BS ISO 80000-7-2008

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BS ISO

80000-7:2008

ICS 01.060

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BRITISH STANDARD

Quantities and units

Part 7: Light

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This British Standard was

published under the

authority of the Standards

Policy and Strategy

Committee on 31 January

200

© BSI 2008

ISBN 978 0 580 54867 3

Amendments/corrigenda issued since publication

Date Comments

BS ISO 80000-7:2008

National foreword

This British Standard is the UK implementation of ISO 80000-7:2008. It

supersedes BS ISO 31-6:1992 which is withdrawn.

The UK participation in its preparation was entrusted to Technical

Committee SS/7, General metrology, quantities, units and symbols.

A list of organizations represented on this committee can be obtained on

request to its secretary.

This publication does not purport to include all the necessary provisions

of a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity

from legal obligations.

9

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Contents Page

Foreword........................................................................................................................................................ iv

Introduction ................................................................................................................................................... vi

1 Scope .................................................................................................................................................... 1

2 Normative references .......................................................................................................................... 1

3 Names, symbols and definitions ............................................................................................... ......... 1

Bibliography ................................................................................................................................................ 44

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ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies(ISO member bodies). The work of preparing International Standards is normally carried out through ISOtechnical committees. Each member body interested in a subject for which a technical committee has beenestablished has the right to be represented on that committee. International organizations, governmental andnon-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the InternationalElectrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standardsadopted by the technical committees are circulated to the member bodies for voting. Publication as anInternational Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patentrights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 80000-7 was prepared by Technical Committee ISO/TC 12, Quantities, units, symbols, conversion factors in cooperation with IEC/TC 25, Quantities and units, and their letter symbols .

This first edition of ISO 80000-7 cancels and replaces the third edition of ISO 31-6:1992. It also incorporates theAmendment ISO 31-6:1992/Amd.1:1998. The major technical changes from the previous standard are thefollowing:

— the presentation of numerical statements has been changed;— 0.5.3 Photopic quantities , 0.5.4 Scotopic quantities and 0.5.5 Values have been added;

— the normative references have been changed;

— new items have been added and denoted by dash (see 0.1);

— the order and the definitions of luminous terms have been changed to bring the presentation more in linewith the International Electrotechnical Vocabulary.

ISO 80000 consists of the following parts, under the general title Quantities and units :

— Part 1: General

— Part 2: Mathematical signs and symbols to be used in the natural sciences and technology

— Part 3: Space and time

— Part 4: Mechanics

— Part 5: Thermodynamics

— Part 7: Light

— Part 8: Acoustics

— Part 9: Physical chemistry and molecular physics

— Part 10: Atomic and nuclear physics

— Part 11: Characteristic numbers

— Part 12: Solid state physics

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IEC 80000 consists of the following parts, under the general title Quantities and units :

— Part 6: Electromagnetism

— Part 13: Information science and technology

— Part 14: Telebiometrics related to human physiology

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Introduction

0.1 Arrangements of the tables

The tables of quantities and units in this International Standard are arranged so that the quantities arepresented on the left-hand pages and the units on the corresponding right-hand pages.

All units between two full lines on the right-hand pages belong to the quantities between the corresponding fulllines on the left-hand pages.

Where the numbering of an item has been changed in the revision of a part of ISO 31, the number in the

preceding edition is shown in parenthesis on the left-hand page under the new number for the quantity; a dashis used to indicate that the item in question did not appear in the preceding edition.

0.2 Tables of quantities

The names in English and in French of the most important quantities within the field of this InternationalStandard are given together with their symbols and, in most cases, their definitions. These names and symbolsare recommendations. The definitions are given for identification of the quantities in the International System ofQuantities (ISQ), listed on the left hand pages of the table; they are not intended to be complete.

The scalar, vector or tensor character of quantities is pointed out, especially when this is needed for thedefinitions.

In most cases only one name and only one symbol for the quantity are given; where two or more names or twoor more symbols are given for one quantity and no special distinction is made, they are on an equal footing.When two types of italic letters exist (for example as with and ; and ; a and ; g and ) only one of theseis given. This does not mean that the other is not equally acceptable. It is recommended that such variantsshould not be given different meanings. A symbol within parenthesis implies that it is a reserve symbol, to beused when, in a particular context, the main symbol is in use with a different meaning.

