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C I E
7 0
87
9006345 0003038 703
COMMISSION
INTERNATIONALE DE
L ECLAIRAGE
INTERNATIONAL
COMMISSION
ON
ILLUMINATION
INTERNATIONALE BELEUCHTUNGSKOMMISSION
THE
MEASUREMENT
OF
ABSOLUTE
LUMINOUS INTENSITY DISTRIBUTIONS
PUBLICATION CIE Ni) 70 (1987)
A- I033 VIENNA. P . O BOX 159 AUSTR IA
CENTRAL
BUREAU
OF
THE
CIE
pyright International Commission on Illuminationovided by IHS under license with CIE
Not for Resalereproduction or networking permitted without license from IHS
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C I E 70 8 7 006145 0003019 6 4 T
Thi s Techni cal Repor t has been pr epar ed
by CI E
Techni cal Comm t t ee 2. 2
Detectoorc ( now wi t hi n CI E Di vi s i on 2) and has been appr oved by t he Counc i l o f
t he Comm ss i on I nt e rnat i ona l e de 1 Ec l a i r age f o r s t udy and appl i cat i on. The
document r epor t s on cur r ent knowl edge and exper i ence wi t hi n t he spec i f i c f i e l d
o f
l i ght and l i ght i ng des c r i bed, and i s i nt ended t o be used by t he CI E
members h i p and ot her i nter est ed par t i es . i t shoul d be not ed, however , t hat t he
s t a t u s
of
t hi s document i s advi sor y and not mandat or y. The l at est
CI E
pr oceedi ngs or J our nal shoul d
be
consul t ed r egard i ng poss i bl e subsequent
amendment s .
Ce r appor t t echni que a ét é pr épar é par l e Com t é Techni que CI E 2. 2, Détecteurs
( mai nt enant par t i e d e l a Di v i s i on 2 de l a C IE ) , et a ét é appr ouvé, par l e
Consei 1 de
1
a Comm ss i on I nt ernat i ona l e de 1 Ecl ai r age, pour ét ude et
appl i cat i on. Le document t r a i t e des connai ssances cour ant es et de l expér i ence
dans l e domai ne s péc i f i que i ndi qué de l a l um ér e et d e l éc l ai r age, et i l e s t
ét abl i
pour l usage des membr es de l a
CI E
et aut r es gr oupement s i nt éressés . I l
f aut cependant no te r q ue ce document es t i ndi cat i f et non obl i ga to i r e. Pour
c onnai t r e d évent uel
s
amendement s, consul t er l es p l us r écent s compt esr endus ou
l e J our nal de l a CI E.
Di eser Techni sche Ber i cht i s t vom CI E- Techni schen Kom t ee 2. 2 Detektoren
z. Z.
i n der CI E Di v i s i on 2) ausgear be i t e t und vom Rat de r Comm ss i on I nt e rnat i ona l e
de 1 Ecl a i r age gebi l l i gt worden. Das Dokument ber i cht et über den derz e i t i gen
St and von W ssen und Er f ahr ung i n dem behandel t en Gebi et von L i cht und
Bel euchtung;
es
i s t zur Verwendung dur ch CI E- Mi t g l i eder und dur ch ander e
I nter ess i er t e best i mmt . Es so l l t e j edoch beachtet werden, da6 das Dokument
e i ne Empf ehl ung und ke i ne Vorschr i f t i s t . Di e neue- s t en CI E- Tagungsber i chte
oder das neues t e CI E- J our nal s ol l t en i m Hi nbl i c k auf mögl i c he s pät er e
Änder ungen z u Rat e gezogen wer den.
Any ment i on
o f
organi sat i ons or pr oducts does not i mpl y endors ement by
t he CI E. Whi l s t ever y ca re has been t aken i n t he compi l a t i on o f any
l i s t s , up t o t he t i me of go i ng t o pr ess , t hese may not be compr ehens i ve.
Tout e ment i on d or gani sme ou de pr odui t n i mpl i que pas une pr éf ér ence de
l a CI E. Mal gr é l e s oi n appor t é
4
l a compi l at i on
de
t ous ? es document s
j usqu à
l a
m s e sous pr es s e, c e t r avai l n e s aur ai t êt r e exhaus t i f .
Di e Er wähnung von Or gani sat i onen oder Er zeugni ss en bedeut et kei ne
Bi l l i gung dur ch di e CI E. Obgl ei ch gr oße So rg f a l t bei de r Er s t e l l ung von
Verze i chni s sen b i s zum Zei t punkt der Dr uck1 egung angewendet wur de, i s t
es mögl i c h, d aß di e s e ni c ht v ol l s t ändi g s i nd.
O CI E 1987
I I
pyright International Commission on Illumination
ovided by IHS under license with CIE
Not for Resalereproduction or networking permitted without license from IHS
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C I E
70 8 7 9006145 0003020
3 b L
The
f o l l o w i n g members
o f Committee T C - 2 . 2
t oo k p a r t i n t h e p r e p a r t i o n o f
t h e t e c h n i c a l r e p o r t :
Les membres s u i v a n t du c o m i t é TC-2.2 o n t p a r t i c i p é s a l a p r e p a r a t i o n
d u
r a p p o r t t e c h n i q u e :
Die
f o lg e n de n M i t a r b e i t e r d e s K o m it ee s
T C - 2 . 2
h a b e n
s i c h
a n
der
A u s a r b e i t u n g d e s T e ch n i sc h en B e r i c h t e s b e t e i l i g t :
Chairman:
H e n g s t b e r g e r , F*
Cogno, J A
Farmer, A
J D
Reiter, H*
Pact ie l s ,
R
A n d r e y t c h i n e ,
R
Budde, W
Krt il J
Nielsen, O*
J a n e s t ,
A
Timonen , T
Riemann , M
G e u t l e r , G
Betts,
D
B
S c h a n d a , J*
Artom,
M
N a n j o ,
M
Balder, J
J
H i s d a l ,
B
L i p o w s k i , M
Musa, G
C o r r o n s ,
A*
O t t o s o n , A
Blaser, P*
Z a l e w c k i , E F
I g n a t i e v , V G
S o u t h Africa
A r g e n t i n a
A u s t r a l i a
A u s t r i a
B e l g i u m
B u l g a r i a
C a n a d a
C z e c h o s l o v a k i a
Denmark
F r a n c e
F i n l a n d
Germany, D e m . Rep.
Germany, Fed. Rep.
Great B r i t a i n
Hungary
I t a l y
J a p a n
N e t h e r l a n d s
Norway
P o l a n d
Romania
S p a i n
Sweden
S w i t z e r l a n d
U S A
U S S R
S u b c o m m i t t e e
on
" Me as ure me nt o f l u m in o us i n t e n s i t y d i s t r i b u t i o n s " :
Chairman:
Krochmann , J
Rotter ,
F
V a n d e r m e e r s c h ,
M
G
Bas t i e ,
J
Germany, Fed. Rep.
A u s t r i a
B e lg iu m
F r a n c e
I I I
pyright International Commission on Illuminationovided by IHS under license with CIE
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____
C I E 70
87
9006345 0003021 2 T B
Moore,
3 R
Rattunde,
R
Förste,
D
D e z s i ,
G
G e n t i l e ,
C
d e
Groot,
J
J
De
Veer,
S
M
and members o f
TC-2.2
m ark ed *
E o i t o r i a l C o m m i t t e e :
Chairman:
Krochmann , J
V a n d e r m e e r s c h M G
Moore,
J
R
V erm eu len ,
J
H e n g s t b e r g e r , F
F i n a l e d i t i n g :
B i l l m e y e r , F
Great B r i t a i n
Germany, F e d .
Rep.
Germany, Fed . Rep .
Hungary
I t a l y
N e t h e r l a n d s
Nether
a n d s
Germany, Fed. Rep.
B e l g i u m
Great Britain
N e t h e r l a n d s
South Africa
USA
I V
pyright International Commission on Illumination
ovided by IHS under license with CIE
Not for Resalereproduction or networking permitted without license from IHS
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CONTENTS
Page
1 T E R M I N O L O G Y
......................................................
1
1.1 Q u a n t i t i e s
...................................................
1
1.1.1 L u m i n o u s i n t e n s i t y .....................................
1
1 . 1 . 2 I l l u m i n a n c e
............................................
1
1.1.3 L u m in an ce ..............................................
1 .2 L um inous i n t e n s i t y d i s t r i b u t i o n body ......................... 2
1 . 3 Luminous i n t e n s i t y d i s t r i b u t i o n c u r v e
........................
2
1 . 4 I s o c a n d e l a d ia g ra m ........................................... 2
1.5 M e a s u r i n g f i e l d and m e a s u r i n g - f i e l d a n g l e i n
l u m i n a n c e mea-
s u r e m e n t s .................................................... 2
1 .6 T erm s for m e a s u r i n g i n s t r u m e n t s
..............................
3
1 . 6 . 1 P h o t o m e t e r
.............................................
3
1 . 6 . 2 G o n i o p h o t o m e t e r
........................................
3
1 . 6 . 3 P h o t o m e t e r h e a d
........................................
3
1 . 6. 4 A c c e p t a n c e a r e a ........................................ 3
1 . 7 P h o t o m et r i c c e n t r e o f a l am p or l u m i n a i r e ) ..................
4
1.8 S t r a y l i g h t ..................................................
4
1 . 9 L i m i t i n g p h o t o m e t r ic d i s t a n c e
...............................
4
2
.
PRINCIPLES OF LUMINOUS INTENSITY MEASUREMENTS
....................
4
2 .1 P h o t om e t r i c d i s t a n c e law .....................................
4
2 .2
L u m i n a n c e i n t e g r a t i o n ........................................ 6
3 . TYPES OF PHOTOMETER HEADS ........................................ 6
3 . 1 P h o t o m e t e r h e a d f o r measuring i l l u m i n a n c e
.....................
6
3 . 2
P h o t o m e t e r head f o r l um i na n ce i n t e g r a t i o n .................... 7
3 .2 .1 C o n s t r u c t i o n ...........................................
