t an i n s i d e s u r f a c e of t h e box, i f t h e

r e f e r e n c e l i g h t s o u r c e and t h e l i g h t s o u r c e t o be measured have t h e same

s p a t i a l luminous i n t e n s i t y d i s t r i b u t i o n , t h e same s p e c t r a l d i s t r i b u t i o n and

same dimensions.

Measurements of s p e c t r a l r a d i a n t f l u x c a n be made w i t h a n i n t e g r a t i n g

s p h e r e photometer , f o r l i g h t s o u r c e s where t h e s p e c t r a l power d i s t r i b u t i o n

varies w i t h d i r e c t i o n (e.g. metal h a l i d e lamps) . T h i s method g i v e s a l l t h e i n f o r m a t i o n n e c e s s a r y f o r t h e c a l c u l a t i o n o f :

- S p e c t r a l power d i s t r i b u t i o n

- Luminous f l u x

- Radiant f l u x - Colour

- Colour r e n d e r i n g i n d i c e s

The d e t e r m i n a t i o n o f t h e luminous f l u x of l i g h t s o u r c e s via a measurement

of i l l u m i n a n c e , luminous i n t e n s i t y o r luminance i s o f t e n c a r r i e d o u t i n

practice t o d e t e r m i n e t h e i n f l u e n c e o f s p e c i f i c parameters (e .g . age ing ,

t e m p e r a t u r e , p o s i t i o n ) . I t u s u a l l y takes t h e form o f a r e l a t i v e measure-

ment. The method can a l s o be used f o r measuring t h e luminous f l u x of f l u o -

r e s c e n t lamps i n l i g h t i n g i n s t a l l a t i o n s < l o > .

The method u s e d f o r t h e measurement of luminous f l u x depends on t h e ava i l -

a b l e equipment . Equipment and method used are i n f l u e n c e d by:


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CIE 84 89 m 9006345 0003947 742 D

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- - Economy

- Time consunption

- Acceptable measurement unce r ta in t y .

The task o f t h e photometr ic l abo ra to ry

4 Ca lcu la t i on o f luminous f l u x f rom luminous i n t e n s i t y d i s t r i b u t i o n

4.1 Measurement o r i n c i D l e

According t o the d e f i n i t i o n , t he luminous f l u x Q can be der ived from t h e

s p a t i a l d i s t r i b u t i o n o f t h e luminous i n t e n s i t y I by t h e r e l a t i o n

where Q = 4x sr T o t a l s o l i d ang le

The luminous i n t e n s i t y d i s t r i b u t i o n can be measured w i t h a goniophotometer

a l > b

4.2 Measurement o f luminous i n t e n s i t y d i s t r i b u t i o n

The measurement o f luminous i n t e n s i t y d i s t r i b u t i o n i s descr ibed i n a sepa-

r a t e Technical Report o f t h e C I E <U>. That r e p o r t con ta ins i n f o r m a t i o n

about goniophotorneters used f o r t h e measurement o f luminous i n t e n s i t y dis-

t r i b u t i o n as w e l l as data about the execut ion o f t he measurements.

4.3 Method o f c a l c u l a t i o n

I n order t o evaluate the luminous f l u x , the luminous i n t e n s i t y should be

i n t e g r a t e d over t h e f u l l s o l i d angle as shown i n equat ion ( 5 ) . The element

o f s o l i d angle dQ can be expressed t r i g o n o m e t r i c a l l y as

d W s i n ~d E d r)

with

dO Element o f solid ang le

E > Angles depending on t h e chosen coord ina te system;

E e l e v a t i o n angle w i t h E = O a t z e n i t h and 7) azimuth angle


~~ - ~~~~

CIE 84 89 U 9006345 0003948 689

- 7 -

The angles E and r) should be s u b s t i t u t e d t o accord w i th the coord ina te

system used du r ing the measurement o f luminous i n t e n s i t y d i s t r i b u t i o n .

I n a p r a c t i c a l eva lua t ion t h e i n t e g r a l s a re rep laced by sums. I n t h a t case

t h e luminous f l u x can f o r example be c a l c u l a t e d accord ing t o t h e f o l l o w i n g

formulae:

For measurements i n

M N A-planes: @ AA 1 I(a,A) { sin(nAa) - s i n [ ( n - 1)Aal ) (7a)

m = l n=-N+l

M 4 B-planes: Q = AB 1 I ( ß , B ) { sin(nAß) - s i n [ ( n - i ) A P ] } (7b)

m = 1 n=-N+l

M N

m = l n=l C-planes: @ = AC 1 1 I(y ,C) { cos[ (n- l )Ay] - cos(nAy)}

Aar and Aß represent angular s tep s izes o f n/2N and Ay corresponds t o n/N,

w h i l e A A , AB and AC a r e g i ven by 2n/M (see appendix and reference <li>).

The smal ler t h e angular s teps t h a t a r e chosen, t h e more accurate w i l l be

the r e s u l t i n g determinat ion o f luminous f l u x . Steep luminous i n t e n s i t y

d i s t r i b u t i o n s r e q u i r e smal le r angular steps.

4.4 Sources o f e r r o r

S p e c i f i c e r r o r s i n t h e de terminat ion o f t h e luminous f l u x through an evalu-

a t i o n o f the luminous i n t e n s i t y d i s t r i b u t i o n can be caused by:

- - Too l a r g e s tep angles

- Shading o f the l i g h t source by mechanical p a r t s of the goniophotometer

Errors i n the measurement o f luminous i n t e n s i t y <Il>

and t h e ho lde r f o r t h e l i g h t source (see s e c t i o n 4.8)

- I n s t a b i l i t y o f the l i g h t source du r ing measurement

- I n s t a b i l i t y o f t h e mechanical arrangement o f t h e photometer.

5 Ca lcu la t i on o f luminous f l u x from the i l l um inance

d i s t r i b u t i o n

5.1 Measurement p r i n c i p l e

By d e f i n i t i o n , the luminous f l u x Q can be de r i ved from t he d i s t r i b u t i o n o f

i l l uminance E over a c losed sur face A around t h e l i g h t source us ing t h e re -


CIE 84 89 E 9006345 0003949 515 W

- 8 -

l a t i o n

The i l luminance d i s t r i b u t i o n can be measured by means o f a goniophotometer

over a s p h e r i c a l sur face around t h e l i g h t source. It i s n o t necessary f o r

the l i g h t source t o be exac t l y a t t he cent re o f t he imaginary sphere. I t

i s , however, recommended t h a t i t should be p o s i t i o n e d as c lose t o t h e cen-

t r e o f the sphere as poss ib le .

The m i n i m u m d is tance between the cent re o f the sphere and the photometer

head depends on t h e l a r g e s t dimension o f t h e l i g h t source t o be measured,

for pure l y mechanical reasons. It may be smal ler than the l i m i t i n g photo-

m e t r i c d is tance as l ong as t h e i l l um inance meter s t i l l eva luates i l l u m i -

nance c o r r e c t l y i n terms o f d i r e c t i o n (cos ine response), e tc . <4>.

5.2 TvDes o f aonioDhotometer

It i s poss ib le t o d i s t i n g u i s h between the d i f f e r e n t types of goniophotome-

t e r used f o r t h e measurement o f i l l um inance d i s t r i b u t i o n . I n a l l o f them

t h e l i g h t source t o be measured i s operated i n the prescr ibed burn ing pos i -

t i on .

5.2.1 Goniophotometer w i th l i g h t source i n a f i x e d p o s i t i o n

I n these goniophotometers t h e l i g h t source i s operated i n t h e prescr ibed

burn ing p o s i t i o n w i thout be ing moved. The photometer head o f t he

i l l um inance meter used f o r t h e measurement i s r o t a t e d about two axes, which

i n t e r s e c t one another a t r i g h t angles, around the l i g h t source.

I n the example depic ted i n F ig. l a t o IC these two axes can be o r i e n t e d

a r b i t r a r i l y i n space by means o f t h e ou te r frame, which remains s ta t i one ry

dur ing a measurement.

I n the terminology defined i n the Appendix, t he measurements a r e c a r r i e d

o u t i n C-planes, w i th t h e innermost frame p o s i t i o n charac ter ised by t h e

angle y and the p o s i t i o n o f the middle Frame by the angle C.


CIE 8 4 89 B! 900b145 0003950 237 = - 9 -

F i g . 1: Photograph of a model of a goniophotometer w i t h a l i g h t source, which s tays immobile i n a f i x e d p o s i t i o n

Fig. 1 a ) For t h e luminous f l u x i n t e g r a t i o n a compact l i g h t s o u r c e L (e .g . a n i n c a n d e s c e n t lamp) is s u p p o r t e d on a h o l d e r H e i t h e r from t h e t o p or t h e bot tom o f t h e frame. The h o l d e r i s f i x e d r i g i d l y t o t h e e x t e r n a l f rame, which can be t u r n e d i n t o any p o s i t i o n , b u t is k e p t s t a t i o n a r y d u r i n g t h e measurement. The two i n n e r f rames move t h e photometer E ove r t h e s u r f a c e of a s p h e r e by r o t a t i n g s i m u l t a n e o u s l y .


~ ~~~

CIE B Y 89 I 90061Y5 0003951 173

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Fig . 1 b) With t h e e x t e r n a l frame i n a h o r i z o n t a l p o s i t i o n t h e t u b u l a r lamp L is measured i n a h o r i z o n t a l p o s i t i o n . Mechanical s u p p o r t and electrical power are s u p p l i e d v i a two lamp

holders H. Two pho tomete r s E are moved o v e r t h e s u r f a c e of a

sphe re .


~

CIE 84 8 9 90Obl145 0003952 O O T

- II -

Fig. 1 c ) To c a l i b r a t e the photometer, the p a r t o f the icner frame carrying the photometer E i s turned outwards by 180 . One of the bearings o f the outer frame i s hollow. Through i t the luminous in tens i ty standard lamp N, which i s placed outside the system o f r o t a t i n g frames, i l luminates the detector E wi th a known illuminance.


~ ~~ ~

CIE 84 89 I 9006345 0003953 T 4 6

- 1 2 -

5.2.2 Goniophotometer wi th the l i g h t source r o t a t e d about a

s p a t i a l l y f i x e d l i g h t cen t re

I n these goniophotometers the l i g h t source i s pos i t i oned a t a de f ined p o i n t

i n space and r o t a t e d about a v e r t i c a l axis. The photometer head r o t a t e s i n

a v e r t i c a l plane around the l i g h t source (Fig. 2) <13,14>. The two axes

i n t e r s e c t one another a t r i g h t angles.

F ig . 2: Goniophotometer w i th the l i g h t source r o t a t e d about a v e r t i c a l a x i s and with a s p a t i a l l y f i x e d l i g h t centre.