In this English edition, the quantity names in French are printed in an italic font, and are preceded by fr . Thegender of the French name is indicated by (m) for masculine and (f) for feminine, immediately after the noun inthe French name.

0.3 Tables of units

0.3.1 General

The names of units for the corresponding quantities are given together with the international symbols and thedefinitions. These unit names are language-dependent, but the symbols are international and the same in alllanguages. For further information, see the SI Brochure (8th edition 2006) from BIPM and ISO 80000-11).

The units are arranged in the following way.

a) The coherent SI units are given first. The SI units have been adopted by the General Conference on

Weights and Measures (Conférence Générale des Poids et Mesures, CGPM). The use of coherent SI units,

1) To be published.

ϑ θ ϕ φ a g

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0.5.4 Scotopic quantities

For scotopic vision (provided by the rods and used for vision at night), corresponding quantities from item 7-28to item 7-48 are defined in the same manner as the photopic ones, using symbols with a prime.

For item 7-28, spectral luminous efficiency, the remarks would read:Standard values of luminous efficiency function for scotopic vision were originally adopted by CIE in1951. They were later adopted by the CIPM [see BIPM Monograph: Principles Governing Photometry (1983)].

For item 7-29, maximum spectral luminous efficacy (for scotopic vision), the definition would read:

“for scotopic vision, .”

0.5.5 Values

The fundamental physical constants given in ISO 80000-7 series are quoted in the consistent values of thefundamental physical constants published in “2006 CODATA recommended values”. See also CODATA websiteredirecting to: http://physics.nist.gov/cuu/Constants/index.html.

V (λ)

K m =683

V (555,016 nm)lm/W ≈ 1 700 lm/W

http://physics.nist.gov/cuu/Constants/index.html



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UNITS LIGHT

Item No. Name Symbol Definition Conversion factors and

remarks

7-1.a hertz Hz 1 Hz 1 s–1

7-2.a metre to powerminus one

m–1 The unit for wavenumbercommonly used inspectroscopy is centimetre topower minus one, cm–1, ratherthan metre to power minus one,m–1.

7-3.a metre m ångström (Å); 1 Å

(continued)

:=

:= 10−10 m

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LIGHT QUANTITIES

Item No. Name Symbol Definition Remarks

7-4.1(6-6 )

speed of light invacuum,speed of electro-magnetic wavesin vacuum

fr vitesse (f) de la lumière dans le vide,

vitesse (f) des ondes électro- magnétiques dans le vide

speed of electromagneticwaves in vacuum

The speed of light in vacuum is afundamental constant used fordefinition of metre. SeeISO 80000-3:2006, item 3-1.a andIEC 80000-6:2008, item 6-35.2.

In relativity, the terms subluminal,luminal and superluminal speedare sometimes used for speedless than, equal to, or greater thanthe speed of light in vacuum.

7-4.2 speed of lightfr vitesse (f) de la

lumière

in a medium, the phase speed(ISO 80000-3:2006, item 3-8.2)of electromagnetic radiation in agiven direction and of aspecified frequency

7-5(6-44 )

refractive indexfr indice (m) de

réfraction where is the speed of lightin vacuum (item 7-4.1) and

is the phase speed(ISO 80000-3:2006, item 3-8.2)in a given direction ofelectromagnetic radiation of aspecified frequency in amedium

In a medium, depends upon thefrequency of light used; thus

.

For a medium with absorption,complex refractive index k k0 may be defined where k0 is thewave vector in vacuum and k isthe complex wave vector in amedium. Then,

whereis the linear absorption

coefficient (item 7-25.2) and i isthe imaginary unit.

For an anisotropic medium, is atensor.

7-6(6-7 )

radiant energyfr énergie (f)

rayonnante

, ,( , )

energy (ISO 80000-5:2007,item 5-20.1) emitted,transferred or received asradiation

Visible radiant energy is calledluminous energy (item 7-34).Photonic energy may beexpressed by photon numbers(item 7-49).

c0

c0 := 299 792 458 m · s−1

c

n n = c0 / c

c0

c

cν

n = n(ν )

= n

n = n + ik = n + iα /4πν α

n

Q W U Qe

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remarks

7-4.a metre per second m·s–1

7-5.a one 1 See the Introduction, 0.3.2.