7
3 . 2 . 1 . 1 P h o t o m e t e r h e a d w i t h l e n s
......................
7
V
pyright International Commission on Illumination
ovided by IHS under license with CIE
Not for Resalereproduction or networking permitted without license from IHS
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3.2.1.2 Photometer head w i t h p a r a l l e l o r i e n t e d o p t i c s
.. 8
3.2.1.3 Photometer head
w i t h
tubes
..................... 8
3.2.2 Influence
o f
inhomogeneous i l lumination .............. 11
3.2.3
In f lu ence o f the measur ing- f ie ld ang le ............... 12
4
.
MEASURINC
PLANES
.................................................
13
4.1 A-Planes .................................................... 13
4.2 B-Planes
.................................................... 14
4.3 C-Planes .................................................... 14
4.4 Conica l surfaces ............................................ 16
4.5
Symbols f o r
plane angles
....................................
16
4.6 Relat ionships
...............................................
17
G O N I O P H O T O M E T E R W I T H FACILITY FOR TURNING THE LIGHT SOURCE ....... 18
5 . 1 P r i n c i p l e ................................................... 18
5.2 Appl icat ion
.................................................
18
5
.
5.3
Co ns t ru c ti o n p r i n c i p l e s
.....................................
18
5.4 Au x i l i a r y d e t e c t o r s ......................................... 19
6 . GONIOPHOTOMETER WITH M O V I N G PHOTOMETER HEAD ...................... 21
6 . 1 P r i n c i p l e
...................................................
21
6.2 App l ica t ion .................................................
21
6.3 Const ruct ion Pr inc ip l es
..................................... 21
7
. GONIOPHOTOMETER WITH
R O T A T I N G M I R R O R ............................. 24
7 . 1 P r i n c i p l e
...................................................
24
7 . 2 App l i ca t ion ................................................. 25
7.3 Cons truc tion p r i nc i p l es
.....................................
25
ANGLE MEASUREMENT
................................................
26
.
8 . 1
P o s s i b i l i t i e s
............................................... 26
8.2 Requirements
................................................
27
9
. PHOTOELECTRONICS AND D A T A PROCESSING .............................
27
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C I E
7 0 8 7 M 7006345 0003024
T O 7
M
10. GENERAL MEASURING
C ON D IT ION S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
1 0 . 1 Operat ing condit ions
.......................................
28
10.2 Ageing ..................................................... 29
10.3 Burn ing pos i t ion
...........................................
29
10.4 Ambient temper atu re
........................................
29
10.5 Vibrat ion and shock ........................................ 30
10.6 S t a b i l i z a t i o n p e r i o d ....................................... 30
10.7
Electr ical measurements .................................... 30
10.7.1 Measurement un c er ta i nt y ............................. 30
10.7.2
Power type and operating
mode
.......................
31
10.7.3
Wir ing .............................................. 31
10.7.4 Execution
o f
the e l e c t r i c a l measurements ............
31
10.7.5 Measu r ing c i r cu i t ................................... 31
10.8
Ba l l a s t s
................................................... 32
10.9
S u p p l y vo l tage ............................................. 32
10.10
Execut ion
o f
t h e
measurements
..............................
32
11. C O R R E C T I O N
OF
MEASUREMENT RESULTS ................................ 33
1 2.
PRESENTATION
OF
RESULTS
.......................................... 33
1 3. MECHANICAL ADJUSTMENT
............................................ 34
13.1 Goniophotorneter
w i t h
f a c i l i t y f o r t r a i n i n g
t h e
l i g h t s our ce
.
34
13.2 Goniophotorneter
with
moving photometer head
................. 35
1 3 . 3
Goniophotometer
wi th
r o t a t i n g mirror
........................
35
1 4. CALIBRATION ...................................................... 35
1 4 . 1
Luminous in tensi ty standard ................................. 36
14.2 Calibrated i l luminance meter ................................
36
14.3
Relative measurements
....................................... 36
1 5
. E R R O R
SOURCES
AND MEASUREMENT A C C U R A C Y ........................... 36
1 5 . 1
Mechanical arrangement
......................................
36
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CIE
70
87 006345 0003025 9 4 3
1 5 . 2 A n g l e
measurements
a nd a n g u l a r s t e p size
....................
37
15.3 I n f l u e n c e
o f
r o t a t i n g
mirror o r
p h o t o m e t e r head f o r l u m i n a n c e
i n t e g r a t i o n .................................................
37
15.4
S t r a y l i g h t ................................................. 38
1 5. 5 R e l a t i v e s p e c t r a l r e s p o n s i v i t y
..............................
39
15 .6 I l l u m i n a n c e and l u m i n a n c e
meter
............................. 39
1 5 . 7 Da ta p r o c e s s i n g ............................................. 39
15 8 L i m i t i n g photometric d i s t a n c e ............................... 39
1 5 . 9 O p e r a t i n g c o n d i t i o n s ........................................ 39
15.10
Photometric s t a n d a r d ....................................... 40
16
.
C H A R A C T E R I Z A T I O N
OF
GONIOPHOTOMETERS
.............................
40
1 6 . 1 M e c h a n i c a l a r r a n g e m e n t s ..................................... 40
16.2
A n g l e e n c o d i n g
.............................................. 41
1 6 . 3
P h o t o m e t e r h e a d ............................................. 41
16.4 P h o t o e l e c t r o n i c s an d d a t a p r o c e s s i n g ........................
41
17
. LITERATURE ....................................................... 42
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C I E
70 87 9006345 0003026
B A T
SU IMARY
T h i s t e c h n i c a l report c o n t a i n s t h e t e r m i n o l o g y r e q u i r e d
f o r
m e a s u r e m e n t s o f
l um in o u s i n t e n s i t y d i s t r i b u t i o n s .
I t
a l s o s u m m a r i z e s t h e p r i n c i p l e s o f l u -
m i nous
i n t e n s i t y m e a s u r e m e n t s a n d
t h e requirements
f o r t h e p h o to m e te r h e a d s
e m p l o y e d
fo r such
m e a s u r e m e n t s . The c o o r d i n a t e systems u s e d f o r t h e mea-
s u r em e n t a nd r e p r e s e n t a t i o n o f l u m in ou s i n t e n s i t y d i s t r i b u t i o n s are d e s -
c r i b e d . The t y p e s o f g o n i o p h o t o m et e rs , p o s s i b i l i t i e s f o r a n g l e e n c o d i n g ,
c h a r a c t e r i s t i c s
o f t h e
p h o t o - e l e c t r o n i c system a n d t h e a c q u i s i t i o n a n d p ro -
c e s s i n g o f t h e d a t a i n m e as ur e m e nt s o f l um i n ou s i n t e n s i t y d i s t r i b u t i o n s are
d i s c u s s e d i n d e t a i l . O t h e r s u b j e c t s c o v e r e d a r e t h e pow er s u p p l y , t h e mea-
s u r i n g c o n d i t i o n s a nd t h e e x e c u t i o n , c o r r e c t i o n a nd r e p r e s e n t a t i o n o f l u m i -
n o u s i n t e n s i t y d i s t r i b u t i o n m ea su r e me nt s .
The
v a r io u s s e c t i o n s c o n t a i n
s u f f i c i e n t d a t a on t h e r e q u i r e d c h a r a c t e r i z a t i o n
o f
g o n i o p h o t o m e t e r s .
T h e r e p o r t is b a s e d m a in l y o n t h e T e c h n i c a l R e p o r t
o f
C I E T e c h n i c a l C o m m i t -
tee
TC-2.2 o n " M e th od s o f c h a r a c t e r i z i n g t h e p e r f o r m a n c e o f r a d i o m e t e r s a n d
p h o t o m e t e r s
[l]
as w e l l a s on C I E p u b l i c a t i o n s 24 [ 2 ] , 2 7 [ 3 ] a n d 43 [ 4 ] .
The
t e r m i n o l o g y is l a r g e l y b a s ed on t h e I n t e r n a t i o n a l L i g h t in g V o ca b u l a ry
PI
L A MESURE DES DISTRIBUTIONS
D'INTENSITE
LUMINEUSE ABSOLUE
Ce r a p p o r t t e c h n i q u e c o n t i e n t
l a
t e r m i n o l o g i e n é c e s s a i r e p o u r
l a
m e s u r e d e s
d i s t r i b u t i o n s d ' i n t e n s i t é l u m i n eu se . 11 r é s u m e a u s s i
l es
p r i n c i p e s d e me-
s u r e de l ' i n t e n s i t é l u m i ne u s e
e t
les q u a l i t é s r e q u i s e s p o u r l a
tete
p h o t o -
m é t r i q u e u t i l i s é e p o u r d e
te l les
mesures. Les systémes d e c o o r d o n n é e s
ut i l i sés p o u r l a m e s u r e
e t l a
r e p r g s e n t a t i o n d e s d i s t r i b u t i o n s d ' i n t e n s i t é
l u m i n eu s e s o n t d é c r i t s . Les types de g o n i o p h o t o m è t r e ,
l e s
p o s s i b i l i t é s d e
r e p é r a g e a n g u l a i r e , l e s c a r a c t é r i s t i q u e s
ch
system é l e c t r o n i q u e e t
ce l l es
d e l ' a c q u i s i t i o n
e t du
t r a i t e m e n t d e s d o n n é e s d a n s les m e a su re s d e d i s t r i
b u t i o n d e l ' i n t e n s i t é l um i n eu se s o n t d é c r i t e s e n d é t a i l .
Les
a u t r e s s u j e t s
t r a i t é s
s o n t l ' a l i m e n t a t i o n é l e c t r i q u e ,
les
c o n d i t i o n s
de
m e s u r e s e t l e u r
e x é c u t i o n , l a c o r r e c t i o n e t l a r e p r é s e n t a t i o n des m es ur e s d e d i s t r i b u t i o n
d' i n t e n s i t é l um i ne u se . Les d i f f é r e n t e s s e c t i o n s c o n t i e n e n t d e s do nn ée s
s u f f i s a n t e s sur les c a r a c t é r i s t i q u e s r e q u i s e s p o u r
les
g o n i o p h o t o m è t r e s .