5.2.3 Goniophotometer with the l i g h t source r o t a t e d about a v e r t i c a l

a x i s wi th a moving l i g h t cen t re

I n t h i s type o f goniophotometer t h e l i g h t source and t h e photometer head

are a t opposite ends of a r o t a t i n g beam, which i s turned around a horizon-

t a l a x i s through the middle of t h e beam (Fig. 3 ) . The l i g h t source i s

turned around a v e r t i c a l a x i s i n i t s burn ing pos i t i on . The photometric

cent re i s r o t a t e d i n a p lane around a h o r i z o n t a l axis. This type of gonio-

photometer requ i res a more invo lved mechanical cons t ruc t i on than the one

descr ibed i n sec t i on 5.2.2. However, f o r t h e same d is tance between l i g h t

source and photometer head the requ i red room he igh t is only about ha l f as

great. Both methods can a l s o be incorpora ted i n a s i n g l e design <12,14>.


~ ~- ~~ ~

CIE 84 8 9 9006145 0003954 982

- 1 3 -

Y b LIGHT SOURCE E

AXIS OF ROTATION

PHOTOM€TEME AD

Fig. 3: Goniophotometer w i t h the l i g h t source rebated abou, a v e r t A c a l a x i s and w i th a moving l i g h t centre.

5.3 Measurement o f i l l uminance d i s t r i b u t i o n

5.3.1 Movement o f t he photometer head

There are severa l p o s s i b i l i t i e s f o r measuring i l l uminance d i s t r i b u t i o n :

The i l luminance d i s t r i b u t i o n i s measured cont inously along a l i n e on

t h e sphere surface, which e n c i r c l e s t h e l i g h t source ( s p i r a l , screw-

shape). See Fig. 4 <15,16>. For t h i s type o f movement o f the photo-

meter head t h e measuring t ime f o r a g iven angular s tep s i z e i s a min i -

mum.

The i l luminance d i s t r i b u t i o n i s measured cont inuously on a c o n i c a l sur-

face (constant angle E). The photometer head i s moved i n angular s teps

o f s i z e Ac.

The i l luminance d i s t r i b u t i o n i s measured cont inuously i n a v e r t i c a l

p lane (constant angle 11). The photometer head i s moved i n angular

steps o f s i z e A v .

The i l luminance d i s t r i b u t i o n i s measured i n angular s tep s i zes Ac and

AT of the photometer head o r the l i g h t source.


~

CIE 84 89 O 9006345 0003955 819 H

- 14 -

Fig. 4 P r i n c i p l e o f c o n t i n u o u s measurement of t h e i l l u m i n a n c e d i s t r i b u t i o n on a s p h e r e surface.

5.3.2 Angular s t e p s i z e s

The d e t e r m i n a t i o n o f t h e luminous f l u x becomes t h e more a c c u r a t e t h e small-

e r t h e s t e p s izes f o r r o t a t i o n i n t h e p o l a r (Ac) a n d azimuth ( A v ) a n g l e s .

For a n accurate measurement, e s p e c i a l l y f o r l i g h t s o u r c e s w i t h a s t e e p

luminous i n t e n s i t y d i s t r i b u t i o n , a n g u l a r s t e p s izes o f Ac = A v = 0,l c o u l d

be r e q u i r e d . For l i g h t s o u r c e s w i t h a broad luminous i n t e n s i t y d i s -

t r i b u t i o n larger a n g u l a r s t e p s izes c a n b e chosen.

O

5 . 3 . 3 Speed o f r o t a t i o n

L i g h t sources, t h e luminous f l u x of which depenâs on t h e ambien t tempera-

t u r e and t h e a i r speed , may on ly be t u r n e d around t h e v e r t i c a l a x i s a t a

l i m i t e d s p e e d o f r o t a t i o n . Some l i g h t s o u r c e s c a n a l s o be i n f l u e n c e d by material moving i n s i d e t h e l i g h t s o u r c e . Where t h e r e is a p o s s i b i l i t y o f

moving p a r t i c l e s , e s p e c i a l l y d r o p s of e.g. Na, Hg, t h e a c c e l e r a t i o n s s h o u l d

be less t h a n one t e n t h o f s t a n d a r d g r a v i t y .


CIE 84 89 900bL45 0003956 755

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Note:

The permi t ted speed o f r o t a t i o n can be determined by:

- Measuring t h e luminous f l u x of t h e l i g h t source as a f u n c t i o n o f t he

speed o f r o t a t i o n

- Measuring t h e i l l uminance a t a p o s i t i o n a long t h e a x i s o f r o t a t i o n o f

the l i g h t source, which i s no t shaded by p a r t s o f the lamp holder, as a

f u n c t i o n o f t h e speed o f ro ta t i on .

The speed o f ro ta t ion , a t which t h e luminous f l u x s t a r t s changing (usua l ly

decreasing), should no t be exceeded dur ing the measurement. A uni form

movement o f t h e photometer head w i thout v i b r a t i o n i s required. For t h i s

the mechanical system has t o be w e l l balanced.

5.4 Angle encoding

I n order t o measure the i l l uminance a t a de f ined p o s i t i o n o f t h e photometer

head, two angles have t o be s e t and measured. The use of absolute angle

encoders, where the s t a r t i n g p o s i t i o n need no t be adjusted, i s recommended.

The se t p o s i t i o n i n g i s maintained even a f t e r sw i tch ing o f f t he power sup-

p l y . Other means o f angle encoding, e.g. s tepp ing motors, a r e a l s o i n

use. The i n d i c a t i o n o f the angles should be accurate t o wi th in approxi-

mately 0,1'.

5.5 I l luminance meter

The accuracy o f luminous f l u x measurements made by means o f an eva lua t i on

o f the i l luminance d i s t r i b u t i o n i s determined dec i s i ve l y by the q u a l i t y o f

t h e i l l uminance meter used. I t should be o f a very h igh q u a l i t y <17>.

5.6 Data a c q u i s i t i o n and c a l c u l a t i o n of lun inous f l u x <11,18>

I n a l l goniophotometers where luminous f l u x i s determined by eva lua t i ng t h e

i l luminance d i s t r i b u t i o n , t h i s d i s t r i b u t i o n i s measured on a spher i ca l sur-

face around the l i g h t source. I n t h a t case t h e luminous f l u x is g iven by

equation (8) as:


~~ ~~

CIE 84 89 9006145 0003957 691

- 1 6 -

TI 276 Q = E dA = r 2 I E ( E , ~ ) s i n E dE dq ( 9 )

4 Sphe re s u r f a c e

E I l l uminance on area element dA of t h e s p h e r e surface

r Sphere r a d i u s

E P o l a r a n g l e

77 Azimuth a n g l e

When t h e l i g h t s o u r c e o r the d e t e c t o r is moving con t inuous ly d u r i n g a mea-

surement t h e r e can be q u i t e l a r g e changes i n t h e i l l uminance a t t h e photo-

meter head due t o s p a t i a l or, i n t h e case of AC powered lamps, t empora l

changes i n t h e o u t p u t . An e x a c t measurement o f t h e l o c a l i l l u m i n a n c e is

t h e r e f o r e only p o s s i b l e i f t h e l i g h t s o u r c e and t h e d e t e c t o r head are s t a -

t i o n a r y d u r i n g t h e measurement. Th i s l e a d s t o long measuring times and is t h e r e f o r e n o t g e n e r a l l y p r a c t i c a b l e .

Methods f o r t h e d e t e r m i n a t i o n o f t h e " c o r r e c t " i l l uminance , which is a p p l i -

c a b l e f o r a d e f i n e d a r e a element or a d e f i n e d d i r e c t i o n ( c h a r a c t e r i z e d by

t h e a n g l e s E a n d ri), d i f f e r and canno t b e d e s c r i b e d i n a g e n e r a l i z e d way.

On t h e whole t h e measurement accu racy is i n f l u e n c e d s i g n i f i c a n t l y by t h e

a n g u l a r s t e p s izes AE and A v , t h e a n g u l a r v e l o c i t i e s de/dt and d d d t and

t h e i n t e g r a t i o n time o f t h e i l l u m i n a n c e meters ( f o r 50 Hz AC s u p p l i e s

u s u a l l y > 20 ms) .

The i l l u m i n a n c e i n t e g r a t i o n g i v e n by e q u a t i o n (9) c a n be c a r r i e d o u t by

- Direct e l e c t r o n i c i n t e g r a t i o n w i t h d i s p l a y of t h e l u m i n o u s f l u x a f t e r e v a l u a t i o n of t h e i l l u m i n a n c e d i s t r i b u t i o n . o v e r t h e whole s u r f a c e o f t h e sphe re .

A c q u i s i t i o n o f t h e measured i l l uminance v a l u e s a t a l l t h e p o s i t i o n s of

t h e photometer head, s t o r a g e of these v a l u e s and e v a l u a t i o n e.g. by

means of a desk top computer.

-

I n a d i r e c t e l e c t r o n i c i n t e g r a t i o n weight ing of t h e i l l uminance a c c o r d i n g

t o t h e s i n e o f E (see e q u a t i o n ( 9 ) ) is u s u a l l y ach ieved by u s i n g a sine-

p o t e n t i o m e t e r . I n t h e s e p o t e n t i o m e t e r s , even wi th p r e c i s i o n components,

l a r g e e r r o r s c a n occur a t small v a l u e s of E, which reduce t h e accuracy


~- ~~ ~~ ~~ ~

CIE 84 89 9006345 0003958 528

- 17 -

when measuring l i g h t sources wi th steep luminous i n t e n s i t y d i s t r i b u t i o n s .

For equal angular step s izes numerical c a l c u l a t i o n w i l l t here fore usua l l y

be more accurate than d i r e c t e l e c t r o n i c i n teg ra t i on .

I n numerical c a l c u l a t i o n i t i s a l s o poss ib le t o determine p a r t i a l luminous

f l uxes i n c e r t a i n sect ions o f s o l i d angle, e.g. the upper or lower

hemisphere, separately. - 5.7 St ray l i g h t

St ray l i g h t ( l i g h t which does n o t reach t h e photometer head d i r e c t l y from

the l i g h t source) should be avoided. This can be achieved by p l a c i n g the

goniophotometer i n a b lack room. It i s a l s o poss ib le t o p lace a h i g h l y

absorbing surface <19> behind the l i g h t source (as seen from the photometer

head), which i s moved together w i th t h e photometer head. The photometer

head should evaluate l i g h t from the s o l i d angle no t occupied by the l i g h t

source wi th as l i t t l e s e n s i t i v i t y as poss ib le and t h i s can be achieved by

p lac ing a b a f f l e tube o f t he appropr ia te dimensions, blackened on the

ins ide, i n f r o n t o f t h e photometer head. It i s poss ib le t o measure most o f

the s t r a y l i g h t by making an a d d i t i o n a l measurement o f the luminous f l u x

w i t h a b la& shade, which just covers t h e l i g h t source completely, p laced

between l i g h t source and photometer head and moving w i t h the photometer

head. The luminous f l u x measured i n t h i s way i s due only t o s t r a y l i g h t

and should there fore be subtracted from the value measured w i thout t h e

shade.

Fu r the r i n fo rma t ion about e l i m i n a t i n g s t ray l i g h t i n luminous f l u x

measurements w i t h goniophotometers can be found i n the l i t e r a t u r e <20>.