7-6.a joule J

(continued)

1 J := 1 kg · m2 · s−2

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remarks

7-10.a second to thepower minus one

s–1

7-11.a second kilogram tothe power minus

one

s·kg–1 For the coefficients usingspectral energy density in

terms of frequency , the SI unitis m·kg–1.

7-12.a second kilogram tothe power minusone

s·kg–1 For the coefficients usingspectral energy density interms of frequency , the SI unitis m·kg–1.

(continued)

Bν , jkρν (ν )

ν

Bν , kjρν (ν )

ν

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7-13.a watt W 1 W = 1 J·s–1

This unit is identical to the unitfor mechanical power(ISO 80000-4:2006, item4-26.a).

7-14.a watt per steradian W·sr–1 For the steradian, see theIntroduction, 0.3.2.

(continued)

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7-15.a watt per steradianmetre squared

W·sr–1·m–2

(continued)

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7-16.a watt per metresquared

W·m–2

7-17.a joule per metresquared

J·m–2


W·m–2

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7-19(6-16 )

irradiancefr éclairement (m)

énergétique

, ( ) at a point on a surface,

where is the radiant flux(item 7-13) incident on anelement of the surface with area

(ISO 80000-3:2006, item3-6)

where is spectralirradiance.

See the Introduction, 0.5.1, andthe Remarks in item 7-13.

Visible irradiance is calledilluminance (item 7-36). Photonicirradiance may be expressed byphoton numbers (see item 7-54).

7-20(6-17 ) radiant exposurefr exposition (f)

énergétique

, ( )

where is the irradiance (item7-19) acting during the timeinterval with duration(ISO 80000-3:2006, item 3-7)

Visible radiant exposure is calledluminous exposure (item 7-41).Photonic radiant exposure may beexpressed by photon numbers(see item 7-55).

7-21.1(6-21.1)

emissivity,emittance

fr émissivité (f) where is the radiant exitance(item 7-18) of a thermal radiatorand is the radiant exitance

of a blackbody at the sametemperature(ISO 80000-5:2007, item 5-1)

7-21.2(6-21.2 )

spectral emissivity,emissivity at a

specifiedwavelength

fr émissivité (f)spectrale

where is the spectralradiant exitance (item 7-18) of athermal radiator andis the spectral radiant exitanceof a blackbody at the sametemperature

The spectral emissivity is afunction of wavelength (item7-3.2); this is usually indicated bythe symbol . For ,see item 7-18 and Remarks initem 7-13.

E E e

E =dΦ

dAdΦ

dA

E =

∞ 0

E λ(λ) dλ

E λ(λ)

H H e H =∆t 0

E dt

E

∆t

ε ε = M / M b

M

M b

ε (λ) ε (λ) = M λ(λ)/ M b,λ(λ)

M λ (λ)

M b,λ (λ)ε (λ) M λ (λ)

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W·m–2

7-20.a joule per metresquared J·m–2


(continued)

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7-22.1(6-40.1)

absorptancefr facteur (m)

d'absorption,absorptance (f)

,

where is the absorbedradiant flux (item 7-13) or theabsorbed luminous flux (item7-32) and is the radiant flux(item 7-13) or luminous flux(item 7-32) of the incidentradiation

, .

These quantities are also definedspectrally, in which case,“spectral” is added before thesequantity names (e.g. spectralreflectance), and the symbols areexpressed as , and ,respectively. The quantities , ,are averages of the spectralquantities weighted by the spectraldistribution of the used light.

Due to the energy conservation,except when

polarized radiation is observed.