Ce r a p p o r t s 'a p p u y e p r i n c i p a l e m e n t s u r l e r a p p o r t t e c h n i q u e du c o m i t é tech-
n i q u e
2.2
de l a C I E "M eth od s o f c h a r a c t e r i z i n g t h e p e r f o r m a n c e o f r a d i o -
meters
a n d p h o t o m e t e r s " [i] a i n s i q u e s u r
les
p u b l i c a t i o n s
C I E
no
24 [Z],
27 [ 3 1 , e t 43 [4].
L a t e r m i n o l o g i e est l a r g e m e n t e m p r u n t é e au V o c a b u l a i r e
I n t e r n a t i o n a l
de
1
E c l a i r a g e
[
51 .
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9006245 0003027 716
ZUCANENFASSUNG
D I E MESSUNG
D E R
A B S O LUT
EN
L
I H sT
ÄRK E
VE
R T E
IL
UNG
D i e s e r Technische Bericht enthal t zunächst die für Lichtstarkemessungen
wi ch tig en ßegriffsbectimmungen. Danach werden di e Pr in zi pi en der
Lich t -
stärkemessung
u n d
4ngaben Über
d i e
dementsprechend zu verwendenden
P h o t o -
meterköpfe zusammengestellt.
D i e
fü r die Messung und Darstellung
d e r
L i ch ts tä rkev e r te i l i J ng verwendeten Ebenensysteme werden angegeben. ßeson-
ders werden die Arten
von
Goniophotometern,
d i e
Mögl ichkei ten der
Winkelerfassung, Aussagen Über di e Ph oto ele kt ron ik und di e Re gi st ri er un g
und Datenverarbeitung be i der Messung der Li ch ts tä rk ev er te i l ung behandelt .
Auch Aussagen
zur
Spannungcversorgung, ZU den tkß edingungsn und zur
Durchführung, Korr ektu r und Dar ste l l ung
der
L i c h t s grkemessungen werden
gemacht. Re i den ei nz elnen Ka p i t e l n werden ausreichende Angaben Über d i e
notwendige Kennzeichnung von Goniophotometern aufgeführt.
D iese r ße r ich t s tü t z t s i ch vo r a l lem a u f den Technischen Bericht des C I E
Technischen
Komi
tees
TC-2.2
Me
thocis o f
charact
er
i z i n g t he
p e r f ormance o f
radiometers and photometers [11 sowie uf d i e CIE-Publicat ionen No. 24
[21,
Wo. 27
[ 3 ] , und No. 43
141.
Rei den Begri f fsbest immungen sind d ie
ilngaben des I n te rna t iona len Wörterbuchs der L ich t techn ik [51 weitgehend
zugrunde gelegt.
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1 .2 SURFACE OF LUMINOUS INTENSITY DISTRIBUTION
The
surface
o f l u min ou s i n t e n s i t y d i s t r i b u t i o n
is
t h e
surface
f o r m e d
b y
t h e extremit ies o f a l l t h e r a d i u s v e c t o r s d raw n fro m a co m m o n o r ig in ,
t h e l e n g t h o f e a ch r a d i u s v e c t o r b e in g p r o p o r t i o n a l t o t h e l u m i n o u s i n t e n -
s i t y
of
t h e s o u r c e i n t h e c o r re s p on d i ng d i r e c t i o n .
1 . 3
LUMINOUS INTENSITY DISTRIBUTION
CURVE
The I iJm inous i n t e n s i t y d i s t r i b u t i o n c u r v e ( f o r a lam p
or
l i g h t f i t -
t i n g )
i s t h e
c u r v e , g e n e r a l l y p o l a r , w hic h r e p r e s e n t s t h e lu m in ou s i n t e n s i -
t y i n a p l a n e p a s s i n g t h r ou g h t h e s o u r c e ,
as
a f u n c t i o n o f t h e an g le m ea-
sured from soine
g i v e n d i r e c t i o n .
N o t e
:
a ) When t h e s o u r c e h a s
a
s ym m e tr ic a l l um in ou s i n t e n s i t y d i s t r i b u t i o n , t h e
b) When t h e r e f e r e n c e d i r e c t i o n is v e r t i c a l , a n g l e s a r e m ea su re d f r o m t h e
p l a n e
i s
g e n e r a l l y a m e r i d i a n p l a n e .
downward ver t ica l .
1.4
ISOCANDELA DIAGRAM
T h e i s o c a n d e l a d i a g r a m is t h e a r r a y o f i s o c a n d e l a c u r v e s . T he se are
curves
t r a c e d on an i m ag in a ry s p h e r e w i t h t h e s o u r c e a t
i t s
c e n t r e a nd
j o i n i n g
a l l t h e
p o i n t s c o r r e s p o n d i n g t o t h o s e d i r e c t i o n s i n w hic h t h e l u m i -
n ou s i n t e n s i t y is t h e
same, or
a
plane
p r o j e c t i o n
o f
t h i s c ur ve .
1.5 MEASURING F I E L D AND MEASURING-FIELD ANGLE I N LUMINANCE MEASUREMENTS[ 61
T he m e as u ri ng f i e l d o f a l u m i n a n c e
meter
is t h e t o t a l i t y
of
a l l p o i n t s
i n t h e external s p a c e t h a t r a d i a t e
i n t o
t h e a c c e p t a n c e
area
a n d a r e s e n s e d
by t h e d e t e c t o r a nd e v a l u a t e d by i t w i t h
a
d i r e c t i o n - d e p e n d e n t r e s p o n s i v i t y
o f a t
l eas t
10%
o f t h e maximum r e s p o n s i v i t y .
Note:
The m e as ur in g f i e l d
is
u s u a l l y c i r c u l a r .
a r e a l s o p o s s i h l e , h ow ever ( e . g . , t r a p e z o i d a l , r e c t a n g u l a r , q u a d r a t i c )
O t h e r f i x e d
or
v a r i a b l e s h a p e s
The m e e s u r i n g - f i e l d e n g l e tr is t he a n g l e u n d e r which t h e m e as ur in g f i e l d
a p p e a r s when v i ew e d f ro m t h e m e a s u r i n g p l a n e .
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1 .6
TERMS FOR
M E A S U R I N G INSTRUMENTS
1.6 .1 P H O T O M E T E R
A
p h o t o m e t e r
i s
a n i n s t r u m e n t
quant i t ies .
f o r
t h e m e a s u r e m e n t
o f
p h o t o m e t r i c
N o te :
P h o t o m e t r i c q u a n t i t i e s
are
q u a n t i t i e s t h a t c a n b e d e r i v e d fro m
r a d i o m e t r i c q u a n t i t i e s by m eans o f c e r t a i n c o n v en t io n s ( l a w o f
a d d i t i v i t y ,
V X
)
f u n c t i o n , d e f i n i t o n o f t h e u n i t o f l u m i no us i n t e n s i t y )
Dl
1 . 6 . 2 G O N I O P H O T O M E T E R
A g o n i o p h o t o m e t e r is
a
p h o t o m e t e r for t h e me as ur em en t o f t h e a n g u l a r
d e p e n d e n c e o f
a
p h o t o m e t r i c q u a n t i t y .
Note:
A
g o n i o p h o t o m e t e r
f o r
t h e m e a s u r e m e n t
o f
t h e s p a t i a l l u m i n ou s i n t e n s i t y
d i s t r i b u t i o n
i s
a l s o c a l l e d a l u m i n ou s i n t e n s i t y d i s t r i b u t i o n
p h o t o m e t e r .
A g o n i o p h o t o m e t e r f o r t h e m ea su re me nt o f t h e s p a t i a l l um i no us i n t e n s i t y
d i s t r i b u t i o n u s u a l l y c o n s i s t s o f a m e c h a n i c a l d e v i c e for t h e s u p p o r t a nd
p o s i t i o n i n g o f t h e l i g h t s o u r c e a n d t h e p h ot om e t er h e ad and o ne (o r m o r e ) -
o f t e n m o v e a b l e
-
p h ot om e t er h e a ds t o g e t h e r w i t h t h e necessary t r a n s d u c e r s
a n d r e a d o u t s as well as d e v i c e s f o r a c q u i r i n g a nd p r o c e s s i n g d a t a .
1 . 6 . 3 PHOTOM ETER
HEAD
A p h o t o m e t e r h e a d 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
f o r t h e s p e c t r a l e v a lu a t i o n (e.g., c o l o u r f i l t e r s ) or for
t h e
s p e c t r a l
d i s p e r s i o n e . g . , 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 t h e 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 w i n d o w s , l e n -
s e s , a p e r t u r e s . The l i g h t - s e n s i t i v e d e t e c t o r c o n v e r ts t h e i n c i d e n t l i g h t
i n t o a n e l e c t r i c a l q u a n t i t y .
1.6.4 ACCEPTANCE A R E A
T h e
a c c e p t a n c e a r e a
i s
t h e
area of
t h e p h o t o m e t e r head which
i s
re-
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 .
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-
~
CIE 70 87
006345
0003033 147
1 . 7 P H O T O M E T R I C C E N T R E (OF
A LAMP
O R L U M I N A I R E )
The
p h o t o m e t r i c c e n t r e
o f
a
l a m p or
l u m i n a i r e
is
t h e r e f e r e n c e p o i n t
fro m wh ic h t h e p h o t o m e t r i c d i s t a n c e la w i s a p p l i c a b l e ( s e e sec t ion 2 . 1 ) .
F o r
l a m p s t h e p h o t o m e t r i c c e n t r e c o r re s p o n d s
t o
t h e c e n t r e o f g r a v i t y o f
t h e l i g h t - e m i t t i n g a r e a . F o r l am ps w i th r e f l e c t o r s t h e ph o t om e t r ic c e n t r e
i s
s i t u a t e d a t t h e c e n t r e
o f
t h e
e x i t
a p e r t u r e .
F o r
l u m i n a i r e s
data
a b o u t
t h e p h o t o m e t r i c c e n t r e a r e c c n t a i n e d i n t h e T e c h n ic a l R e p o r t "P ho to m et ry of
L u m i n a i r e s " [ 81.