5.8 Missed luminous f l u x

A f r a c t i o n o f the l i g h t l e a v i n g the l i g h t source may be shaded by

mechanical p a r t s o f t he goniophotorneter i n a m a l l s o l i d angle, thus

causing i t t o miss the photometer head.

Any underestimation o f the luminous f l u x l eav ing the l i g h t source because

o f shading by mechanical p a r t s can be red iced by cover ing t h e shading p a r t s

with a l a y e r o f h i g h re f l ec tance mater ia l .


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- 18 -

If t h e i l l u m i n a n c e d i s t r i b u t i o n i n a small, l i m i t e d p o r t i o n o f t h e s o l i d

a n g l e canno t be measured because t h e c o n s t r u c t i o n of t h e goniophotometer

does n o t allow p o s i t i o n i n g o f t h e photometer head i n t h i s r e g i o n , t h e n t h e

luminous f l u x r a d i a t e d i n t o i t is missed. I n t h a t case t h e r e s u l t can be

c o r r e c t e d nume r ica 1 l y by e x t r a p o l a t i n g t h e i 1 l u m i na nce d i s t r ibu t i o n w i t h i n

t h i s r e g i o n of s o l i d a n g l e . Methods f o r c a l c u l a t i n g t h e e f f e c t o f t h e

s h a d i n g a r e g i v e n i n t h e l i t e r a t u r e <12>.

5.9 Summary o f e r r o r s o u r c e s

S p e c i f i c u n c e r t a i n t i e s i n t h e d e t e r m i n a t i o n of t h e luminous f l u x from t h e

i l l u m i n a n c e d i s t r i b u t i o n a r i se from:

Deformation o f mechanical p a r t s of t h e goniophotometer ( f rame, r evo lv -

i n g arm)

U n c e r t a i n t y r e g a r d i n g t h e d i s t a n c e between t h e a c c e p t a n c e area of t h e

photometer head and t h e c e n t r e o f r e v o l u t i o n

U n c e r t a i n t y w i t h r e s p e c t t o t h e p o s i t i o n o f t h e photometer head

I r r e g u l a r r o t a t i o n

Too l a r g e a n g u l a r s t e p s Measurement u n c e r t a i n t y o f t h e i l l u m i n a n c e meter

Too great a n a n g u l a r v e l o c i t y : I n f l u e n c e on t h e l i g h t o u t p u t of t h e

sou rce . P r e v e n t i o n o f t h e p r o p e r tempo-

r a l i n t e g r a t i o n of t h e luminous f l u x

Missed luminous f l u x and s h a d i n g

S t r a y l i g h t U n c e r t a i n t y r e g a r d i n g t h e p h o t o m e t r i c c a l i b r a t i o n of t h e c a l i b r a t i o n

s t a n d a r d

I n s t a b i l i t y o f t h e l i g h t s o u r c e o r o t h e r p a r t s of t h e system (e.9. amp-

l i f i e r ) d u r i n g t h e measurement.

For AC powered l i g h t sou rces :

5.10 C h a r a c t e r i z a t i o n c h e c k l i s t

I n o r d e r t o c h a r a c t e r i z e goniophotometers f o r e v a l u a t i n g t h e luminous f l u x from t h e i l l u m i n a n c e d i s t r i b u t i o n t h e f o l l o w i n g d a t a a re r e q u i r e d :

Me c h a n i c a 1 c o n s t r u c t ion:

- Type o f goniophotorneter

- Dimensions of goniophotometer


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CIE 84 8 9 9006145 0003960 186

- 1 9 -

- -

Maximum dimensions o f t h e l i g h t sources t h a t can be measured

Maximum weight o f l i g h t sources t h a t can be measured.

Geometry: - - -

Distance between cent re o f r o t a t i o n and photometer head

Angle ( s o l i d angle) not access ib le

4ngle ( s o l i d angle) ou ts ide o f which s t r a y l i g h t i s no t recorded by t h e

photometer head.

Pos i t ion ing :

- Method o f angle encoding

- Resolut ion - - Possib le angular steps

- Possib le speeds o f ' r o t a t i o n -

Method o f i n d i c a t i o n f o r s t a r t i n g p o s i t i o n

Poss ib le dev ia t ions between i n d i c a t e d and r e a l angles.

I l luminance meter and data processing: - - -

Errors o f t h e i l l uminance meter used <17,18> Method o f data a c q u i s i t i o n and processing

Data on the computer used.

5.11 C a l i b r a t i n g and t e s t i n g

5.11.1 C a l i b r a t i o n

Goniophotometers f o r t he de terminat ion o f luminous f l u x from t h e i l l u -

minance d i s t r i b u t i o n are usua l l y c a l i b r a t e d by means o f luminous i n t e n s i t y

standard lamps. The c a l i b r a t i o n app l i es t o t h e i l l uminance meter used i n

the goniophotometer, f o r which the i l l uminance i s ca l cu la ted from the l u m i -

nous i n t e n s i t y o f t he standard lamp v i a t h e photometr ic d is tance law.

5.11.2 Tes t ing

I n a d d i t i o n the goniophotometer can be t e s t e d by th ree d i f f e r e n t methods:


~~ - ~~

CIE 84 89 9006345 0003963 012

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5.11.2.1 Luminous f l u x standard lamp

A goniophotometer can be tes ted o r c a l i b r a t e d by means o f a luminous f l u x

standard lamp. I f the accuracy o f the goniophotometer i s being tested, the

measured luminous f l u x o f t h e standard should agree w i th the nominal value

o f the standard w i t h i n the s t a t e d uncer ta in ty . I f the standard i s being

used t o c a l i b r a t e the goniophotometer, t h e s t a t e d unce r ta in t y o f the stan-

dard c a l i b r a t i o n must be added t o the o ther u n c e r t a i n t i e s invo lved i n us ing

the instrument t o make measurements o f luminous f l u x .

I t i s recommended t h a t t h i s procedure be c a r r i e d ou t w i t h a t l e a s t t h ree

d i f f e r e n t luminous f l u x standard lamps.

5.11.2.2 Luminous i n t e n s i t y standard lamp

The goniophotometer can a lso be tes ted and c a l i b r a t e d by means o f a lumi-

nous i n t e n s i t y standard lamp, i f the photometer head of t he i l l uminance me-

t e r i s moved t o a pos i t i on , where the luminous i n t e n s i t y o f the standard

lamp pos i t i oned a t the cent re o f the goniophotometer i s known. For t h e

t e s t the luminous i n t e n s i t y standard and the photometer head o f the i l l u m i -

nance meter should remain s ta t i ona ry , t h e d r i v e mechanism o f t h e goniopho-

tometer being arrested. The movement o f the goniophotometer ( l i g h t source,

photometer head) may then be simulated by a s u i t a b l e computer program. The

r e s u l t i n g luminous f l u x w i l l be equal t o 4x sr t imes the luminous i n t e n s i t y

o f t he standard lamp.

5.11.2.3 Ca l i b ra ted i l l uminance meter

A t e s t o f t he goniophotometer can a l s o be performed by determining t h e re -

spons iv i t y s o f the goniophotometer's i l l uminance meter <4>, where

S = I p h /E (10)

I p h Photocurrent produced by i l l uminance meter

E I l l uminance on the acceptance area o f t h e photometer head, c a l c u l a t e d from the luminous i n t e n s i t y o f the standard lamp and i t s distance t o

t h e photometer head.

The photometer head o f the i l l uminance meter on t h e goniophotometer, f o r which the photocurrent Iph was determined dur ing the measurement o f t he

respons iv i ty , should then be disconnected and the same cur ren t should be supp l ied from a constant c u r r e n t source.


CIE 84 89 E 9006145 0003962 T59 E

- 2 1 -

A measurement sequence should then be performed.

mined i n t h i s way is given by:

The luminous f l u x deter-

r Distance between cent re o f r o t a t i o n and acceptance area o f t h e photome-

t e r head

Responsivity according t o equat ion (10) s

I p h Supplied constant photocurrent,

Th i s t e s t automat ica l ly i nc ludes t h e i n f l u e n c e of t h e movement c y c l e o f t h e

goniophotometer.

5.11.3 Intercomparison

A good method f o r f i n d i n g the unce r ta in t y o f the measurement o f luminous

f l u x obta ined w i t h a s p e c i f i c goniophotometer i s t o conpare r e s u l t s f o r t h e

same lamps measured a t d i f f e r e n t w e l l q u a l i f i e d labora tor ies . A comparison

o f t h e r e s u l t s o f measurements on t h e same lamps obta ined w i t h d i f f e r e n t

photometers (e. 9. a goniophotometer and an i n t e g r a t i n g sphere photometer)

may a l s o g ive u s e f u l i n fo rma t ion <21>.

6 Measurement w i t h an i n t e a r a t i n a sDhere


The luminous f l u x o f a l i g h t source can be measured i n a sphere photometer

by a comparison with a luminous f l u x standard lamp. I n making the measure-

ment, t h e l i g h t source and t h e s tandard lamp a r e p laced successively a t t he

same l o c a t i o n i n the i n t e g r a t i n g sphere. The i n d i r e c t i l l uminance on the

sphere sur face i s taken as a measure of t h e luminous f lux.

A sphere photometer cons is t s o f an i n t e g r a t i n g sphere, a photometer head

with read-out u n i t and - if appl icab le - means f o r data acqu is i t i on , as

w e l l as an e l e c t r i c a l supply f o r t h e measuring equipment.

6.2 %here theorv

Luminous f l u x can be measured i n a sphere photometer by means o f a


~

CIE 84 89 = 9006345 0003963 995 = - 22 -

compar ison w i t h t h e luminous f l u x of a luminous f l u x s t a n d a r d lamp. Accor-

d i n g t o U l b r i c h t ' s t h e o r y , t h e luminous f l u x o f t h e l i g h t s o u r c e is re la ted

t o t h e i n d i r e c t i l l uminance Eind on t h e i n t e r n a l s u r f a c e of t h e i n t e g r a t i n g s p h e r e by

1 - P - - A P ( 1 2 )

Eind I n d i r e c t i l l u m i n a n c e on t h e i n t e r n a l s u r f a c e of t h e s p h e r e (e.9. o n t h e accep tance area of t h e photometer head s e t f l u s h w i t h t h e s u r f a c e

o f t h e s p h e r e )

P Reflectance of i n t e r n a l s u r f a c e o f t h e s p h e r e

A S u r f a c e area of t h e s p h e r e

The f a c t o r k , where

l - P P

k = - A

is known a s t h e "sphere f a c t o r " . I n p r a c t i c e k d i f f e r s from t h e t h e o r e t i -

c a l v a l u e g i v e n by e q u a t i o n ( 1 3 ) , mainly because t h e s p h e r e is n o t empty

d u r i n g t h e measurement. For t h i s r e a s o n , k cannot be c a l c u l a t e d a c c o r d i n g

t o (131, but must be de te rmined u s i n g a r e f e r e n c e l i g h t s o u r c e ( luminous

f l u x s t a n d a r d lamp)

@N

Eind,N

Luminous f l u x o f s t a n d a r d lamp

I n d i r e c t i l l u m i n a n c e o f t h e luminous f l u x @N

Then, from e q u a t i o n s (12) t o (141, t h e luminous f l u x of t h e l i g h t s o u r c e

fol lows as


CIE 84 89 m îOOb345 0003îb4 1321 m

- 2 3 -

6.3 Spectra l method <22,23>

An impor tant parameter o f a l i g h t source i s t h e s p e c t r a l r a d i a n t f l u x Qeh, from which severa l q u a n t i t i e s can be ca lcu lated:

- Luminous f l u x

- Radiant f l u x - - - Colour render ing p r o p e r t i e s ( s p e c i a l (R i ) and general (Ra) co lour

Radiant f l u x e f f e c t i v e f o r p h o t o b i o l o g i c a l e f f e c t s

Colour ( t r i s t imulus values, co r re la ted co lour temperature)

render ing ind ices)

The s p e c t r a l r a d i a n t f l u x o f a l i g h t source can be measured w i t h an i n t e -

g r a t i n g sphere photometer, where the V ( A)-evaluating photometer head i s re -

p laced by a monochromator combined w i t h an appropr ia te detector. I n t h i s

way, the s p e c t r a l i r rad iance EeA,ind i s measured - ins tead o f t he i n d i r e c t

i l l uminance Eind - as a f u n c t i o n o f t he wavelength.