See also items 7-47.1, 7-47.2 and7-47.3

7-22.2(6-40.2 )

reflectancefr facteur (m) de

réflexion,réflectance (f)

where is the reflected radiantflux (item 7-13) or the reflected

luminous flux (item 7-32) andis the radiant flux (item7-13) or luminous flux (item7-32) of the incident radiation

7-22.3(6-40.3 )

transmittancefr facteur (m) de

transmission,transmittance (f)

,

where is the transmittedradiant flux (item 7-13) orluminous flux (item 7-32) and

is the radiant flux (item7-13) or luminous flux (item7-32) of the incident radiation

7-23.1(6-41)

transmittancedensity,

optical density,decadic

absorbancefr densité (f)

optique,absorbance (f)

,

where is the transmittance(item 7-22.3) at givenwavelength (item 7-3.2)

In spectroscopy, the name“absorbance ” is generallyused.

7-23.2(—)

napierianabsorbance

fr absorbance (f)népérienne

,

where is the transmittance

(item 7-22.3) at givenwavelength (item 7-3.2)

where is the linear absorption

coefficient (item 7-25.2) and isthe length (ISO 80000-3:2006,item 3-1.1) traversed.

α a α = Φa / Φm

Φa

Φm

α = I a / I m ρ = I r / I m, ρ = I t / I m

α(λ) ρ(λ) τ (λ)α ρ τ

α + ρ + τ =1

ρ ρ = Φr / Φm

Φr

Φm

τ T ρ = Φt / Φm

Φt

Φm

A10 D A10(λ) = −lg (τ (λ))

τ

λ

A10

Ae B Ae(λ) = −ln (τ (λ))

τ

λ

Ae(λ) = lαλ(λ)

α

l

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7-24.1(6-40.4 )

radiance factorfr facteur (m) de

luminance énergétique

, ( )

where is the radiance (item7-15) of a surface element in agiven direction and is theradiance (item 7-15) of theperfect reflecting or transmittingdiffuser identically irradiatedand viewed

Reflectance factor is equivalent toradiance factor or luminance factor(item 7-48) when the cone angle isinfinitely small, and is equivalent toreflectance when the cone angle is

sr.

These quantities are also definedspectrally and called spectralradiance factor and spectralreflectance factor .

The ideal isotropic (Lambertian)diffuser with reflectance ortransmittance equal to 1 is called aperfect diffuser.

7-24.2(—)

reflectance factorfr facteur (m) de

réflectance where is the radiant flux(item 7-13) or luminous flux(item 7-32) reflected in thedirections delimited by a givencone and is the flux reflectedin the same directions by anidentically irradiated diffuser ofreflectance (item 7-22.2) equalto 1

7-25.1(6-42.1)

linear attenuationcoefficient,

linear extinctioncoefficient

fr coefficient (m)d'atténuation

linéique

,

where is the relative

decrease in the spectral radiant

flux (item 7-13) of acollimated beam of electro-magnetic radiationcorresponding to thewavelength (item 7-3.2)during traversal of aninfinitesimal layer of a mediumand is the length(ISO 80000-3:2006, item 3-1.1)traversed

Spectral attenuation coefficient isthe corresponding spectralquantity. Similarly, luminous andphoton quantities can be defined.

7-25.2(6-42.2 )

linear absorptioncoefficient

fr coefficient (m)d'absorption linéique

,

where is the relative

decrease, caused byabsorption, in the spectralradiant flux (item 7-13) of acollimated beam of electro-magnetic radiation corresp-onding to the wavelength(item 7-3.2) during traversal ofan infinitesimal layer of amedium and is the length

(ISO 80000-3:2006, item 3-1.1)traversed

Linear absorption coefficient isthat part of the linear attenuationcoefficient that is due toabsorption. Scattering might alsocontribute. See Remarks in item7-25.1.

β β e β = Ln / Ld

Ln

Ld

2π

β (λ)R(λ)R R = Φn / Φd

Φn

Φd

µ µlµ(λ) =

1

Φλ(λ)

dΦλ(λ)

dl

dΦ

Φ

Φ

λ

dl

α aα(λ) =

1

Φλ(λ)

dΦλ(λ)

dldΦ

Φ

Φ

λ

dl

α = −ln(T )/ l = Ae / l

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remarks


7-25.a metre to the powerminus one

m–1

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7-26.1(—)

mass attenuationcoefficient

fr coefficient (m)d'atténuation massique

where is the linearattenuation coefficient (item7-25.1) and is the massdensity (ISO 80000-4:2006,item 4-2) of the medium

See Remarks in item 7-25.1.