Yote :
For
t h e m e a s u r e m e n t
o f t h e
l u m i n o u s i n t e n s i t y d i s t r i b u t i o n t h e p h ot o -
metric cent re o f
t h e l i g h t s o u r c e s h o u ld l i e o n
t h e
c r o s s p o i n t
o f
t h e
a x e s o f the
g o n i o p h o t o m e t e r .
1 . 8
S T R A Y L I G H T
- -
S t r a y l i g h t is t h e p a r t o f t h e l u m in ou s
f l u x
i n c i d e n t o n and e v a l u a t e d
by t h e p ho t o m e t e r he a d t h a t d o e s n o t r e a c h t h e
measuring
a r e a of t h e p h o t o -
m e t er he ad i n a d i r e c t l i n e f ro in t h e l i g h t s o u r c e .
1.9 L L M I T I N G P H O TO M E TR IC D I S T A N C E--
The l i m i t i n g p h o t om e t r ic d i s t a n c e i s t h e a l l o w e d m inimum d i s t a n c e b e-
t w e e n L i g h t
source
a n d p h o t o m e t e r h e a d ,
For
w h ic h t h e m e a s u r i n g
e r ro r i s
smal ler t h a n t h e p e r m i t te d e r r o r .
2.
PRINCIPLES
OF
LWINOUS INTENSITY MEASUREMENTS
L um ino us i n t e n s i t i e s c an b e m ea s ur ed v i a
a measurement
of
the
i l l u m i -
n a n c e a n d c a l c u l a t i o n v ia the p h o t o m e t r i c d i s t a n c e
law,
o r
by
i n t e g r a t i o n
o f t h e lu m i na n c e. B oth p o s s i b i l i t i e s f o l lo w f ro m t h e b a s i c law of
p h o t o m e t r y .
2 . 1 P H O T O M E T R I C D I S T A N C E LAW
--
T he p h o t o m e t r i c d i s t a n c e lavJ allows o n e t o d e t e r m i n e
the
l u m i n o u s i n -
t e n s i t y a c c o r d i n g t o
I E
r2
/ ( c o s €2
80
(4 )
I L u m i n o u s i n t e n s i t y i n t h e d i r e c t i o n t o t h e a c ce p ta n c e a r e s
E
I l l u m i n a n c e on t h e a c c e p t a n c e a r e a
r D i s t a n c e be tw e en l i g h t s o u r c e a nd a c c e p t a n c e a r e a
E 2
Q O
s r
( u n i t s o l i d a n g l e )
A n g l e o f i n c id e n c e , m ea su re d r e l a t i v e t o t h e normal t o t h e
ac-
c e p t a n c e a r e a
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C I E 7 0 87 ï OObLL t 5 0003032
O ô 3
T h e q u a n t i t y 80
i s
u s e d i n a c c o r d a n c e w i t h t h e f o u r t h e d i t i o n of
t h e
C I E
v o ca b u l a ry ( i n p r e p a r a t i o n ) , w h ic h p e r m i t s
i ts
o p t i o n a l u s e . T h e re i s no
c o m p l e t e a g r e e m e n t
on
t h e n ee d t o
use
80,
w h ich may e q u a l l y well b e o m i t t e d
or r e p l a c e d by t h e nu m be r 1.
T h e E q u a t i o n
(4)
o n l y a p p l i e s
f o r
d i s t a n c e s
r
t h a t e xc ee d t h e l i m i t i n g
p h o t o m e t r i c d i s t a n c e .
m e a s u r i n g e r r o r d e p e n d s o n :
- t h e l a r g e s t d im e ns io n of t h e l i g h t s o u r c e
- t h e s p a t i a l an d d i r e c t i o n a l l u m in an ce d i s t r i b u t i o n o f t h e l i g h t s o u r c e
- t h e s p a t i a l an d d i r e c t i o n a l r e s p o n s i v i t y o f t h e a c c e p t an c e area of the
p h o t o m e t e r h e a d .
Y o t e
1:
For a c i r c u l a r e m i t t i n g a r e a w i t h c o n s t a n t l u m in an ce ( l a m b e r t i a n r a d i a -
t o r ) a n d a c i r c u l a r r e c e i v i n g a r e a t h e l i m i t i n g p ho to m e t r i c d i s t a n c e r
i s t ak e n a s 10 times (5
times)
t h e d i a m e te r o f ' t h e l a r g e r o f t h e
two
a r e a s .
I n
t h i s case t h e e r r o r
o f
I i n t h e d i r e c t i o n o f t h e a x i s
o f t h e
d i s k i n t h e c a l c u l a t i o n a c c o r d i n g t o t h e p h o to m e t r ic d i s t a n c e
law
is
less t h a n 0,5 X
(1
X).
N o t e 2:
F o r n ar ro w l um in ou s i n t e n s i t y d i s t r i b u t i o n s t h e l i m i t i n g p h o t o m e t r i c
d i s t a n c e is g r e a t e r t h a n f o r a L a m b er t i a n r a d i a t o r [ 9,101.
N o t e
3 :
When c a l c u l a t i n g t h e l u m i no us i n t e n s i t y a c c o r d i n g t o e q u a t i o n
(4) it
s h ou ld be a s c e r t a i n e d , i f n e c e s s a r y
by
m ea ns of m e a s u r e m e nt s a t
d i f f e r e n t d i s t a n c e s , w h e th er t h e l i m i t i n g ph o t o m e tr ic d i s t a n c e is
e x c e e d e d . For g o n i op h o t om e t e r s w i t h s t a t i o n a r y p h ot o m e te r h e a ds
f o r
w hi ch t h e m ea s ur in g d i s t a n c e
i s smaller
t h a n t h e l i m i t i n g p h o to m e t r i c
d i s t a n c e , t h e m e a su ri ng d i s t a n c e can b e e x t e n d e d by t h e u s e
of
a
s u f f i c i e n t l y l a r g e d e f l e c t i n g m i r ro r . The p o l a r i z a t i o n
o f
t h e l i g h t by
t h e d e f l e c t in g m i r r o r a s well a s t h e s p e c t r a l r e f l e c t a n c e of t h e
d e f l e c t i n g m i r r o r m ust be t a k e n i n t o ac c o u n t.
N o t e 4 :
When t h e l u m in o u s i n t e n s i t y i s d e r i v e d a c c o r d i n g t o e q u a t i o n 4) t is
i m p o r t a n t t o l i m i t t h e i n c i d e n c e of s t r a y l i g h t o n t h e ph o to m e te r he a d
by means o f b a f f l e s b e tw e en t h e l i g h t s o u r c e a n d t h e ph o to m e te r he ad .
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4 1 1
p a r t s o f
t h e background o f t h e
l i g h t s o u r c e t h a t a r e v i s i b l e f r om
t h e
m e a s u r i n g a r e a
o f
t h e p h o t o m e t e r head s h o u l d b e a s black a s p o s s i b l e
(113. 4s l a rge a d i s t a n c e a s p o s s i b l e s h o u l d be k e p t b e t w e e n t h e l i g h t
source
a n d the b a c k g r o u n d ( F i g .
I.).
BAFFLES
/ /
\
BLACK
BACKGROUND
I
LIGHT
SOURCE
F i g . 1 R e d u c t i o n o f s t r a y l i g h t i n l u m in ou s i n t e n s i t y m ea su re me nt s
2.2
L U M I N A N C E I N T E G R A T I O N
Luminous
i n t e n s i t y c a n be d e t e r m i n e d by means o f l u m i n a n c e i n t e g r a -
t i o n :
A l
e m i t t i n g a r e a
d
A l
e l e m e n t
o f
t h e e m i t t i n g a r e a
L k 1 )
l u m i n a n c e
o f
t h e a r e a e l em e nt
c o s € 1 5 )
dA, i n t h e d i r e c t i o n i n wh ic h
t h e l um in ou s i n t e n s i t y i s t o be d e t e r m i n e d
e m i t t i n g a n g l e
o f
t h e a r e a e l e m e n t dA, b e t w ee n i ts a r e a n o r m a l
and t h e d i r e c t i o n
f o r
w hi ch t h e lu m in ou s i n t e n s i t y
i s
t o b e
d e t e r m i n e d .
€ 1
3 , TYPES
OF
PHOTOMETER HEADS
D e p e n d i n g
on
t h e t h e o r e t i c a l r e l a t i o n s h i p u s e d f o r t h e d e t e r m i n a t i o n
of
t h e lu m in ou s i n t e n s i t y ( e q u a t i o n
( 4 )
o r
5 ) ) , t h e r e a r e two t y p e s o f p h o t o -
meter h e a d s i n use
in
g o n i o p h o t o m e t e r s .
3 . 1 PHOTOMETER H E A D FOR MEASURING ILLUMINANCE
F o r t h e d e t e r m i n a t i o n o f t h e l u m i n o u s i n t e n s i t y a c c o r d in g t o e q u a t i o n
( 4 )
a
p h o t o m e t e r h e a d for t h e m e a s u r e m e n t
o f
illuminance m u s t b e em p lo y ed .
S u c h a p h o t o m e t e r h e a d m u s t comply
with t h e
f o l l o w i n g r e q u i r e m e n t s
[
1,6 ]
:
6
pyright International Commission on Illuminationovided by IHS under license with CIE
Not for Resalereproduction or networking permitted without license from IHS
- - ` ` ` , , - ` - ` , ,
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` ,
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` - - -
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17/54
- good
f i t of
t h e r e l a t i v e
s p e c t r a l r e s p o n s i v i t y t o t h e
V h
f u n c t i o n
-
l i n e a r i t y ( e r r o r
f 3 )
-
-
i n de p en d e nc e fro m t h e a m b ie n t t e m p e r a t u r e ( t e m p e r a tu r e c o e f f i c i e n t
a )
- a s small a s o l i d a n g l e
a s
p o s s i b l e f o r t h e a c c e p t a n c e a r e a o f t h e p ho to -
( e r r o r f i
1
low
f a t i g u e ( e r r o r f5
1
meter
head a s s e e n froin t h e p h o t o m e t r i c c e n t r e .