When s p e c t r a l measurements a re used i n t h i s way, t h e s p e c t r a l re f l ec tance

o f the sphere w a l l and the r e l a t i v e s p e c t r a l respons iv i t y o f the radiometer

head do no t i n f l uence t h e resu l t s . The e f f e c t o f a d i f f e r e n c e i n the

s p a t i a l f l u x d i s t r i b u t i o n s between the standard lamp and the l i g h t source

t o be measured i s the same as f o r luminous f l u x measurements w i th an

i n t e g r a t i n g sphere photometer.

A standard lamp o f known s p e c t r a l rad ian t f l u x @eA,N must be used.

The s p e c t r a l r a d i a n t f l u x @eA,x o f a l i g h t source t o be measured can be

obta ined from the r e l a t i o n

s ( h ) = Yh,N/@eh,N Spectra l respons iv i t y o f t h e sphere radiometer

Yh,x

YA,N

QeA,N

Output s i g n a l f o r l i g h t source X a t wavelength

Output s i g n a l f o r standard lamp N a t wavelength

Spectra l rad ian t f l u x o f the standard lamp N.


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CIE 84 89 9006345 0003965 768 W

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The

from the known luminous f l u x @N and known

t i o n SA,N o f the standard lamp:

luminous f l u x ax o f t he l i g h t source t o be measured can be ca l cu la ted

r e l a t i v e s p e c t r a l power d i s t r i b u -

* d h (17)

Km = 683 I m / W Maximum s p e c t r a l luminous e f f i cacy .

F o r the c a l c u l a t i o n o f o ther (non-luminous) q u a n t i t i e s the re levan t r e l a -

t i v e s p e c t r a l respons iv i t y must be used ins tead o f V ( h ) i n equat ion (17).

The var ious aspects o f an i n t e g r a t i n g sphere photometer o ther than the

s p e c t r a l ones, which are described i n sec t i on 5 , must s t i l l be taken i n t o

account.

6.4 Box-Dhotometer

A comparison o f t h e luminous f l u x o f l i g h t sources o f t he same t ype can a l -

so be performed us ing a box-photometer, i n which an a r b i t r a r i l y shaped

box o r rec tangu lar c a v i t y i s used ins tead o f an i n t e g r a t i n g sphere <24>.

6.5 I n t e g r a t i n g sphere

6.5.1 Sphere diameter

The i n t e g r a t i n g sphere must have t h e diameter l a rge enough t o take t h e b ig -

gest l i g h t source t o be measured wi th s u f f i c i e n t d is tance between the l i g h t

source and t h e sphere w a l l t o permi t adequate m u l t i p l e r e f l e c t i o n s o f t he

l i g h t w i th in the sphere w i thout undue in te r fe rence from the source i t s e l f .

I t i s recommended t h a t t he sphere diameter f o r compact lamps should be a t


- 25 -

l e a s t 10 times and Por t ubu la r lamps a t l e a s t tw ice the l a r g e s t dimension

o f t h e l i g h t source. Thus t h e sphere diameter f o r measuring f luorescent

lamps o f 1,5 m leng th should be 3 m ( f o r less c r i t i c a l measurements a

sphere diameter o f 2 m would be s u f f i c i e n t f o r t h e same purpose). The

choice o f sphere diameter i s a l so determined by the power d i s s i p a t i o n o f

t h e l i g h t source t o be measured.

The respons iv i t y o f a sphere photometer va r ies wi th the inverse square o f

the sphere diameter.

The i n t e g r a t i n g sphere should be made i n such a way t h a t no s t r a y l i g h t can

en te r t h e sphere from t h e outside.

6.5.2 Sphere p a i n t

The p a i n t f o r ' t h e i n s i d e o f t h e sphere should r e f l e c t s u f f i c i e n t l y d i f f u s e -

ly and nonselect ive ly . I t should no t show luminescence. Since the sphere

f a c t o r k (see equation (13)) i s i n f l uenced more s t rong ly by sma l l r e l a t i v e

changes i n the s p e c t r a l re f l ec tance p(A) i n the case o f a h igh re f lec tance,

i t i s recommended t h a t a p a i n t w i th a re f l ec tance o f about 0,8 <25> be

chosen. I t should, however, be po in ted ou t t h a t t he i n t e g r a t i n g p r o p e r t i e s

of t h e sphere decrease w i th decreasing ref lectance.

Sphere p a i n t s a re a v a i l a b l e commercially, f o r which the s p e c t r a l f u n c t i o n

p ( A ) / ( l - p ( A ) ) i s l i s t e d as a func t ion o f wavelength. Fig. 5 shows an

example o f a sphere p a i n t o f th is k i n d with a re f l ec tance o f 0,8 as

compared t o a pure be r ium su lphate coa t ing o f the k i n d used as a d i f f u s e

re f l ec tance standard i n t h e v i s i b l e r e g i o n (17).

The sphere should be repa in ted as o f ten as once a year, depending on the

a p p l i c a t i o n and the environment, t o keep the i n f l uence o f ageing and

p o l l u t i o n t o a minimum.


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CIE 84 87 E 7006145 0003967 530

- 26 -

a SPHERE PAINT(pr0.8) SPHERE PAINT(pr0.8) /

I I I I I I

400 450 !5ûû 550 6Oû 650 700 0 4 '

x nm --

Fig. 5 : The f u n c t i o n [ p ( h ) / (i - P ( A ) ) ] r e l o f a n improved s p h e r e p a i n t w i t h p = û,8 i n comparison t o a BaSOs-paint w i t h p E 0 ,95 .

6.5.3 Arrangement o f l i g h t s o u r c e and screen

A s c r e e n shou ld be mounted i n s i d e t h e i n t e g r a t i n g s p h e r e i n s u c h a way t h a t no d i r e c t l i g h t from t h e s o u r c e c a n r e a c h t h e photometer head.

T h e r e a re two p o s s i b l e p o s i t i o n s f o r t h e l i g h t sou rce :

a ) I t is u s u a l t o p o s i t i o n t h e l i g h t s o u r c e a t t h e c e n t r e o f t h e sphe re . I t is o r i e n t e d i n such a way t h a t t h e minimum amount o f d i r e c t l i g h t f a l l s on t h e sc reen . L i n e a r sources s u c h as f l u o r e s c e n t t u b e s s h o u l d

be p o s i t i o n e d so t h a t t h e i r a x i s c o i n c i d e s w i t h t h e l i n e photometer

head - c e n t r e of sphere. The s c r e e n is u s u a l l y p l a c e d a t a d i s t a n c e

e q u a l t o abou t 1/6 of t h e s p h e r e d i a m e t e r (1/4, i f t h e l i g h t source is small compared t o t h e s p h e r e d i a m e t e r ) away from t h e photometer head

(Fig. 6 ) . I t s h o u l d be b i g enough t o p r e v e n t d i r e c t i l l u m i n a t i o n of

t h e a c c e p t a n c e area of t h e photometer head by t h e l i g h t s o u r c e w h i l e


~~

CIE 84 8 9 9006145 0003968 477

- 27 -

a t t h e same t ime being as smal l as poss ib le <26,27>.

b) For s t rong ly d i r e c t i o n a l l i g h t sources, e.g. LEDs or r e f l e c t o r lamps,

the l i g h t source can be mounted i n the sphere w a l l w i th the l i g h t emit-

t i n g area c lose t o t h e photometer head. 4 s m a l l screen prevents d i r e c t

i l l u m i n a t i o n o f the photometer head by the l i g h t source (Fig. 7, <28>).

The screen should have the h ighest re f lec tance poss ib le and be o f a

nonselect ive and d i f f u s e nature.

L L i g h t source H A u x i l i a r y lamp wi th screen 5 Screen d Sphere diameter F Sphere p o r t f o r photometer head

Fig. 6: Arrangement f o r measuring luminous f l u x i n an i n t e g r a t i n g sphere.


CIE 84 89 U 9006145 O003969 303

- 28 -

L L i g h t source

F

S Screen

U I n t e g r a t i n g sphere

Sphere p o r t f o r photometer head

F ig. 7: I n t e g r a t i n g sphere f o r measuring t h e luminous f l u x o f l i g h t sources wi th a s t r o n g l y d i r e c t i o n a l luminous i n t e n s i t y d i s t r i b u - t ion.

The l i g h t source ho lder should have the smal lest dimensions poss ib le and as

h i g h a re f lec tance as poss ib le .

6.5.4 In f l uences o f ob jec ts i n t h e sphere and a u x i l i a r y lamp.

A l l ob jec ts i n t h e sphere, e.g. t h e screen, t h e lampholder, i n f l u e n c e t h e

r e s u l t o f the measurement. They should therefore be as smal l as possible.

The l i g h t sourae i t s e l f a l s o absorbs rad ia t i on .

The i n f l u e n c e of ob jec ts i n t h e sphere can be determined and cor rec ted f o r

by making an a d d i t i o n a l measurement w i t h an a u x i l i a r y lamp (see sec t i on

6.9).