7-26.2(—)

mass absorptioncoefficient

fr coefficient (m)d'absorption massique

where is the linear absorptioncoefficient (item 7-25.2) andis the mass density(ISO 80000-4:2006, item 4-2) of

the medium


7-27(6-43 )

molar absorptioncoefficient

fr coefficient (m)d'absorption molaire

where is the linear absorptioncoefficient (item 7-25.2) andis the molar volume(ISO 80000-9:—, item 9-6)


where is the amount-of-substance concentration(ISO 80000-9:—, item 9-13).

7-28(6-37.2 )

spectral luminousefficiency

fr efficacité (f)lumineuse relative spectrale

ratio of the spectral radiant flux(item 7-13) at

wavelength (item 7-3.2) tospectral radiant flux (item7-13) at wavelength (item7-3.2) such that both radiationsproduce equal luminoussensations under specifiedphotometric conditions andis chosen so that the maximumvalue of this ratio is equal to 1

Standard values of spectralluminous efficiency functionfor photopic vision were originallyadopted by the CIE in 1924. Thesevalues were adopted by the CIPM(see Reference [3]).

is used for quantitiesdescribing photopic vision.

For scotopic vision, see 0.5.4.

7-29(6-36.3 )

maximum spectralluminous efficacy

fr efficacité (f)lumineuse

spectrale maximale where is the spectral

luminous efficiency (item 7-28)

The value is defined formonochromatic radiation atfrequency( in standard air) in the

SI definition of the candela. is the maximum value of

.


µm µm = µ / ρ

µ

ρ

am am = a / ρ

aρ

κ κ = aV m

aV m

κ = ac c

V (λ)Φλ(λm)

λmΦλ

(λ)λ

λm

V (λ)

V (λ)

K mK m =

683

V (555,016 nm)lm/W

≈ 683 lm/W

V (λ)

683 lm/W

540 × 1012 Hz555,016 nm

K mK (λ)

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remarks

7-26.a metre squared perkilogram

m2·kg–1

7-27.a metre squared permole

m2·mol–1


7-29.a lumen per watt lm·W–1

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7-30(6-37.1)

luminous efficiencyfr efficacité (f)

lumineuse relative

where is the spectralradiant flux (item 7-13), isthe spectral luminous efficiency(item 7-28) and is thewavelength (item 7-3.2)

where is the luminous efficacyof radiation (item 7-33.1) andis the maximum spectral luminousefficacy (item 7-29).


7-31

(6-36.2 )

spectral luminous

efficacyfr efficacité (f)

lumineuse spectrale

where is the maximumspectral luminous efficacy (item7-29), is the spectralluminous efficiency (item 7-28)and is the wavelength (item7-3.2)


7-32(6-30 )

luminous fluxfr flux (m)

lumineux

, ( )

where is the maximumspectral luminous efficacy (item

7-29), is the spectralradiant flux (item 7-13, Remarks7-13), is the spectralluminous efficiency (item 7-28)and is the wavelength (item7-3.2)

Luminous flux evaluates theradiation by its visual responseusing the standard spectralluminous efficiency. See theIntroduction, 0.5.1.

For the analogous radiant quantity,see item 7-13. For the analogousphoton quantity, see item 7-50.


V

V =

∞ 0

V (λ)Φλ(λ) dλ∞ 0

Φλ(λ) dλ

Φλ(λ)V (λ)

λ

V = K / K m

K K m

K (λ) K (λ) = K m V (λ)

K m

V (λ)

λ

Φv ΦΦv = K m

∞ 0

Φλ(λ) V (λ) dλ

K m

Φλ(λ)

V (λ)

λ

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7-33.1(6-36.1)

luminous efficacyof radiation

fr efficacité (f)lumineuse d'un rayonnement

where is the luminous flux(item 7-32) and is thecorresponding radiant flux (item7-13)

For , see item 7-31.