UGHT
%URCE
T h e t e r m i n o l o g y f o r t h e
er rors
f i t o
f 5
and
a
c l a s s i f i c a t i o n of i l l u m i n a n ce
meters have
been
c o m p i l e d
by
t h e C I E
[6 ]
~ - - - - ---- ACCEPTANCE
AREA
-,--, - - -
-
--
OR APERTURE
(DIAMETER a )
r
L f 4
3.2
PHOTOMETER
HEAD FOR L U M I N A N C E I N T E G R A T I O N
3.2.1 CDNSTRUCTION
3 . 2 .1 . 1 P h o t o m e t e r h e a d w i t h
l ens
[U]
A
p h o to m e te r he ad f o r lu m i na n ce i n t e g r a t i o n
by
means
o f
a l e n s
c o n s i s t s o f
a
l e n s w i t h a d i a m e t e r l a r g e r t ha n t h e l i g h t s o u r c e an d a de-
t e c t o r ( i n c l u d i n g f i l t e r
f o r V ( h )
c o r r e c t i o n ) t h a t
is
p o s i t i o n e d b e h i n d
a
d ia ph ra gm a t t h e f o c a l p o i n t o f
t h e
l e n s ( a l s o c a l l e d t h e f i e l d s t o p )
( F i g . 2 ) .
a
=
2
a r c t a n ( a / î f )
The m e a su r in g f i e l d a n g l e
a
of s u c h a p h o t o m e t e r h e a d is
(61
f
f o c a l l e n g t h o f l e n s
a
d i a m e t e r
o f
m e a s u r i n g - f i e l d s t o p
F i g . 2: Pho t om e t e r head w i t h lens f o r l um i no u s i n t e n s i t y m e a su re m en ts
by
means
o f
l u m i n a n c e i n t e g r a t i o n
T he l a r g e s t d i a m e t er
D
o f a l i g h t s o u r ce t h a t c an be m easur ed w i t h a pho t o -
meter
head
f o r
l u m i n an c e i n t e g r a t i o n by m ea ns
o f
a l e n s
is
g i v e n
b y
D
d
-
r
9 a / f
7
1
D l a r g e s t
p e r m i s s i b l e e x t e n t of
t h e
l i g h t
source
d
diameter
of
t h e
l e n s
r dis tance b etw ee n l e n s a nd l i g h t s o u r c e
7
pyright International Commission on Illuminationovided by IHS under license with CIE
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~
CIE
70 8 7 9006345 0003035 892
The
n e a s u r e m e n t s c a n b e made a t
an
a r b i t r a r y d i s t a n c e
r
b e t w e e n l i g h t
s o u r c e
a n d l e n s as l o n g as t h e c o n d i t i o n a c c o rd i ng t o e q u a t i o n ( 7 ) and
c o n d i t i o n s r e g a r d i n g t h e l i m i t i n g p h o to m e t r i c d i s t a n c e ( l i m i t i n g t h e r a t i o
?/r
t o a
maximum value)
are
s a t i s f i e d (see
a l s o 3 . 2 . 3 ) .
3 . 2 . 1 . 2
P h o to m et er hea d w i t h p a r a l l e l o r i e n t e d o p t i c s
I n s t e a d o f a s i n g l e l e n s i t is a l s o p o s s i b l e
to
use s e v e r a l l e n -
s e s t h a t are p o s i t i o n e d i m m ed ia te ly n e x t t o e a c h o t h e r . By m ean s o f su ch
EI^
a r r a n g e m e n t
i t is
p o s s i b l e
t o
m e as ur e l i g h t s o u r c e s w i th l a r g e r e m i t t i n g
a r e a s .
A
p ho to m et er h ea d w i t h p a r a l l e l o r i e n t e d lenses
can
a l s o b e c o n s t r u c t e d
i n s u c h a
way
t h a t t h e lenses
are merely
p o s i t i o n e d n ex t t o each o t h e r
i n a
s i n g i e
l i n e .
T h i s row
of l e n s e s c a n
be
moved or t i l t e d i n a p l a n e
i io rm a l t o t h e m e a s u r i ng d i r e c t i o n , a nd t h e l u m in a nc e i n t e g r a t i o n (summa-
t i o n ) p e r p e n d i c u la r t o t h e row of lenses must b e p e r f o r m e d n u m e r i c a l l y
[131.
3 . 2 . 1 . 3
P h o t o m e t e r head w i t h t u b e s [ 14 , 15 1
A
p h o t o m e t e r h e a d for l um i n an c e i n t e g r a t i o n ca n a lso be c o n s t r u c -
t e d by m eans of p a r a l l e l t u b e s f o ll o w e d by a l i g h t c o l l e c t i n g d e v i c e a nd a
p h o t o - e l e c t r i c d e t e c t o r ( w i th V h ) r e s p o n s e ) .
F i g u r e
3
sh o w s su ch
an
ar-
r an ge m en t, i n w hic h t h e l i g h t - c o l l e c t i n g d e v i c e
is
r e a l i z e d
by
means
of a
s p h e r i c a l d e v i c e l o c a t e d b e h i nd t h e t u b e s a nd with a n e f f e c t similar t o a n
i n t e g r a t i n g s p h e r e . The d e t e c t o r c an
be
l o c a t e d a t t h e s i d e of t h e s p h e r i -
c a l d ev ic e . A s p a t i a l l y c o n s t a n t e v a l u a t i o n
of the
l u m i n a n c e
can
be
a c h i e v e d by m ea ns of a p e r t u r e s i n f r o n t
o f
t h e d e t e c t o r .
-
Il
I
I
l i l i
I
Il
r
I
PHOTOMULTI
PUER
CAP
OFTHE
SPHERE
J i g . 3 : P h o t o m e t e r h e a d w i t h t u b e s f o r l u m i n a n c e i n t e g r a t i o n
8
pyright International Commission on Illumination
ovided by IHS under license with CIE
Not for Resalereproduction or networking permitted without license from IHS
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C I E 7 0 87 900b145 O003036 7 2 9
The r e l a t i v e s p e c t r a l r e s p o n s i v i t y
o f such
a photometer h e a d
is
d e t e r m i n e d
d e c i s i v e l y by t h e s p e c t r a l r e f l e c t a n c e
of t h e
i n t e r i o r p a i n t of t h e spheri-
c a l
c o l l e c t i n g d e v ic e . P o l l u t i o n o f t h e p a i n t - e v e n if i t i s
n o n - s e l e c t i v e - c a n l e a d t o
a
c h a n g e i n t h e r e l a t i v e s p e c t r a l r e s p o n s i v i t y
a n d
i n
the
a b s o l u t e r e s p o n s i v i t y
o f
t h e d e v i c e
a s
a w h o le .
Note:
A test
o f
t h e r e l a t i v e s p e c t r a l r e s p o n s i v i t y of t h e w h o le m e a s u r i n g h e a d
is n o t p o s s i b l e
i n
p r a c t i c e .
Figure 4 s h o w s a n o t h e r a r r a n g e m e n t o f
t h e
p h o t o m e t e r h e a d w i t h p a r a l l e l
o r i e n t e d t u b e s ,
f o r w h i c h a h i g h u n i f o r m i t y
o f
t h e s p a t i a l r e s p o n s i v i ty c a n
b e a c h i e v e d a n d w h i c h h a s a
s t a b l e a n d
m e as ur ab le s p e c t r a l r e s p o n s i v i t y
[
161
TUBES
HOUSING
ETECTOR
F i g
4:
P h o t o m e t e r h e a d f o r l u m i n a n c e i n t e g r a t i o n
The d i s t a n c e b etw ee n t h e l i g h t s o u r c e a nd t h e a c c e p t a n c e a r e a o f t h e p h o t o -
meter h ea d c a n i n f l u e n c e t h e r e s u l t
o f
t h e m e a s u r e m e n t .
I n
o r d e r c o m p l e t e l y
t o
c o ve r t h e e m i t t i n g a r e a o f
a
l i g h t s o u r c e , t h e
smallest d i s t a n c e r m i n between the a c c e p t a n c e a r e a a nd t h e l i g h t source
s h o u l d c o m p l y w i t h (Fig . 5)
where
R
d
f
m i n
d i s t a n c e be tw ee n a d j a c e n t tubes i n tube p l a t e
tube d i a m e t e r
thickness
o f
t u b e
plate
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pyright International Commission on Illumination
ovided by IHS under license with CIE
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` ,
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-
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C I E
7 0
157 9006345 0003037 665
For
mechanical
r e a s o n s , r,,-,in must a l s o e x c ee d h a l f o f t h e l a r g e s t e x t e n t
c9)
o f t h e L i g h t s o u r c e . Thus a c o n s e r v a t i v e l i m i t fo r
the
l a r g e s t d i i n e n -
s i o n
(Dma, o f t h e l a r g e s t l i g h t s o u r c e t h a t may be measu r ed
w i t h
t h e i n -
s t r u m e n t w o uld b e
se t
by r e q u i r i n g t h e sum o f rmin and Dmax /2 t o
e q u a l
t h e f i x e d r ad ius o f r o t a t i o n
( r ) o f
t h e g o n i o p h o t o m e t e r . From t h i s c o n d i -
t i o n ilmax
a n be s p e c i f i e d
a s
Dmax
rinin
a c c o rd i n g t o e q u a t i o n
( 8 )
l a r g e s t e x t e n t
o f t h e
l a r g e s t p e r m i s s i b l e l i g h t s ou r c e
P
g i v e n r a d i u s o f r o t a t i o n
f o r a
p a r t i c u l a r g o n i o p h o t o m e t e r
LIGHT
EMITTING AREA
HORIZONTAL
PROJECTION
TUBE PUE
i
VERTICAL
PR03
ECTION
O
F i g .
5 :
D i m e n s i o n s
fo r
photometer h e a d
f o r
l um i na nc e i n t e g r a t i o n w i t h
t u b e p l a t e
pyright International Commission on Illuminationovided by IHS under license with CIE
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C I E 70
87
M
7006345
0003038 5 T L
T h e
minimum diameter
6
o f
t h e
acceptance area
of t h e
photometer head should
be
It
should be ascer ta ined whether the r es ul t i s independent
o f
the d is tance
between l i g h t source and acceptance area.