The a u x i l i a r y lamp should be pos i t i oned opposi te t o the photometer head and

should i l l u m i n a t e the i n s i d e sur face o f the sphere d i f f u s e l y . For t h i s

purpose a smal l wh i te screen should be p laced i n f r o n t o f t h e a u x i l i a r y


~~~ ~ ~~

CIE 84 89 m 9006145 0003970 025 m

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lamp, t o prevent the d i r e c t i l l u m i n a t i o n o f t h e l i g h t source t o be measur-

ed. I f use i s made o f incandescent lamps wi th a top r e f l e c t o r i z e d bu lb

then no a d d i t i o n a l screen may be requi red.

The luminous f l u x o f t h e a u x i l i a r y lamp must n o t change w i t h time.

6.6 I l luminance meter

The measurement o f luminous f l u x i n a sphere photometer invo lves t h e mea-

surement o f t he i n d i r e c t i l l uminance on the sphere w a l l which is , p ropor t i o -

n a l t o t h e luminous f l u x o f t h e l i g h t source. For th is purpose one re-

qu i res an i l l uminance meter.

The acceptance area o f t h e photometer head should be made of a good di f fus-

i n g mater ia l , such as opa l glass, and f i t t e d t i g h t l y i n t o and f lush w i t h

the i nne r w a l l o f the sphere. I n order t o keep t h e screen (see s e c t i o n

6.5.3) small, t h e s i z e o f t h e acceptance area should a l s o be small. The

use o f a thermostated photometer head i s recommended. The openings i n t h e

sphere w a l l used f o r a t tach ing t h e photometer head should be a t about t h e

same he igh t as the l i g h t source.

A photometer head o f h i g h q u a l i t y should be used s ince the accuracy o f t h e

measurements depends on it. I t i s espec ia l l y impor tant t h a t t h e r e l a t i v e

s p e c t r a l respons iv i t y c l o s e l y approximates t o the CIE V ( h ) f u n c t i o n i n

cases where t h e lamps t o be compared have d i f f e r e n t s p e c t r a l power d i s t r i -

but ions.

I t may be convenient t o make use o f an i l l uminance meter with a b u i l t - i n

s i g n a l a t tenuator . This a l lows t h e va lue d isp layed du r ing t h e measurement

o f the luminous f l u x standard lamp t o be se t t o i t s known f l u x value, thus

f a c i l i t a t i n g a d i r e c t read-out of t h e luminous f l u x o f t h e lamp t o be mea-

sured.

For luminous f l u x measurements w i t h a sphere photometer us ing the s p e c t r a l

method, a spectroradiometer i s employed ins tead o f an i l l uminance meter.

An instrument with d i g i t a l readout i s p re fe rab le . The r u l e s for p o s i t i o n i n g the acceptance area o f t h e radiometer head a re t h e came as

those s ta ted f o r t h e photometer head o f t h e i l l uminance meter.

6.7 Data a c q u i s i t i o n

The luminous f l u x o f the l i g h t source t o be measured can be read d i r e c t l y


~ ~

CIE 84 8 9 E 9006345 0003973 TbL m

- 30 -

f rom t h e d i s p l a y u n i t , i f t h i s h a s been c a l i b r a t e d by means o f a b u i l t - i n

g a i n c o n t r o l . For r o u t i n e measurement i t is recommended t h a t a p r i n t e r be used t o r e c o r d t h e measured v a l u e of t h e luminous f l u x . For t h i s pu rpose t h e p h o t o - e l e c t r o n i c a p p a r a t u s s h o u l d have a d i g i t a l d a t a o u t p u t . For rou-

t ine measurements t h e s i m u l t a n e o u s r e c o r d i n g o f lamp vo l t age , lamp c u r r e n t

and d i s s i p a t e d power i n a d d i t i o n t o luminous f l u x is u s e f u l a s is t h e cal-

c u l a t i o n and p r i n t o u t o f t h e luminous e f f i c a c y , where a p p l i c a b l e . I f a c a l c u l a t o r is used t h e r e l e v a n t v a l u e s f o r groups of lamps (mean, s t a n d a r d

d e v i a t i o n , f a i l u r e t o r e a c h t h e minimum luminous f l u x ) can a l s o be p r i n t e d

and s t o r e d .

6 . 8 Luminous f l u x s t a n d a r d lamps

The results of luminous f l u x measurements made i n t h e s p h e r e photometer

by t h e s u b s t i t u t i o n p r i n c i p l e w i l l b e c o r r e c t i f t h e l i g h t s o u r c e t o be

measured and t h e luminous f l u x s t a n d a r d lamp used have

- - The same s p e c t r a l d i s t r i b u t i o n -

The same dimension and s h a p e

The same s p a t i a l l i g h t d i s t r i b u t i o n .

I f t h e l i g h t source t o be measured and t h e s t a n d a r d lamp d i f f e r i n one or more o f t h e s e p r o p e r t i e s , t h e n measurement e r r o r s may occur .

The i n f l u e n c e of d i f f e r e n t s p e c t r a l d i s t r i b u t i o n s c a n be e l i m i n a t e d , b u t

on ly when f u l l d e t a i l s of t h e s p e c t r a l r e sponse o f t h e measuring equipment

( i n c l u d i n g t h e photometer head and s p h e r e p a i n t ) and t h e s p e c t r a l power

d i s t r i b u t i o n s o f t h e measured l i g h t source and t h e s t a n d a r d are g iven . A

c o r r e c t i o n for t h e influence of d i f f e r e n t d imens ions and s h a p e s is p o s s i b l e

by t h e u s e o f an aux i l i a ry lamp ( s e e S e c t i o n s 6.5.4 and 6 . 9 ) .

Most luminous f l u x s t a n d a r d s t a k e t h e form o f i n c a n d e s c e n t lamps, b u t o t h e r

t y p e s o f lamp a r e a l s o used a s s t a n d a r d s .

I t is recommended t h a t a t l e a s t 3 s t a n d a r d lamps be u s e d t o c a l i b r a t e work- i n g s t a n d a r d s f o r d a i l y use . The c a l i b r a t i o n of t h e working s t a n d a r d s w i t h

t h e 3 s t a n d a r d lamps s h o u l d be r e p e a t e d a t a p p r o p r i a t e i n t e r v a l s . I n t h i s

way, a change i n one of t h e s t a n d a r d s can r e a d i l y be d e t e c t e d .


~ ~~

CIE 84 89 E ïOObl145 O003972 9T8

- 31 -

6.9 Execu t ion o f measurements

The ambient t e m p e r a t u r e is set t o t h e p r e s c r i b e d v a l u e ( u s u a l l y 25 OC).

The s t a n d a r d larrp is pu t i n t o t h e i n t e g r a t i n g s p h e r e and its measured

v a l u e is YN.

The s t a n d a r d lamp is swi t ched o f f . The a u x i l i a r y lamp is swi t ched on and

g i v e s a v a l u e Y".

The l i g h t s o u r c e t o be measured is p u t i n t h e p l a c e o f t h e s t a n d a r d lamp.

The a u x i l i a r y lamp now r e g i s t e r s a v a l u e o f YH.

After s w i t c h i n g o f f t h e a u x i l i a r y lamp t h e l i g h t s o u r c e t o b e measured

g i v e s a v a l u e o f Y.

For e a c h measurement t h e s t a b i l i z a t i o n p e r i o d of t h e l i g h t s o u r c e h a s t o be

t a k e n i n t o account .

The luminous f l u x Qj o f t h e lamp t o be measured c a n b e c a l c u l a t e d f rom t h e

luminous f l u x @N of t h e s t a n d a r d lamp and t h e measured v a l u e s u s i n g

Note:

I n e x c e p t i o n a l cases t h e s t a t e d measuring p r o c e d u r e c a n b e s i m p l i f i e d :

If t h e s t a n d a r d lamp is o f t h e same t y p e and dimension a s t h e l i g h t s o u r c e t o be measured, t h e auxi l iary lamp c a n be l e f t o u t (Y" = YH) .

If t h e s p e c t r a l d i s t r i b u t i o n s o f t h e l i g h t s o u r c e s t o b e compared are of

t h e same t y p e n e i t h e r t h e s e l e c t i v i t y o f t h e s p h e r e p a i n t no r i n a c c u r a c i e s

i n t h e s p e c t r a l f i t o f t h e photometer head t o t h e V ( h ) f u n c t i o n w i l l i n f l u -

e n c e t h e measurement accu racy .

I f t h e l i g h t d i s t r i b u t i o n o f t h e s o u r c e s t o b e compared is l a r g e l y i d e n t i -

ca l , t h e n i t is p o s s i b l e t o u s e o t h e r t y p e s o f cavi ty (e.g. boxes) i n s t e a d

o f a s p h e r e .


~~ ~ ~~

CIE B Y 89 900hL45 0003973 834

- 32 -

I f a l i g h t source w i t h a l a rge power d i s s i p a t i o n i s t o be measured, i t i s

recommended t h a t the ambient temperature outs ide the sphere be se t t o about

24 O C and the lamp s t a b i l i z e d i n t h e sphere w i t h the sphere door open.

Once the lamp has reached a s t a b l e s tate, the door should be c losed and the

measurement made when t h e i n s i d e temperature o f t h e sphere, as i n d i c a t e d by

the thermometer, has reached 25 'C.

6.10 Test ina and c o r r e c t i o n

6.10.1 Cor rec t ion f o r the in f luence of t he sphere p a i n t

The e r r o r caused by a p a i n t can be e l im ina ted by means o f a c o r r e c t i o n fac-

t o r k

Measured value o f the luminous f l u x of a l i g h t source o f i l l u m i n a n t

type z. Cor rec t i on f a c t o r f o r a l i g h t source o f i l l u m i n a n t type Z

Spec t ra l d i s t r i b u t i o n of t h e l i g h t source t o be measured

Spec t ra l d i s t r i b u t i o n o f t h e luminous f l u x standard lamp

Spect ra l re f l ec tance o f t h e sphere p a i n t

Spec t ra l luminous e f f i c i e n c y

S(h) re l Re la t i ve s p e c t r a l respons iv i t y o f t h e photometer head

6.10.2 Correct ions for incandescent lamp measurements

A c o r r e c t i o n f o r the i n f l uence o f t he s p e c t r a l re f l ec tance o f t he sphere

p a i n t can be achieved i n t h e case o f incandescent lamps by measuring t h e

luminous f l u x as w e l l as the luminous i n t e n s i t y i n a de f ined d i r e c t i o n of

t h e lamp t o be measured. An i l luminance meter w i t h a very accurate V ( A )

f i t should be used f o r the measurement, which should be c a r r i e d ou t as a

Funct ion of t h e lamp opera t ing voltage. If t h e f a c t o r k(U) where


- 33 -

@meas(U) Measured value o f the luminous f l u x a t t he vo l tage U

I ( u ) Luminous i n t e n s i t y a t the vo l tage U

i s independent o f the opera t ing vo l tage U the i n f l uence of the s p e c t r a l re -

f l ec tance o f t he sphere p a i n t can be neglected. I f , however, k(U) va r ies

w i t h the operat ing vo l tage o f the lamp, the measured luminous f l u x va lue

@meas o f t h e incandescent lamp can be co r rec ted accord ing t o

Luminous f l u x o f t h e incandescent lamp

Measured value o f the luminous f l u x a t a vo l tage U @=as K Correc t ion f a c t o r

where

U Operating vo l tage o f t h e incandescent lamp for which the luminous

f l u x measurement i s r e q u i r e d

u0 Operating vo l tage of t he incandescent lamp f o r which i t has t h e

same d i s t r i b u t i o n temperature as t h e luminous f l u x o f t h e standard

lamp.

I t i s poss ib le t o determine t h e vo l tage Uo f o r which t h e incandescent lamp

t o be measured has the same d i s t r i b u t i o n temperature as t h e incandescent

lamp used as luminous f l u x standard wi th s u f f i c i e n t accuracy by measure-

ments o f t h e r a t i o temperature T r o f b o t h lamps ( "b lue t o r e d r a t i o " ) .

Th is c o r r e c t i o n is most f requent ly requ i red when a halogen lamp i s compared

w i t h a non-halogen incandescent lamp.

6.10.3 Cor rec t ion f o r measuring f luorescent lamps

A c o r r e c t i o n f o r t he in f luence o f t h e s p e c t r a l re f l ec tance o f t he sphere


~~

CIE 84 89 = 9006345 0003975 607

- 34 -

p a i n t can a l s o be app l ied under c e r t a i n cond i t ions when measuring f l uo res -

cent lamps.

I f a f luorescent luminous f l u x standard l a w of i l l u m i n a n t type N i s used

f o r t h e measurement of t h e luminous f l u x o f f luorescent lamps, then the

value measured f o r a f luorescent lamp o f i l l u m i n a n t type Z can be cor rec ted

by means o f a c o r r e c t i o n f a c t o r determined f rom luminous i n t e n s i t y

( i l luminance) measurements ( " r e l a t i v e luminous f l u x " ) on the standard lamp

and t h e lamp t o be measured.

This method o f c o r r e c t i o n takes i n t o account t h e i n f l u e n c e o f t h e s p e c t r a l

re f l ec tance o f the sphere pa in t , bu t no t the i n f l uence o f d i f f e r e n t lamp dimensions or shapes. The method has a l i m i t e d accuracy because t h e

luminous i n t e n s i t y o f a f luorescent lamp i s not constant i n a p lane

perpendicu lar t o t h e lamp axis.

6.10.4 Test f o r s t a b i l i t y w i t h t ime

The s t a b i l i t y wi th t ime o f a sphere photometer can be i n f l uenced by

- Changes w i t h t ime i n the s p e c t r a l re f l ec tance o f t h e sphere pa in t ,

e.g. d ry ing dur ing continuous use i n the course o f a day o r changes