7-33.2(—)

luminous efficacyof a source

fr efficacité (f)lumineuse d'une source

, ( )

where is the luminous flux(item 7-32) and is thecorresponding electric active

power (IEC 80000-6:2008, item6-56) consumed by the source

7-34(6-31)

luminous energy,quantity of lightfr quantité (f) de

lumière

, ( )

where is the luminous flux(item 7-32) occurring during thetime interval with duration(ISO 80000-3:2006, item 3-7)

For , see item 7-31,for , see item 7-6.

See the Introduction, 0.5.1.


For the analogous radiant quantity,see item 7-6. For the analogous

photon quantity, see item 7-49.

K K = Φv

ΦΦv

Φ

K = ∞

0 K (λ) Φλ(λ) dλ ∞

0 Φλ(λ) dλ

K (λ)

ηv ηηv =

Φv

P Φv

P

Qv QQ =

∆t 0

Φv dt

Φv

∆t

Qv = ∞

0 Qλ(λ)K (λ) dλ

K (λ)Qλ(λ)

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7-33.a lumen per watt lm·W–1

7-34.a lumen second lm·s

7-34.b lumen hour lm·h

(continued)

1 lm · h = 3 600 lm · s

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7-35(6-29 )

luminous intensityfr intensité (f)

lumineuse

, ( ) Luminous intensity is one of thebase quantities in theInternational System ofQuantities, ISQ, on which theInternational System of Units,SI, is based.

Luminous intensity is measured bya photometer.

In a given direction from a source,

where is the

luminous flux (item 7-32) leavingthe source in an elementary conecontaining the given direction withthe solid angle .

See item 7-31 for .

See the Introduction, 0.5.1.For scotopic vision, see 0.5.4.


7-36(6-34 )

illuminancefr éclairement (m)

lumineux,éclairement (m)

, ( ) at a point on a surface,

where is the luminous flux(item 7-32) incident on an

element of the surface with area(ISO 80000-3:2006, item

3-3)

See item 7-31 for .




7-37(6-32 )

luminancefr luminance (f)

, ( ) at a point on a surface and in agiven direction,

where is the luminousintensity (item 7-35) of anelement of the surface with the

area (ISO 80000-3:2006,item 3-3) of the orthogonalprojection of this element on aplane perpendicular to thegiven direction

See item 7-31 for .



For the analogous radiant quantity,

see item 7-15. For the analogousphoton quantity, see item 7-52.

I v I

I v =dΦv

dΩ dΦv

dΩ

I v = ∞

0 I λ(λ)K (λ) dλ

K (λ)

E v E

E v =dΦ

dAdΦ

dA

E v = ∞

0 E λ(λ)K (λ) dλ

K (λ)

Lv L

Lv =dI vdAdI v

dA

Lv = ∞

0 Lv,λ(λ)K (λ) dλ

K (λ)

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7-35.a candela cd The candela is the luminousintensity, in a given direction, ofa source that emitsmonochromatic radiation offrequency andthat has a radiant intensity inthat direction of 1/683 W/sr

7-36.a lux lx

7-37.a candela per squaremetre

cd·m–2

(continued)

540 × 1012 Hz

1 lx := 1 lm · m−2

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7-38.a lux lx

7-39.a lux second lx·s

7-39.b lux hour lx·h

7-40.a lumen per squaremetre

lm·m–2

7-41.a lux second lx·s

7-41.b lux hour lx·h

(continued)

1 lx · h = 3 600 lx · s

1 lx · h = 3 600 lx · s

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7-42(—)

colour stimulusfunction,

relative colourstimulus function

fr courbe (f) d'un stimulus de couleur ,

courbe (f) relative d’un stimulus de couleur

where is the spectraldistribution of a radiometricquantity , such asradiance (item 7-15) or radiantflux (item 7-13), as a function ofwavelength (item 7-3.2), and

is a fixed reference value

7-43(—)

tristimulus valuesfr composantes (f)

trichromatiques

, , ;, ,

amounts of the three referencecolour stimuli, in a given

trichromatic system, required tomatch the colour of the stimulusconsidered. For a given colourstimulus described by thecolour stimulus functionof a radiometric quantity,

where , , are theCIE colour matching functions(item 7-44), and analogousexpressions are for , ,

.