3 . 2 . 2
INFLUENCE OF INHOMOGENEOUS
ILLUMINATION
[
2,3,15]
A s p a t i a l l y inhomogeneous luminance o f th e l i g h t source can cause measuring
e r ro rs ,
i f
t h e r e s p o n s i v i t y
o f
the photometer head i s
n o t
un i fo rm over the
acceptance area.
The
measur ing error
w i l l
depend on the luminance d is t r ibu t ion o f
t h e
l i g h t
sou rce, t he s i ze o f t h e source and th e magn itude and d i s t r i b u t i o n o f
respons iv i t y d i f f e rences over the acceptance area.
I f a
ca l i b r a t io n i s pe rformed, t he measur ing e r ro r
w i l l
depend on
t h e
r e l a -
tive p r o p e r t i e s o f t h e c a l i b r a t i o n s o ur ce and t h e sourc e t o be measured as
well
as on t h e p o s i t i o n o f t h e s o u r c e s r e l a t i v e t o t h e acceptance area.
I f possib le the ca l ibrat ion source and the source to be measured should be
p laced
i n
the same posi t ion.
To
prov ide
a
b a s i s
f o r
t he eva lua t ion o f poss ib le measu r ing
e r ro r s
t h e
respon s iv i ty d i s t r i bu t i on over the acceptance area should be de termined.
This may be done by b r i n g i n g th e photometer head t o a h o r iz o n t a l p o s i t i o n
with the normal t o t he acceptance area p o i n t i n g upwards and moving
a
l i g h t
source
i n
a ho r i zo n t a l p lane a t a d is tance g rea te r t han the
m i n i m u m
d i s -
tance
rmin
(see equat ion
8)
i n such a way that i t covers success ive ly the
whole area above the photometer head.
T h e
l igh t source shou ld have
an
approx imate ly constan t luminous in tens i ty
d i s t r i b u t i o n i n d i r e c t i o n s c l o s e t o t h e no rmal a nd i t s e m i t t i n g a re a s h ou ld
not exceed
1/10 o f
the acceptance area
or 10
cm2 (whichever
i s
smal le r ) .
A
100 W
f r os t ed incandescent
lamp
may be used.
The
read ings o f
t h e
photometer f o r t h e v a r i o u s p o s i t i o n s o f
t h e
lamp may be
used t o c a l c u la t e t h e
e r r o r
f g by inhomegeneous i l l um in a t io n re levan t t o
t h e
in tended use of
t h e
photometer.
A worst-case e r r o r i s obta ined i f f g i s determined
as
t h e la rgest percen-
tage d i f ference between readings.
1 1
pyright International Commission on Illuminationovided by IHS under license with CIE
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0003039
438
Y minimum reading
Y v a x
maximum r e a d i n g
I f t h e
p h o t o m e t e r i s t o be u s e d f o r t h e m e a s u re m e nt o f compact l i g h t
sources, fg
s h o u l d
h e determiiieá a s t h e l s r g e s t p e r c e n ta g e d i f f e r e n c e o f
,s:i
t h e
mean
o f
t h e
r e a d i n g s
t a k e n
a l o n g t h e c i r c u m f e r e n c e
of
any
c i r c l e
cor i ta ined
w i t h i n t h e a c c e p ta n c e a r e a a nd c e n t r e d on t h e m i d p o i nt of t h e
8 i - w and (b ) t h e m i d p o i n t reading
Y O nii d po
i n r ea d i n
g
Au
a n g u l a r
step size of readings
i n d e g r e e s
(1
Y,),,, maximum o f t h e mean r e a d i n g a l o n g a
c i r c l e
Y, ,i, minimum
o f
t h e
mean
r e a d i n g a l o n g a c i r c l e
I f t h e p h o t o m e t e r i s t o b e u s e d f o r t h e m e a s u r e m e n t o f L i n e a r L i g h t
s o u r c e s , f g s h o u l d
be
d e t e r m i n e d a s
the
l a r g e s t p e r ce n t a g e d i f f e r e n c e
o f
t h e mean r e a d i n g a l o n g an y d i a m e t e r s o f t h e c i rc les a nd t h e m ean r e a d i n g
a l o n g t h e c i r c l e diameter parallel t o t h e h o r i z o n t a l a x i s o f t h e p h o t o -
metsr.
I f t h e p h o t o m e t e r i s to
be
used f o r b o t h c o m p a c t a n d Linear l i g h t sources
t h e l a rger
o f
t h e above er rors s h o u l d
be
s t a t e d .
R e a d i n g s s h o u l d
be
t a k e n a t
t he m a l l e s t p o s s i b l e i nc re m en ts i n circle d i a -
meters a nd a n g u l a r d i s t a n c e b e tw e en d i a m e t e r s . in t h e d e t e r m i n a t i o n of f g
p e r c e n t a g e d i f f e r e n c e s f o r i n c r e m e n t s
o f
c i rc le d i a m e t e r s of 20 cm and i n -
c r e m e n t s
o f
a n g u l a r d i s t a n c e
of 5
o s h o u l d
be
c a l c u l a t e d .
3 + Z .
3
INFI-IJENCE OF THE MEASURING-FIELD
ANGLE
When t h e l um in ou s i n t e n s i t y is d e t e r m i n e d by a n i l l u m i n a n c e m e a s u r e -
m e n t
t h e l imi t ing p h o t o m e t r i c d i s t a n c e r d e t e r m i n e s a maxim um v a l u e for t h e
r a t i o D/r (D b e i n g t h e l a r g e s t e x t e n t o f t h e l i g h t
source).
T h i s l i m i t i n g
r a t i o m i x t
a l s o
be
t a k e n
i n t o
a c c o u n t i f t h e l um in ou s i n t e n s i t y is d e t e r -
m i n e d v i a
a
h m i n a n c e m e a s i i r e t n e n t . F o r a p h o t o m e te r h ea d w i t h l e n s t h i s
means
-< t 4 e as u r in g - f i e ld a n g l e a c c o r d i n g t o e q u a t i o n 6 )
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C I E i 0 87 9006345 0003041 096
4 . 2
B P L B N E C
See
Fig .
71
The t o t a l i t y of B - p l a n e s is t h e
group
o f p l a n e s fo r which the l i n e
o f
i n t e r s e c t i o n goes t h r o u g h t h e p h o t o m e t r i c c e n t r e a n d
is parallel t o t h e
assumed a x i s
o f
t h e l i g h t
source
and
i s
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 o f
t h e
A - p l a n e s .
Note :
The system of B -p lan es is c ou pl ed r i g i d l y t o t h e l i g h t
source
and
f o l -
lows i t s
t i l t
i f t h e
light source
is t i l t e d .
LINE
OF
NTERSECTION
AND
'AXIS OF LIGHT
SOURCE
F i g . 7: 6 - p l a n e s
4 . 3
C-PLANES
( S e e F i g .
8 )
The
t o t a l i t y
of
C - p l a n e s i s t h e g r o u p o f planes Por w hich 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 ver t ica l l i n e t h r ou g h t h e p h o t o m e t r ic c e n t r e .
Wote :
The
s y s t e m
of
C - p l a n e s
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
space
a n d
does
n o t
f o l l o w
8 t i l t i n t h e l i g h t s o u r c e . The l i n e
o f
i n t e r s e c t i o n of C-
p l a n e s is o n l y p e r p e n d i c u l a r t o t h e l i n e s o f i n t e r s e c t i o n of t h e A-
and
8 - p l a n e s
f o r
zero
t i l t
6
= O)
of
t h e
l i g h t s o u r c e .
I n some c a se 5 t h e t o t a l i t y
o f
C - p l a n e s
is also
referred t o a s t h e
group
of
p L a n es w ho se l i n e
o f
i n t e r s e c t i o n is t h e l i n e o f i n t e r s e c t i o n of
A o -
a n d
B o - p l a n e s ( s e e F i g .
9 ) .
I n t h a t
cace
t h e system
o f
C - p l a n e s i s
a l s o
r i g i d -
l y
c o u p l e d
to the
l i g h t
source
as is t h e case f o r t h e A- a n d ß - p l a n e s ) .
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~
C I E 70 87
900bL45
00030Y2 T22
AXIS OF
LIGHT
SOURCE
‘270
(PERPENDICULAR TO
MEASURING PLANES)
F i g .
8:
C-planes
( 6
t i l t
a n g l e o f
l u m i n a i r e )
LINE OF INTERSE
(OF A,-
ANO
Bo -
A X I S
OF
LIGHT SOURCE
:CTI
PL
ON
AN€)
F i g . 9:
C-planes w i t h r i g i d
c o u p l i n g t o t h e
l i g h t
s o u r c e
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C I E i 0 8 7 e 9006145
0003043 969
4.4 CONICAL SURFACE5 (F ig .
1 0 )
For some
g o n i o p h o t o m e t e r s
i t
is c o n v e n i e n t
t o
m a s u r e
t h e
l u m i n o u s
i n -
t e n s t y d i s t r i b u t i o n
curves
a t c o n s t a n t
po la r
a n g l e s
and t o
d e s c r i b e
t he
r e s u l t s
as
c u r v e s on c o n i c a l s u r f a c e s . The a x i s
o f t h e
c o n e c o r r e s p o n d s t o
t he
l i n e
o f
i n t e r s e c t i o n o f t h e C - p l a n e s .
LIGHT
SOURCE
LUMINOUS INTENSITY
DISTRIBUTION
- C I
J
/
F i g .
1 0 : Conical
surfaces
4.5 SYMBOLS FOR PLANE
ANGLES
The t i l t a n g l e s o f p l a n e s a r e d e s i g n a t e d by a n i n d e x , T he
t i l t
a n g l e s
o f the A-
and
ß - pl a ne s a r e ta k e n from -180
o
t h r o u g h O
o to
1 8 0 O , t h o s e o f
t h e C - p l a n e s f r o m
O o
t o
360 o
( s e m i p l a n e s ) . T he o p e n i n g
a n g l e
o f t h e
conica l
surfaces is m €?aS iJred r e l a t i v e
to
t h e l i n e o f i n t e r s e c t i o n o f t h e
C - p l a n e s .