induced by UV- i r rad ia t ion (ye l lowing) , as w e l l as by d i r t o r dust

- Temperature dependence of the s p e c t r a l re f l ec tance p ( h ) o f the sphere

p a i n t

Fat igue o f t he photometer head

Temperature dependence o f t h e photometer head

Time dependence o f the e l e c t r i c a l supply and measuring equipment.

- - -

The s t a b i l i t y wi th t ime o f a sphere photometer can be checked by means o f

t h e a u x i l i a r y lamp w i t h a constant luminous f lux , b o t h du r ing t h e course o f

a day and over a longer per iod.

6.11 Sources o f e r r o r

The r e s u l t s o f luminous f l u x measurements made w i t h a sphere photometer can

be i n f l uenced by t h e fo l low ing :


~~ ~ ~~

CIE 84 8 9 = 9006345 0003976 5 4 3

- 35 -

D i f f e r e n t s p e c t r a l d i s t r i b u t i o n s o f t h e luminous f l u x s t a n d a r d and t h e

l i g h t s o u r c e t o be measured

D i f f e r e n t s p a t i a l luminous f l u x d i s t r i b u t i o n s o f t h e luminous f l u x

s t a n d a r d and t h e l i g h t s o u r c e t o be measured

D i f f e r e n t dimensions and a b s o r p t i o n p r o p e r t i e s of t h e luminous f l u x

s t a n d a r d and t h e l i g h t s o u r c e t o be measured

Changes i n t h e r e f l e c t a n c e o f t h e i n n e r s p h e r e wall ( a g e i n g ) . During

c o n t i n u o u s measurements t h e r e f l e c t a n c e o f t h e i n n e r s p h e r e wall may change due t o t h e i n f l u e n c e of t e m p e r a t u r e ( d r y i n g o u t ) d u r i n g t h e day.

I t is recommended t h a t a lamp be burned i n s i d e t h e sphe re , when n o t i n

u s e , i f i t is n e c e s s a r y t o keep t h e photometer warm.

The r e f l e c t a n c e may change due t o p o l l u t i o n , i n which case t h e i n f l u -

e n c e of d i r t is u s u a l l y g r e a t e r i n t h e lower hemisphere t h a n i n t h e up-

p e r one.

U n c e r t a i n t y o f t h e i l l u m i n a n c e measurement

I n s t a b i l i t y o f t h e l i g h t s o u r c e d u r i n g t h e measurement ( d i s r e g a r d i n g

t h e s t a b i l i z a t i o n p e r i o d ) .

6.12 C h a r a c t e r i z a t i o n o f s p h e r e pho tomete r s

The f o l l o w i n g d a t a are r e q u i r e d f o r c h a r a c t e r i z i n g s p h e r e photometers :

- Sphere d i a m e t e r - - - - Data on t h e i l l u m i n a n c e meter u s e d - - Data on t h e smallest measurable luminous f l u x .

P o s i t i o n i n g o f s c r e e n s and any a u x i l i a r y lamp

Data on any a u x i l i a r y lamp ( t y p e , nominal v o l t a g e s etc. ) S p e c t r a l f u n c t i o n p ( h ) / (1 -p (h ) ) o f t h e s p h e r e p a i n t

Details on d a t a a c q u i s i t i o n and d i s p l a y

7. Dete rmina t ion o f luminous f l u x v i a i l l u m i n a n c e , luminous

i n t e n s i t y o r luminance


For any g i v e n l i g h t s o u r c e p r o p o r t i o n a l i t y c a n g e n e r a l l y b e a s suned between


~~

CIE 8 4 89 I 900bL45 0003977 48T W

- 36 -

t h e luminous f l u x , t h e i l l u m i n a n c e E on a n area element i n a d e f i n e d

p o s i t i o n re la t ive t o t h e l i g h t s o u r c e , t h e luminous i n t e n s i t y I i n a d e f i n e d d i r e c t i o n and t h e luminance L o f a p a r t o f t h e luminous area o f t h e

l i g h t s o u r c e i n a d e f i n e d d i r e c t i o n as long as t h e p o s i t i o n of t h e l i g h t

s o u r c e remains c o n s t a n t .

I n t h a t case t h e luminous f l u x of t h e p a r t i c u l a r l i g h t source c a n b e d e t e r -

mined by a measurement o f E o r I o r L, p r o v i d e d t h e a p p l i c a b l e f a c t o r of

p r o p o r t i o n a l i t y (CE, CI, CL) is determined.

For some lamps a p r o p o r t i o n a l i t y between @ and E , I o r L may a l s o h o l d f o r

t h e lamp t y p e , and n o t on ly f o r t h e i n d i v i d u a l lamp (e.g. f l u o r e s c e n t

lamps).

7.2 Measurement and c a l i b r a t i o n

When measuring t h e luminous f l u x v i a an i l l uminance , luminous i n t e n s i t y o r luminance measurement, t h e measuring geometry, f o r which t h e f a c t o r s of p r o p o r t i o n a l i t y app ly , h a s t o b e f ixed . The re are a t p r e s e n t no generally a c c e p t e d s p e c i f i c a t i o n s for t h i s measuring geometry, b u t t h e y are u s u a l l y

deve loped f o r a p a r t i c u l a r a p p l i c a t i o n .

As far as t h e d e t e r m i n a t i o n o f t h e luminous f l u x of lamps u s e d i n l i g h t i n g

i n s t a l l a t i o n s is concerned, most of t h e e x p e r i e n c e o b t a i n e d s o f a r re la tes t o f l u o r e s c e n t lamps. Measurements show t h a t t h e r e is a c l o s e r e l a t i o n s h i p

between t h e luminance of f l u o r e s c e n t lamps a t a d i s t a n c e of a b o u t 20 cm from t h e ends and t h e luminous f l u x <21>.

For r e l a t i v e measurements on a s i n g l e l i g h t s o u r c e s t ray l i g h t is o f t e n o f

no importance (e.g. when measuring t h e i n f l u e n c e o f t h e ambient t e m p e r a t u r e

on t h e luminous f l u x ) . However, when measuring t h e luminous f l u x of

f l u o r e s c e n t lamps i n l i g h t i n g i n s t a l l a t i o n s v i a a luminance measurement,

s t ray l i g h t from p a r t s of t h e l u m i n a i r e o r a d j a c e n t lamps must be avoided.

T h i s is bes t done by u s i n g s u i t a b l y p o s i t i o n e d b l a c k s c r e e n s t o s h i e l d t h e

lamp and l u m i n a i r e b e i n g measured from any s u c h b r i g h t s u r r o u n d s o r

a d j a c e n t lamps.


~ ~~~~

CIE 84 8 9 S 900b145 0003978 316

- 37 -

The c a l i b r a t i o n o f measuring f a c i l i t i e s f o r t h e determinat ion o f t h e l u m i -

nous f l u x o f l i g h t sources v i a a measurement o f i l luminance, luminous in-

t e n s i t y o r luminance must be performed on a s u f f i c i e n t l y l a rge and repre-

sen ta t i ve c o l l e c t i o n o f l i g h t sources o f the des i red type, f o r which the

luminous f l u x i s known and by means o f which t h e f a c t o r of p r o p o r t i o n a l i t y

C (see equation (24)) can be detepmined. This need no t be done i n the case

o f r e l a t i v e measurements on a s i n g l e l i g h t source, e.g. f o r t h e determina-

t i o n o f t he i n f l uence o f s p e c i f i c parameters l i k e temperature, power d i s s i -

p a t i o n and pos i t ion .

7 . 3 Charac ter iza t ion

F a c i l i t i e s f o r measuring the luminous f l u x of l i g h t sources v i a a measure-

ment o f i l luminance, luminous i n t e n s i t y or luminance should be character-

i z e d by

- Lamp type, f o r which t h e f a c i l i t y i s used

- Q u a n t i t y t o be measured

- Measurement geometry and measuring arrangement

- Factor o f p r o p o r t i o n a l i t y and i t s standard d e v i a t i o n

- Data on t h e i l l uminance or luminance <17> meter used.

8. General measurement cond i t i ons

8.1 Operating cond i t i ons

A l l lamps should be operated and measured, un less otherwise agreed, under

t h e cond i t i ons s p e c i f i e d i n t h e r e l e v a n t I E C recommendations and n a t i o n a l

standards. Spec i f i ca l l y , i t must be s t a t e d whether the measurements a re t o

be made a t nominal voltage, c u r r e n t o r power. This ensures t h a t w i th in t h e

unavoidable measurement uncer ta in ty , the r e s u l t s can be compared wi th

values measured a t o ther loca t ions .

The measuring and opera t ing f a c i l i t i e s should i n f l u e n c e t h e values o f t h e

q u a n t i t i e s t o be f i x e d as l i t t l e as poss ib le . Unavoidable i n f l uences

should be taken i n t o account i n t h e eva lua t i on o f t h e measurements un-

c e r t a i n t i e s .


-

CIE 84 89 BIBI 900bL45 0003979 252

- 38 -

C a l i b r a t i o n s should be performed us ing lamps o r measuring equipment,

c a l i b r a t e d d i r e c t l y o r i n d i r e c t l y by comparison with i n t e r n a t i o n a l l y

recognized standards.

8.2 Ageing

The opera t ing parameters of lamps change over t h e i r l i f e - t i m e t o vary ing

degrees. Changes a re espec ia l l y pronounced over the f i r s t p a r t o f t h e i r

l i f e - t i m e . I n o rder t o achieve s u f f i c i e n t r e p e a t a b i l i t y o f measurements i t

is t he re fo re necessary t o age the lamps.

The du ra t i on o f ageing f o r the d i f f e r e n t types o f lamps i s s p e c i f i e d i n t h e

r e l e v a n t I E C recommendations and n a t i o n a l standards.

8.3 Burnina D o s i t i o n

The opera t ing p o s i t i o n o f a l i g h t source should conply w i th t h e re levan t

IEC recommendation and n a t i o n a l standards or with the s p e c i f i c a t i o n l a i d

down by t h e manufacturer and appropr ia te t o t h e app l ica t ion . The burn ing

p o s i t i o n must be s ta ted i n the measurement repor t .

8.4 Ambient temperature

Discharge lamps should be operated dur ing the measurement i n a draught-free

room i n such a way t h a t t h e convect ion f l o w of t h e surrounding a i r i s no t

impaired. Photometric measurement is usua l l y performed a t an ambient

temperature o f 25 OC. For l i g h t souces w i t h a s t rong ly temperature depend-

en t luminous f l u x the temperature to lerance should be F 1 C, f o r other

l i g h t sources i t should be k 3 C. I f measurements a r e made a t d i f f e r e n t

ambient temperatures th is temperature should be stated.

O

O

The temperature should be measured wi th a thermometer having a r e s o l u t i o n

o f a t l e a s t 0 , l O C . The measurement should be made a t a representa t ive

p o i n t loca ted a t about the same he igh t as the l i g h t source.

I n the case o f a goniophotometer, the d is tance between the temperature

sensor and the photometric cent re o f t h e l i g h t source t o be measured should

exceed h a l f the l a r g e s t h o r i z o n t a l dimension o f the l i g h t source by 0,5 m.


CIE 84 89 E 9006l145 0003980 T 7 4 E

- 39 -

f o r sphere photometers the temperature sensor should be p laced a t a d is -

tance from the sphere w a l l between 20 cm and 1/3 o f t he sphere diameter.

The temperature sensor must be sh ie lded from i r r a d i a t i o n by t h e source t o

be measured.

8.5 V i b r a t i o n and shock

When switched on, the lamp should no t be subjected t o acce le ra t ions exceed-

i n g 10 m/s2 (4-3000 Hz) or p o s i t i o n a l changes exceeding 30 mm (up t o

4 Hz). These cons t ra in t s w i l l be adequate f o r most lamps.

8.6 S t a b i l i z a t i o n p e r i o d

The purpose of the s t a b i l i z a t i o n p e r i o d i s t o ensure t h a t a l l impor tant

parameters have reached a steady s t a t e by t h e t ime t h e measurements com-

mence. During the s t a b i l i z a t i o n p e r i o d the same opera t ing cond i t i ons

s h o u l d apply as dur ing t h e measurement. Spec ia l a t t e n t i o n should be p a i d

t o avo id ing changes i n the burn ing p o s i t i o n and i n t h e s p e c i f i e d opera t ing

parameters (e. 9. nominal voltage, power o r cur ren t ) The s t a b i l i z a t i o n

pe r iod requ i red depends on the type of l i g h t source and the opera t ing con-

d i t i o n s . I t should be checked i n i t i a l l y by continuous moni tor ing o f t h e

readings. A l i g h t source can be considered t o be s tab i l i zed , i f these rea-

dings no longer show a t r e n d i n a p a r t i c u l a r d i rec t i on .

Note:

Some types o f l i g h t source appear t o be s t a b l e a f t e r a s h o r t i n i t i a l p e r i o d

of running and are then sub jec t t o f u r t h e r changes u n t i l a new s t a b l e situ- a t i o n is reached. These sources must be run up t o t h e f i n a l opera t ing

s t a t e be fore measurements a re made.

8.7 E l e c t r i c a l measurements

8.7.1 Measurement unce r ta in t y

D i f fe rences i n the r e s u l t s o f photometric measurements a re o f t e n due t o e r -

r o r s i n t h e measurement o r adjustment o f t he e l e c t r i c a l parameters. For incandescent lamps operat ing on AC or DC, t he unce r ta in t y o f t he e l e c t r i c a l

measuring equipment should no t exceed 0.1 X. I n t h e case o f AC operated

discharge lamps, the corresponding f i g u r e i s 0,2 %.


~~ ~~

CIE 84 89 I 900bL45 0003983 900

- 40 -

Note:

For incandescent lamps a change i n t h e vo l tage o f 1 IQ causes a change o f

about 4 Ió in the iuminous f l u x . The same change i n cur ren t causes an 8 X change i n t h e luminous f l ux .

I t should be s ta ted which o f the parameters t o be measured (voltage,

current , power) i s t o be kept constant and what o ther cond i t i ons are t o be

met.

8.7.2 Power supply and opera t ing mode

I t i s usua l l y poss ib le t o measure DC more accurate ly than AC, s ince f o r AC,

bo th the l i g h t source and the e l e c t r i c a l measuring instruments are i n f l u -

enced by a number o f var iab les, such as frequency, wave form and phase

sh i f t . Because o f the s t rong dependance o f the photometric q u a n t i t i e s on

t h e e l e c t r i c a l parameters, t h e power supp l ies used should be as s t a b l e as

possible.

The waveform o f AC power supp l ies should be c l o s e l y s inuso ida l with a

m i n i m u m o f harmonics a t o the r frequencies.

8.7.3 Wir ing

Wiring, b a l l a s t s and e l e c t r i c a l measuring inst ruments should be pos i t i oned

and, i f necessary, screened i n such a way t h a t any i n f l uence from e x t e r n a l

f i e l d s i s avoided. For t h e measurement o f lamp vo l tage o r power, t h e use

o f a s p e c i a l l y const ructed lamp holder i s recommended.

The s p e c i a l lamp holder should have four contacts, two f o r t he cu r ren t sup-

p l y (IL) and two separate ones f o r t h e vo l tage (UL)

d i r e c t l y a t t h e lamp cap. A four-e lect rode lamp ho lder reduces t h e vol-

tage measuring e r r o r t o zero, because no measurable cur ren t f lows through

t h e measuring contacts, when a h igh impedance d i g i t a l vo l tmeter i s used.

measuring o f t h e lamp


- 4 1 -

8.7.4 Execution o f t he e l e c t r i c a l measurements <29>

When measurements o f power o r o f cu r ren t and vo l tage together a re made,

on ly two arrangements a re poss ib le . E i t h e r the cu r ren t measured by the am-

meter must inc lude t h e cu r ren t through t h e vo l tmeter o r t h e vo l tage measur-

ed by the voltmeter must i nc lude the vo l tage drop across the ammeter. Be-

cause o f t h e h igh impedance o f modern e l e c t r o n i c voltmeters, t h e former ar-

rangement i s genera l ly t o be prefer red. I f the cu r ren t through the voltme-

t e r i s s i g n i f i c a n t , however, i t w i l l be necessary t o apply t h e appropr ia te

cor rec t ion . (See the recommendations i n the re levan t I E C spec i f i ca t i ons . )

The capaci ty o f the c i r c u i t may i n f l u e n c e the resu l t s , espec ia l l y i f h igher

frequencies occur as i n t h e case o f low pressure sodium vapour lamps.

Grounding e r r o r s can s u b s t a n t i a l l y i n f l u e n c e the measurements.

For accurate AC measurements on discharge lamps, inst ruments must be o f t h e

t r u e rms t ype so as t o take proper account o f t h e harmonics. When mea-

su r ing h i g h frequency discharge lamps, spec ia l methods and instruments must

be used <30>.

8.7.5 Measurement c i r c u i t

I n t h e case o f discharge lamps I E C recommendations or corresponding na t i o -

n a l standards spec i fy the c i r c u i t s f o r t he l i g h t sources t o be measured.

8 .8 B a l l a s t s

Measurements on discharge lamps must be made with reference b a l l a s t s un less

t h e lamp i s c o n t r o l l e d on c u r r e n t o r power i ns tead o f voltage. I f other

b a l l a s t s are used (e.g. f o r measurements on luminai res) , the b a l l a s t used

should be s t a t e d i n t h e measurement repor t .

8.9 Supply vo l tage

Measurements on incandescent lamps should p re fe rab ly be performed w i t h a DC

supply because o f t he h igher accuracy o f the e l e c t r i c a l measurements. Dis-

charge lamps genera l ly have t o be operated on AC.

The supply vo l tage dur ing ageing should be s t a b l e t o w i t h i n 0,5 X , dur ing

the a c t u a l measurement t o within 0 , l % and f o r c a l i b r a t i o n s wi th incandes-

cent lamps as standards t o w i th in 0,02 %.


CIE 84 89 900bl145 0003983 783

- 42 -

The t o t a l harmonic content o f t h e A C supply should no t exceed 3 5%. For t h e

operat ion o f h igh pressure lamps with a h igh p ropor t i on o f r e a c t i v e power

t h e power supply should be chosen i n such a way t h a t t h e requ i red r e a c t i v e

power can be met.

The t o t a l harmonic content i s defined as the root-mean-square (r.m.s) sum-

mat ion o f t h e i n d i v i d u a l harmonic components us ing t h e fundamental as 100

x.

Note:

This i m p l i e s t h a t the source o f supply s h a l l have a s u f f i c i e n t l y low impe-

dance compared w i t h t h e b a l l a s t impedance and care should be taken t h a t

t h i s app l i es under a l l cond i t ions o f measurement.


~

CIE 84 89 I 9006345 0003984 bLT m

- 43 -

9. References

<1>

<2> -

< 3>

<4>

<5>

<6>

<7>

<8>

<9>

<lo>

<11>

(1 2>

J.S. F r a n k l i n

O.C. Jones U. G. Berry

Schaef e r Mohan

J. Makai G. Czibula J. Schanda

D. Förs te E . Krochmann G. Sauter

J. Krochmann

D. Förs te

Procedures f o r t h e Measurement o f Luminous F lux o f Discharge Lamps and f o r t h e i r C a l i b r a t i o n as Working S t anda r ds Publ. CIE No. 25, 1973.

Proceedings Symposium on L i g h t and Radiat ion Measurement 81 Hungarian Na t iona l Committee o f CIE, Budapest, 1981.

I n t e r n a t i o n a l L i g h t i n g Vocabulary Publ. C I E No. 17.4, 1987.

Methods of Charac ter iz ing t h e Performance of Radiometers and Photometers Publ. C I E No. 53, 1982.

Au toma t ed Unive rs a l D i s t r i bu t i o n Phot orne t e r I l lum. Eng., Vol. 53, No. 3 (1958), pp. 667-678.

A New Determinat ion o f t he Lumen, Metrologia, Vol. 6, NO. 3 (1970), pp. 81-89.

A New Gonioradiometer for To ta l F lux Measurements Journal of t h e IEC, Ju ly 1974, pp. 349-353.

S p a t i a l d i s t r i b u t i o n o f c o l o r i m e t r i c c h a r a c t e r i s t i c s of metal h a l i d e 1ampsProceedings Symp. L i g h t and Rad ia t i on Meas. ' 81 pp. 47-50, Hungarian Nat. Committee o f CIE, Budapest, 1981.

Abhängigkeit des Farbor tes von der Richtung und der Brennst e l lung bes t i m m t e r L amp en typen Tagungsbericht L i c h t t . Gemeinschaftstagung 1984.

Über d i e Bestimmung des L ichts t roms von Leuch ts to f f - lampen i n Beleuchtungsanlagen L i c h t 2 (19861, pp. 136-141.

The measurement o f absolute luminous i n t e n s i t y d i s t r i b u t i o n s Publ. CIE No. 70, 1987.

E i n Goniophotometer zur genauen Bestimmung des L i c h t c t rome s Licht-Forschung 1 (19791, pp. 30-36.


~ ~ ~~

CIE 8 4 89 O 900bLLi5 0003985 556

- 44 -

<13> M.E. Thain F. Hengstberger

<14> L.A.G. Monard F. Hengstberger T. Appenroth M.E. Thain C.3. Kok R. Turner

<15> J. Krochmann P. Marx

<16> P. Marx

<17> -

<18> R . Rattunde

<19> T E Wightman F. G r u m

<20> D. Förs te G. Sauter H. M a r t i n

<21> F. Hahne

<22> O.C. Jones J.R. Moore

<23> -

A new goniophotometer f o r t h e c a l i b r a t i o n o f sma l l luminous f l u x standard lamps J. Phys. Cci. Instr. 15 (1982), p. 675-678.

Luminous f l u x measurements a t t h e NPRL by means o f a new goniophotometer Proc. 1 0 t h IMEKO Symp. Photon-Detectors, B e r l i n 1982, p. 205-214.

Ein d i g i t a l e s Meßgerät zur E rm i t t l ung des L ichts t romes aus der L i c h t s t ä r k e v e r t e i l u n g L i ch t techn ik 21 (1969) p. 97A-98A.

Das Spiralphotometer D i s s e r t a t i o n TU Ber l i n , 1973.

Methods o f cha rac te r i z ing i l l uminance meters and luminance meters: Performance, c h a r a c t e r i s t i c s and s p e c i f i c a t i o n s Publ. CIE No. 69, 1987.

Methods and e r r o r s o f measurement o f luminous f l u x with goniophotometers Proceedings Symposium on L i g h t and Rad ia t ion Measurement '81, Hung.Nat.Comm.CIE, Budapest, p. 120-132.

Low-reflectance backing ma te r ia l s f o r use i n o p t i c a l r a d i a t i o n Color Res. and Appl. 6 (1981) p. 139-142.

E l i m i n a t i o n des Fremdl ichts b e i der Lichtstrombe- s t immng m i t dem Goniophotometer Licht-Forschung 2 (1980) No. 1, p. 27-29.

Vergleichsmessungen m i t einem neuar t igen L i c h t - s t romi n teg ra to r und e i n e r U l b r i ch tschen Kuge 1 L ich t techn ik 27 (1975) p. 151-152.

The spect roradiometr ic measurement of l i g h t sources NPL Report DES 70, A p r i l 1981

Spect roradiometry P u b l i c a t i o n CIE No. 63, 1984.


CIE 84 89 m 900634.5 0003986 492 = - 45 -

<24> G. Krenzke D ie Optimierung der Meßanordnung i n runden und eckigen Hohlräumen zur Lichtctrombestimmung ausgedehnter L i c h t q u e l l e n L i ch t techn ik 21 (1969) p . 105A-106A.

<25> K. Mahr Photometrie und Farbmessung i n U-Kugeln m i t unterschied l ichem Innenaufbau und Empfängern C I E Publ. NO. 36 (1976) p. 83-91.

<26> G. Geutler über e ine Anordnung zur genauen Messung von J. Krochmann Ref lex ionsgrad und Transmissionsgrad K.-D.Reißmann Optik 54 (1980) p. 394-408, K. S t e g l i c h

<27> F. Rot te r View i n t o t h e i n t e g r a t i n g sphere through t h e observat ion window Apple Opt. 10 (1971) p. 2629-2638.

<28> -

<29> L. Morren

<30> U. Mathis

Kopfleuchten, R i c h t l i n i e n für Ausführung und Prüfung D I N 22 437 (Dez. 1962).

Mésures é l e c t r i q u e s sur les lampes à décharge (puissance-tension-courant) Revue E (Belgium) 4 (1964) No. 8 , p. 311-327.

Anwendung von e lek t ron ischen Vorschaltgeräten für Leuch ts to f f lamp en, Tagungsbericht Fachtagung Graz, 1983, LTAG.


CIE 84 89 I 9006345 0003987 329 m

- 46 -

APPENDIX

MEASURING PLANES

I n general the luminous i n t e n s i t y d i s t r i b u t i o n o f l i g h t sources (lamps or l umina i res) i s measured i n a number o f planes. The number o f luminous i n t e n s i t y d i s t r i b u t i o n curves and the s e l e c t i o n o f measuring planes depend on the k i n d o f l i g h t source and i t s use as w e l l as on the type o f goniophotometer. From the v a r i e t y of poss ib le measuring planes three systems o f planes have proven s p e c i a l l y use fu l .

A-PLANES (See Fig. 1)

The t o t a l i t y o f A-planes i s the group o f planes for which the l i n e o f i n t e r s e c t i o n goes through the photometric cent re p a r a l l e l t o the e m i t t i n g area and perpendicular t o the assumed a x i s o f t h e l i g h t source.

Note:

The system o f A-planes i s coupled r i g i d l y t o the l i g h t source and f o l - lows i t s t i lt if the l i g h t source i s t i l t e d .

4

\ LINE OF INTERSECTION k4

Fig. 1: A-planes


~

CIE 84 8 9 W 900b l45 0003988 265 = - 47 -

B-PLANES (See Fig. 2)

The t o t a l i t y o f B-planes is t h e group o f p l a n e s f o r which t h e l i n e o f i n t e r s e c t i o n goes through t h e p h o t o m e t r i c c e n t r e and is p a r a l l e l t o t h e assumed a x i s o f t h e l i g h t s o u r c e and is p e r p e n d i c u l a r t o t h e l i n e o f i n t e r - s e c t i o n of t h e A-planes. Note:

The s y s t e m o f B-planes is coup led r i g i d l y t o t h e l i g h t s o u r c e and f o l - lows its tilt i f t h e l i g h t s o u r c e is t i l t e d .

OF INTERSECTION AND OF LIGHT SOURCE

Fig. 2: B-planes

C-PLANES (See Fig. 3)

The t o t a l i t y o f C-planes is t h e group of p l a n e s f o r which t h e l i n e o f i n t e r s e c t i o n is t h e vertical l i n e th rough t h e p h o t o m e t r i c c e n t r e .

Note:

The system of C-planes is g e n e r a l l y o r i e n t e d r i g i d l y i n s p a c e and does no t f o l l o w a tilt i n t h e l i g h t s o u r c e . The l i n e of i n t e r s e c t i o n of C- p l a n e s is on ly p e r p e n d i c u l a r t o t h e l ines o f i n t e r s e c t i o n of t h e A- and B-planes f o r z e r o t ilt (6 = O ) o f t h e l i g h t s o u r c e .

I n some cases t h e t o t a l i t y of C-planes is a l s o r e f e r r e d t o a s t h e group o f p l a n e s whose l i n e of i n t e r s e c t i o n is t h e l i n e of i n t e r s e c t i o n o f AO- and Bo-planes ( s e e Fig. 4). I n t h a t case t h e s y s t e m of C-planes is a l s o r i g i d - l y coupled t o t h e l i g h t s o u r c e ( a s is t h e case f o r t h e A- and B-planes) .


- 48 -

‘270

(PERPE.NMCUCAR To MEASURING PLANES)

Fig. 3: C-planes (6 tilt a n g l e o f l u m i n a i r e )

LINE OF INTERSECTION (OF Ao- AND Bo- PLANE)

AXIS ûf LIGHT S O ü K E

Fig . 4: C-planes wi th r i g i d c o u p l i n g t o t h e l i g h t source