, , are in the 1931 CIEcolorimetric system.

, , are in the 1964 CIEcolorimetric system.

For sources, may be chosen aswhere is maximum

luminous spectral efficacy (item7-29).

For object colours, is givenby one of the three products

where is the relativespectral distribution of a quantitycharacterizing the sourceilluminating the object, isluminous reflectance (item7-47.2), is luminoustransmittance (item 7-47.3),is luminous factor (item 7-48), and

is chosen to be

ϕλ(λ) ϕλ

(λ

) = X λ

(λ

)/ R

X λ(λ)

X (λ)

R

X Y Z X 10 Y 10

Z 10

ϕλ(λ)

X = k

∞

0

ϕλ(λ)x(λ) dλ

Y = k

∞

0

ϕλ(λ)y(λ) dλ

Z = k

∞ 0

ϕλ(λ)z(λ) dλ

x(λ) y(λ) z(λ)

X 10 Y 10

Z 10

X Y Z

X 10 Y 10 Z 10

kk = K m K m

ϕλ(λ)

ϕλ(λ) = S λ(λ) ·

ρ(λ)τ (λ)

β (λ)S λ(λ)

ρ(λ)

τ (λ)β (λ)

k

k = 100/∞

0

S λ(λ)y(λ) dλ

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remarks

7-42.a one 1

7-43.a See Remarks For more information, see e.g.Reference [3].

(continued)

[X ] = [Y ] = [Z ] = [k] · m

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7-44(6-38 )

CIE colour-matchingfunctions

fr fonctions (f)colorimétrique CIE

, ,;

,,

tristimulus values ofmonochromatic stimuli of equalradiant power

Values of , , aredefined in the 1931 CIEcolorimetric system (observer) — applicable to fields ofobservation of angular openingfrom to .

The “CIE 1931 colour space” wascreated by the InternationalCommission on Illumination (CIE)in 1931.

Values of , ,are defined in the 1964 CIEcolorimetric system (observer) — applicable to fields ofobservation with angles greaterthan .

7-45(6-39 )

chromaticitycoordinates

fr coordonnées (f)trichromatiques

, , ;

, ,

ratio of each of a set of threetristimulus values to their sum,thus

,,

and similar expressions apply to

, ,

Values of , , are in the1931 CIE colorimetric system (observer).

Values of , , are in the1964 CIE colorimetric system (observer).

Since , twovariables , are sufficient toexpress chromaticity.

7-46(—)

colour temperaturefr température (f)

de couleur

temperature of a blackbodywhose radiation has the samechromaticity coordinates (item7-45)

x(λ) y(λ)z(λ)

x10(λ)y10(λ)z10(λ)

x(λ) y(λ) z(λ)

2

1 4

x10(λ) y10(λ) z10(λ)

10

4

x y z

x10 y10z10 x = X /(X + Y + Z )

y = Y /(X + Y + Z )z = Z /(X + Y + Z )

x10 y10 z10

x y z2

x10 y10 z1010

x + y + z = 1x y

T c

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7-46.a kelvin K

(continued)

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(continued)

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remarks

7-50.a second to thepower minus one

s–1

7-51.a second to thepower minus oneper steradian

s–1·sr–1

7-52.a second to the

power minus oneper steradianmetre squared

s–1·sr –1·m–2

7-53.a second to the

power minus oneper metresquared

s–1·m–2

(continued)

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7-54(6-27 )

photon irradiancefr éclairement (m)

photonique

, at a point on a surface, thephoton flux (item 7-50)incident on an element of thesurface, divided by the area

(ISO 80000-3:2006, item3-3) of that element, thus

For the analogous radiant quantity, seeitem 7-19. For the analogous visiblequantity, see item 7-36.

7-55(6-28 )

photon exposurefr exposition (f)

photonique

, time integral of photonirradiance (item 7-54)during the duration(ISO 80000-3:2006, item

3-7), thus

For the analogous radiant quantity, seeitem 7-20. For the analogous visiblequantity, see item 7-41.