T he f o l l o w i n g s y m b o l s a re i i sed
( f o r
a n g l e s y m b o l s see F i g s .
6-10):
-
t h e a n g l e s
i n
t h e A -p la n e h a v e t h e s ym b o l
a
a n d a r a m e a s ur ed
f rom t h e
l ine 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 o f t h e
A-
p l a n e s
-
t h e
a n g l e s i n t h e B-planes h a v e t h e s y m b ol
ß and
are m e a s u r e d
f rom the
l ine p e r p e n d i c u l a r t a t h e l ine of i n t e r s e c t i o n
o f
t h e B - p l a n e s
- t h e a n g l e s i n t h e C - pl an e h a v e t h e
symbol
y
a n d a r e m e a su r ed
from
t h e
line o f i n t e r s e c t i o n o f t h e C - p la ne s i n t h e d ow nw ard d i r e c t i o n
- t h e a n g l e s on t h e c o n i c a l s u r f a c e s h av e t h e s y m b o l C a n d a re m e a s u r e d
f r o m
t h e
C o - p l a n e .
The t i l t angles o f t h e p l a n e s a re a d d e d as i n d i c e s t o t h e r e l e v a n t p l a n e s .
I b
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Not for Resalereproduction or networking permitted without license from IHS
- - ` ` ` , , - ` - ` , ,
` , ,
` ,
` , ,
` - - -
-
8/9/2019 CIE 70-1987
27/54
~ ~~~~~~
CIE
70
87 7 0 0 6 3 4 5
0003044 B T 5
Sys t em
A-p
1
n e s
B - p l a n e s
C -p 1
n e s
C o n i c a l
surfaces
4 6
RELATIONSHIPS
A ng le i n t h e p l a n e T i l t a n g l e
o f
p l a n e
a
A
ß
B
Y
C
C
Y
A c e r t a i n d i r e c t i o n i n e a c h system o f p l a n e s i s c h a r a c t e r i z e d
by
t d o
a n g l e s :
T i l t
a n g l e
of
p l a n e ]
-
a n a n g l e
i n
o n e p l a n e
o r
c o n i c a l s u r f a c e
A , a
C , Y
A , a
-
a n d a n g l e f o r t h e
t i l t o f
t h e
p l a n e
o r
c o n i c a l
sur face.
t a n
A
= t a n
ß / c o s B
t a n
C =
s i n
B / t g 3
t a n
A
= c o s C . t g Y
T a b l e
1
shows
t h e
ang l e sym bo l s com m onl y
used
i n t h e v a r i o u s
systems
o f
p l a n e s .
T A B L E
1
A n g l e s y m b o l s
T he c o n v e r s i o n e q u a t i o n s
l i s t e d
i n T a b le 2
h o l d
f o r
t h e
a n g l e s i n T a b le 1.
T A B L E
2
C o n v e rs io n e q u a t i o n s
f o r systems o f
p l a n e s
I
i r e c t i o n
A n gle i n t h e p l a n e
s i n
ß
= s i n A
.
cos a
cos y = cos A
.
cos
a
si n a
I i n
B
.
c o s
ß
cos
Y =
COS
B
.
C O S
B
si n a =
s i n C .
s i n
Y
s i n i3
= c o s C
.
s i n
y
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C I E 7 0 8 7
9006345 0003045
733
5. GONIOPHOTOMETER
WITH
FACILITY
FOR TURNING
THE L IGHT URCE [2,4,18]
5 . 1 PRINCIPL E
I n t h e s e g on io ph o t or ne te rs t h e l i g h t
source
i s t u r n e d a r o u n d
a
v e r t i c a l
a s
well a s a h o r i z o n t a l ax i s .
T h e
p h o t o m e t e r h e a d is f i x e d , Accurate re
sul ts
f o r the l u m in o u s i n t e n s i t y d i s t r i b u t i o n w i t h t h i s t y p e of g o n i o p h o t o -
meter
were
o n l y o b t a in e d f o r l i g h t s o u r c e s i n w hich
t h e
l u m i n o u s i n t e n s i t y
d i s t r i b u t i o n
is
i n d e p e n d e n t o f o r i e n t a t i o n and t e m p e r a t u r e .
N o t e 1 :
For m e a s u r e m e n t s
o f
the l u min ou s i n t e n s i t y d i s t r i b u t i o n o f f l u o r e s c e n t
l a m p s a nd l u m i n a i r e s w i t h f l u o r e s c e n t l am ps t h i s t y p e o f g o n i o p h o t o m e t e r
c a n
be
u s e d p r o v i d e d tha t f o r p o s i t i o n s o f t h e l i g h t s o u r c e d i f f e r i n g
f ro in t h e no rm a l b u r n i n g p o s i t i o n t.he l um in ou s i n t e n s i t y i n each d i r e c -
t i o n
is h e l d c o n s t a n t by m ea ns o f
an
a u x i l i a r y d e t e c t o r
o r
t h a t t h e
ap-
2 r o p r i a t e c o r r e c t i o n f a c t o r s
are
a p p l i e d ( s e e s e c t i o n 5 . 4 ) .
Y o t e 2:
The o p t i c a l d i s t a n c e b etw een l i g h t
s o u r c e a nd p h o t om e t e r h e ad c a n
be
i n -
c r e a s e d by t h e u s e
o f
a d e f l e c t i o n
mir r o r
mounted
at
t h e f a r wall
o f
t h e
m e a s u r i n g room, S e l e c t i v e r e f l e c t i o n a n d p o l a r i z a t i o n by t h e m i r r o r
m u s t
be
t a k e n i n t o a c c o un t .
5.2 APPLICATION
. G o n io p ho t om e t er s w i th a f a c i l i t y for t u r n i n g t h e l i g h t s o u r c e s ho u ld
o n l y be u s e d t o m ea s ur e i n c a n d e s c e n t l a m ps arid f l u o r e s c e n t l a m p s
or lumi-
n a i r e s f i t t e d w i t h t h e s e l am p s. T h e se g o n i o p h o t o m e t e r s a r e t h e most ad v an -
t a g e o u s t y p e r e g a r d i n g c o n s t r u c t i o n an d p r i c e . They a r e u s u a l l y u se d f o r
t h e d e t e r m i n a t i o n of t h e l um in ou s i n t e n s i t y a c c o r d in g t o t h e p h o t o m e t r i c
d i s t a n c e law. T h e u se of an a u x i l i a r y d e t e c t o r ( s e c t i o n 5.4) is u s u a l l y
r e q u i r e d
5 . 3
C O N S T R U C T I O N
PRINCIPLES
T h e r e
are
t h r e e t y p e s of g o n io p h o t om e te r s w i t h f a c i l i t i e s f o r t u r n i n g
t h e
l i g h t
s ou rc e :
Type 1 F i x e d h o r i z o n t a l axis a n d a m ov eab le a x i s p e r p e n d i c u l a r t o t h e
f i x e d h o r i z o n t a l a x i s
( F i g .
i l ) [ i 9 ] . M e a s u r e m e n t s are made in
t h e A- or B -p lan es , w h en the l i g h t s o u r c e
is
t u r n e d a r o u n d t h e
h o r i z o n t a l
axis and t h e
s e c o n d a x i s is i n
a
f i x e d p o s i t i o n .
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~~ ~~~ ~
CIE 7 0 ô 7
111
9006345 O003046 678
111
F i g . 11: G o n io ph o t om e te r w i th f a c i l i t y f o r t u r n i n g
t h e
l i g h t source, t y p e
1.
Type 2 F i x e d ve r t i ca l a x i s , m o v e a b l e h o r i z o n t a l a x i s ( F i g . 1 2 . Meacure-
m e n t s are m ade i n the A- o r B - p l a n e s .
\
.-o
PHOTOMETER
F i g .
12:
G o ni op ho to m et er w i t h f a c i l i t y f o r t u r n i n g t h e l i g h t s o u r c e , t y p e
2.
5.4
A U X I L I A R Y
DETECTORS
[
2 , 3 ]
L i g h t
sources
f o r which t h e ( a b s o l u t e ) l u m i no us i n t e n s i t y d i s t r i b u t i o n
c h a n g e s w i t h
a
c h a n g e i n b u r n i n g p o s i t i o n b u t n o t t h e
r e l a t ive
l u m i n o u s
i n t e n s i t y d i s t r i b u t i o n
(e.g.,
f l u o r e s c e n t l a m p s or l u m i n a i r e s w i t h
f l u o r e s c e n t l a m p s ) c a n b e m e a s ur e d w i t h a g o n i o p h o t o m e t e r
i n
w h i c h t h e
l i g h t s o u r c e
is
t u r n e d i f t h e m e a s u r e m e n t s a r e c o r r e c t e d by m ea ns of a n
a u x i l i a r y d e t e c t o r . For p r e c i s i o n m e a s u r e m e n t s
t h i s
method i s no t r e c o m -
mended.
4n
i l l u m i n a n c e
meter
w i t h
a
s e p a r a t e p h o t o m e t e r he ad c an be
u s e d
as r e f e r e n c e d e t e c t o r . The a u x i l i a r y d e t e c t o r m ust
b e
f i x e d t o t h e l i g h t
s o u r c e ,
so
t h a t i t
f o l l o w s
i t s
movements .
I t
s h ou l d p r e f e r a b l y b e i l i u -
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~
CIE 70 87
9006345 O003047
504
?yDe 3 :
F i x e d v e r t i c a l axi s ,
m c v e a b l e
h o r i z a r i t a l a x i s >:Fig. 13,, Measure-
:nentc a r e
made i n t h e C-planes
s r
c o n i c a l
surFaces. Type
3
s
e q u i v a l r n t
Is0
t y p e 2 i f t h e l i g h t
s o u r c e is
t d r n e d by ?U degrees.
A
PHOTOMETER
HEAD
a
-=O
F i g .