~~~ ~~ - -~ ~

CIE 84 89 = 9006345 0003990 933 - 49 -

C O N I C A L S U R F A C E S (F ig . 5)

F o r some goniophotometers i t i s convenient t o measure the luminous in- t e n s i t y d i s t r i b u t i o n curves a t constant po la r angles and t o describe the results as curves on con ica l surfaces. The a x i s o f the cone corresponds t o the l i n e o f i n t e r s e c t i o n o f the C-planes.

* LIGHT SOURCE

LUMINOUS INTENSITY DISTRI BUTION

Fig. 5 : Conica l surfaces

SYMBOLS FOR PLANE ANGLES

The ti lt angles o f planes are designated by an index. The tilt angles o f t h e A- and B-planes are taken from -180O through O o t o 180°, those o f the C-planes from O o t o 360 o (semiplanes). The opening angle o f t h e c o n i c a l surfaces i s measured r e l a t i v e t o the l i n e o f i n t e r s e c t i o n o f the C-planes.

The fo l l ow ing symbols are used ( f o r angle symbols see Figs. 1-51:

- the angles i n the A-plane have the symbol CI and are measured from t h e l i n e perpendicu lar t o the l i n e o f i n t e r s e c t i o n o f t he A- planes

- t h e angles i n the B-planes have the symbol ß and are measured from the l i n e perpendicular t o the l i n e of i n t e r s e c t i o n o f the B-planes

- the angles i n the C-plane have the symbol y and are measured from t h e l i n e o f i n t e r s e c t i o n of the C-planes i n the downward d i r e c t i o n


~~~

CIE 84 8 9 = 900bL45 0003993 85T =

I C-pianes

Con ica l surfaces

- 50 -

Y C

C Y

- t h e angles on the c o n i c a l sur faces have t h e symbol C and are measured from the Co-plane.

-

The t i l t angles o f the planes are added as i nd i ces t o the re levant planes.

T i l t angle of p lane

RELATIONSHIPS

Angle i n t h e p lane

A c e r t a i n d i r e c t i o n i n each system o f planes i s character ized by two angles:

t a n B = t a n a/cos A t a n C = t a n a /s in A t a n A = t a n @/cos B t a n C = s i n B/ tg ß

t a n A = cos C.tg y

t a n i3 = s i n C.tg y

- -

an angle i n one p lane o r c o n i c a l sur face and angle fo r t he t i l t o f t h e plane o r con ica l surface.

s i n ß = s i n A COS a

cos y = cos A . cos a

s i n CI s i n 8 cos 8 cos y = cos B . cos ß

s i n a = s i n C . s i n y s i n ß = cos C . s i n y

Table 1 shows the angle symbols commonly used i n the var ious systems o f planes.

TABLE 1

Angle symbols

The conversion equations l i s t e d i n Table 2 ho ld f o r t he angles i n Table 1.

TABLE 2

Conversion equations f o r s y s t e M o f planes

D i r e c t i o n


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