7-56(6-18 )

Stefan-Boltzmannconstant

fr constante (f) de Stefan- Boltzmann

constant in the expressionfor the radiant exitance (item7-18) of a blackbody atthermodynamic temperature

(ISO 80000-5:2007, item5-1), thus

See CODATA 2006 [4].

Further,

where is the Boltzmann constant(ISO 80000-9:—, item 9-37), is thePlanck constant (ISO 80000-10:—, item10-6.1) and is the speed of light invacuum (item 7-4.1).

7-57(6-19 )

first radiationconstant

fr première constante (f) de rayonnement

constants and in theexpression for the spectralradiant exitance (item 7-18)of a blackbody at thethermodynamic temperature

(ISO 80000-5:2007, item5-1), thus

See CODATA 2006 [4].

Further, , and

where is the Boltzmann constant(ISO 80000-9:—, item 9-37), is thePlanck constant (ISO 80000-10:—, item10-6.1) and is the speed of light invacuum (item 7-4.1).

The name “first radiation constant” hasalso been used for the factorsand in the correspondingexpressions for and (seeRemarks in items 7-13 and 7-15)

7-58(6-20 )

second radiationconstant

fr seconde constante (f) derayonnement

E p E dΦp

dA

E p = dΦp /dA

H p H E p

∆t

H p =∆t 0

E p dt

σ σ

T

M = σT 4

σ = 5,670 400(40) × 10−8

W · m−2 · K−4

σ =2π5k4

15h3c20

k

hc0

c1 c1 c2

T

M λ(λ) = c1f (λ, T ) =

c1λ−5

exp(c2λ−1 T −1) − 1

c1 = 3,741 771 18(19)× 10−16 W · m2

c2 = 1,468 775 2(25)× 10−2 m · K

c1 = 2πhc20 c2 = hc0 / k

kh

c0

8πhc0hc2

0wλ Lλ(λ)

c2

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remarks

7-54.a second to thepower minus oneper metresquared

s–1·m–2

7-55.a metre to the powerminus two

m–2

7-56.a watt per metresquared kelvin tothe power four

W·m–2·K–4

7-57.a watt metresquared

W·m2

7-58.a metre kelvin m·K

(continued)

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7-59.1(6-45.1)

object distancefr distance (f) de

l'objet

for a centred optical system,distance (ISO 80000-3:2006,item 3-1.9) from a given objectto the closest surface of thecentred optical system

Distances are taken positive in thedirection of the light flow andnegative in the opposite distance.Then, for a thin lens,

and

When , the absolutevalue is often called focaldistance.

7-59.2(6-45.2 )

image distancefr distance (f) de

l'image

for a centred optical system,distance (ISO 80000-3:2006,item 3-1.9) from an image of thegiven object to the closestsurface of the centred opticalsystem

7-59.3(— )

object focaldistance

fr distance (f) focale de l'objet

for a centred optical system,distance (ISO 80000-3:2006,item 3-1.9) from the focal pointat the object side to the closestsurface of the centred opticalsystem

7-59.4(— )

image focaldistance

fr distance (f) focale de l'image

for a centred optical system,distance (ISO 80000-3:2006,item 3-1.9) from the focal pointat the image side to the closestsurface of the centred optical

system

7-60(6-46 )

lens powerfr vergence (f)

algebraic quantitycharacterizing the focusingproperties of an optical system,thus where is theobject focal distance (item7-59.3)

7-61(—)

degree of linearpolarization

fr degré (m) de

polarisation rectiligne

where is the radiant intensity(item 7-14) or the luminous

intensity (item 7-35) observedthrough an ideal polarizer whenthe polarizer is set so that theintensity transmitted is maximal,and is the intensity when thepolarizer is set perpendicular tothat direction.

The degree of circular polarizationcan be observed behind aplate.

p

f = −f 1

p −

1

p =

1

f

f = −f |f |

p

f

f

ϕ

ϕ = 1/ f f

P P = (I 0 − I 1)/(I 0 + I 1)

I 0

I 1

λ /4

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remarks

7-59.a metre m

7-60.a metre to the powerminus one

m–1 In optics, diopter D is oftenused:

.


(concluded)

1 D := 1 m−1

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BS ISO

80000-7:2008

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BS ISO 80000-7-2008