1 3 :
G o n i o p h o t o m e t e r w i t h f a c i l i t y f o r t u r n i n g t h e l i g h t s o u r c e , t y p e
3 .
i n i n a t e d by a l l parts
o f
t h e e m i t t i n g area a nd s h o u l d n o t m ask t h e i l l u m i n a -
t i o n by t h e l i g h t s o u r c e on t h e p h o t o m e te r h e ad u s ed f o r m e a su r in g t h e l u -
m i n o u s i n t e n s i t y .
T he o n l y s t r i n g e n t re q u i r e m e n t s on t h e auxiliary d e t e c t o r a r e f o r small
fa-
t i g u e and d r i f t pa r am e t er s .
The
r e s t o f the
p a r am e t e rs c h a r a c t e r i z i n g
the
p r o p e r t i e s of i l l u m i n a n ce
meters
a r e
o f
l e s s i m p o r t a n c e .
F o r
the
m ea su re me nt o f t h e l um i no u s i n t e n s i t y d i s t r i b u t i o n on e
has
t o ob-
t a i n t h e r e a d i n g on t h e a u x i l i a r y d e t e c t o r i n t h e n o r i n a l b u r n i n g p o s i t i o n
o f t h e l i g h t s o u r c e . On t u r n i n g
t h e
l i g h t s o u r c e a r o un d a h o r i z o n t a l a x i s
t h e r e a d i n g on t h e a u x i l i a r y d e t e c t o r c an be m a i n ta i n ed a t a c o n s t a n t l eve l
v i a
a
c o r r e s p o n d i n g a d j u s t m e n t
of
t h e s u p p l y v o l t a g e .
A
s ec on d p o s s i b i l i t y c o n s i s t s i n k e e p i n g t h e s u p p l y v o l t a g e o f t h e l i g h t
s o u r c e c o n s t a n t an d c o r r e c t i n g t h e m e as u re d l u m in o us i n t e n s i t y i n e ac h
d i r e c t i o n by means
o f a
c o r r e c t i o n f a c t o r .
L u m i n o u s
i n t e n s i t y
of
l i g h t source
K C o r r e c t i o n f a c to r
I,,,, i 4 e a s u r e d ( i n a c c u r a t e ) l u m i n o u s i n t e n s i t y
T h e c o r r e c t i o n F a c t o r K
f o l l o w s
f r o m t h e m e a su r ed r e a d i n g s o n t h e a u x i l i a r y
d e t e c t o r as
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E o R e a d i n g on t h e a u x i l i a r y d e t e c t o r f o r t h e l i g h t s o u r c e i n t h e p r e -
Eo R e a d i n g on t h e a u x i l i a r y d e t e c t o r
f o r
t h e l i g h t
source
i n t h e
s c r i b e d b ur n i ng p o s i t i o n ( a f t e r b ur n- in )
p o s i 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 8 .
6. GONIOPHOTOMETER WITH
MOVING
PHOTOMETER HEAD [ 2,4,18]
6 . 1
P R I N C I P L E
I n these g o n i o p h o t o m e t e r s t h e l i g h t s o u r c e i s t u r n e d a r o u n d
a
v e r t i c a l
a x i s a nd t h e p h o to m e t e r n e a d moves a ro un d t h e l i g h t s o u r c e i n a v e r t i c a l
p l a n e
I n s t e a d o f a mo vi ng p h o t o m e t e r h e a d on e c a n a l s o use a number o f f i x e d pho-
t o m e t e r h e a d s t h a t
are
p o s i t i o n e d
i n a ver t i ca l
p l a n e , c o r r e s p o n d i n g
t o the
movement
o f a
p h ot om e t er h ea d . The p o s s i b i l i t y a l s o
e x i s t s
t o r e p l a c e t h e
p r o c e s s o f t u r n i n g t h e l am p b y a n a r r a ng e m e n t o f p h o t om e t e r h e a d s i n
a
num ber o f v e r t i c a l p l a n e s .
N o te :
T he u s e o f f i x e d p ho t o m e te r h e a d s i n o ne or more
ve r t i c a l
p l a n e s
re-
q u i r e s
a
number
o f
p ho to m et er h e ad s c o r r e s p o n d in g t o t h e d e s i r e d a n g u l a r
s t e p s . A l l p h ot om e t er h e a d s ha ve t o b e c a l i b r a t e d s e p a r a t e l y , w hic h i s
i n p r a c t i c e q u i t e
a
d i s a d v a n t a g e .
I n
t u r n i t is p o s s i b l e
t o
u s e a sim-
p l e r m e c ha n i ca l c o n s t r u c t i o n a nd t h e m e a s ur in g
time
i s s i g n i f i c a n t l y re-
d u c e d .
6.2
APPLICATION
S i n c e t h e l i g h t s o u r c e i s t u r n e d o n l y ab ou t t h e v e r t i c a l a x i s i n these
p h o t o m e t e r s a n d
can
t h e r e f o r e b e me as ure d i n i t s n o r m a l b u r n i n g , p o s i t i o n i t
i s
p o s s i b l e t o m e as ur e a l l k i n d s
o f
l am p s a nd l u m i n a i r e s c o n t a i n i n g
t h e m .
The p r e r e q u i s i t e f o r a n a c c u r a t e m ea su re me nt i s a
s u f f i c i e n t l y
l a r g e
d i s t a n c e b etw ee n t h e l i g h t s o u r c e and t h e p ho to rn et er h ea d; t h i s d i s t a n c e
d e p e n d s
o f
c o u r s e
on
t h e p h o t o m e t e r h e a d u s e d . I f a p h o t om e t e r h e a d f o r
i l l u m i n a n c e m e a s u r e m e n t s is u s e d i t is g e n e r a l l y n e c e s s a r y t o use a
room
o f
r e l a t i v e l y g r e a t d e p t h an d h e i g h t .
6 . 3
CONSTRUCTION
PRINCIPLES
F o r
g o n i o p h o t o m e t e r s w i t h
a
m o v in g p h o to rn e te r head t h e r e a r e b a s i c a l l y
t h r e e
t y p e s
2 1
pyright International Commission on Illumination
ovided by IHS under license with CIE
Not for Resalereproduction or networking permitted without license from IHS
--```,,-`-`,,`,,`,`,,`---
-
8/9/2019 CIE 70-1987
32/54
~~
~~~~~ ~~
CIE 70 87
9006345 0003049 387
T j p e 1 :
The l i g h t
s o u r c e
is
t t r r n e d
at
t he
p o i n t of
i n t e r s e c t i o n
o f t h e
h o r i z o n t a l and v e r t i c a l
a x e s
a r o u n d a v e r t i c a l a x i s . The phota-
meter head
1s t u r n e d a r o u n d
a h o r i z o n t a l
a x i s
( F i g 4f t er na-
t i v e l y t h e p h o t o m e t e r
head
c a n
be
moved on
a
c i r c l e i n t h e
v e r t i c a l p la n e
a r o u n d t h e
l i g h t s o u r ce w i t h o u t a n y m e c h a n i c a l
c o u p l i n g
wi t h t he
l i g h t sour ce
( F i g .
7 5 ) .
14).
PHOTOMETER
HEAD
6
i
Fig. 14: G o n i o p h o t o m e t e r w i t h m o v i n g p h o t o m e t e r
head,
type 1.
T h e p h o t o -
meter h e a d is t u r n e d a r o u n d a h o r i z o n t a l ax i s .
.-.-.-.-.-.--
IGHT SOURCE
/
l
PHOTOME; ER HEAD
A
T i o . 15
G o n i o p h o t o m e te r w i t h m o vi ng p h o t o m e t e r h e a d , t y p e 1. The
p h o t o -
meter head moves on a
c i r c l e
a r o u n d t h e m e a s u r i n g o b j e c t w i t h o u t
d i r e c t m e c ha n ic a l c o u p l i n g .
22
pyright International Commission on Illumination
ovided by IHS under license with CIENot for Resalereproduction or networking permitted without li cense from IHS
- - ` ` ` , , - ` - ` , ,
` , ,
` ,
` , ,
` - - -
-
8/9/2019 CIE 70-1987
33/54
C I E 7 0 87 e O O b L 4 5 0003050 O T 7
Type
2 :
L i g h t
source
a n d p h o t o m e t e r h e a d a r e
at
t h e o p p o s i t e e n d s o f a
beam, which
is t u r n e d
a r o u n d
a
h o r i z o n t a l
a x i s
t h r o u g h t h e
centre
o f t h e
beam
f’201.
T h e p h o t o m e t e r h e a d i s r i g i d l y f i x e d
t o
t h e
beam, w h i l e t h e h o r i z o n t a l s p i n d l e s u p p o r t i n g t h e l u m i -
n a i r e e n s u r e s t h a t t h e l u m i n a i r e h a n gs down l i k e
a
plumb bob
a s
t h e
b e a m r o t a t e s .
T h e
l i g h t s o u r c e
is
t u r n e d
i n
t h e p r e -
s c r i b e d b u r ni n g p o s i t i o n a r ou n d a v e r t i c a l a x i s and t h e p ho to -
metric
c e n t r e o f t h e l i g h t
source is
t u r n e d
around
a h o r i z o n -
t a l a x i s i n a C - p l a n e ( F i g .
1 6 ) . I t
must
be
m e n t i o n e d
t h a t
many t y p e s o f l a m p s
have a
t e m p er a tu r e -d e p e n de n t l i g h t o ut -
p u t . T h e r e f o r e
a i r
v e l o c i t y b e c a u s e o f la mp mo vem en t
must
b e
k e p t
l o w . R o t a t i n g t h e l a m ps c a n a l s o g i v e
r i s e
t o c h an g e s
b e c a u se o f c e n t r i f u g a l movem ent o f ,
f o r instance,
l i q u i d
metal.
T h e r e q u i r e d r o o m d e p t h
i s
o n ly h a l f t h a t o f t y p e
1.
The
use
o f
t h i s t y p e
is
o n l y m e a n i n g f u l
i n
c o n j u n c t i o n
w i t h a
p h o t o m e