Mise en pratique for the definition of the candela and associated derived units for photometric and radiometric quantities in the International System of Units (SI)

Zwinkels, Joanne C.; Sperling, Armin; Goodman, Teresa; Acosta, Joaquín Campos; Ohno, Yoshi; Rastello, María Luisa; Stöck, M; Woolliams, Emma

doi:10.1088/0026-1394/53/3/g1

Cited by 10 publications

(5 citation statements)

References 7 publications

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“…The refractive index of air is very close to 1. At standard reference conditions of air (at a temperature of 15 °C, a pressure of 1013.25 hPa and with a content of CO 2 of 0.045%), a value of n = 1,00028 and

λ_{cd} = 555.017 nm

is given in the literature . However, as the refractive index of ambient air depends on the composition, pressure, and temperature, already a change in temperature and pressure to 25 °C and 933 hPa will lead to an increase in the wavelength to

λ_{cd} = 555.034 nm

, if the model given in literature is used .…”

Section: Photometric Realization Of the Candelamentioning

confidence: 99%

“…Since 1968 the value of

c_{2} = 1.4388 \cdot 10^{7} nm normalK

is used, yielding the black‐body temperature of

T = 2855.54 normalK

(

\approx 2856 normalK

). With the new SI, the values of the three natural constants

c, h and k

are now fixed and the resulting constant in Equation will be

c_{2} = 1, 43877688 nm normalK

. Accordingly, the corresponding temperature of a Planckian radiator which will fit to the tabulated spectral distribution of the illuminant A will change to

T = 2855.49 normalK

(

\approx 2855 normalK

).…”

Section: The Concept Of Illuminantsmentioning

confidence: 99%

“…For photometry, these quanta are photons of specific wavelength, which can be counted. In other words, the candela and the further derived units in photometry and radiometry are expressed in terms of a known number of photons with known wavelength, because of the dual aspect of electromagnetic radiation (see also the “mise en pratique” of the candela). Hence, photometric, radiometric, and specifically spectral radiant quantities might be expressed in terms of photon‐numbers and photon number‐based quantities.…”

Section: Photon‐number‐based Traceability Of Photometric and Radiometmentioning

confidence: 99%

“…Hence, photometric, radiometric, and specifically spectral radiant quantities might be expressed in terms of photon‐numbers and photon number‐based quantities. The relation between a spectral radiant quantity and the corresponding photon‐number‐based quantity is rather simple, for a given wavelength in air it is:

X_{e, λ} (λ) = \frac{h c}{λ} n_{normala} (λ) X_{p, λ} (λ)

where

X_{e, λ} false(λ false)

is the spectral radiant quantity at a given wavelength,

X_{p, λ} false(λ false)

is the corresponding photon‐number‐based quantity, h is the Planck‐constant, c is the speed of light in vacuum, and

n_{normala} false(λ false)

is the refractive index of air at the given wavelength, λ.…”

Section: Photon‐number‐based Traceability Of Photometric and Radiometmentioning

confidence: 99%

“…Combining Equation with a generalized Equation , the general form of the equation relating a given photometric quantity X v to its corresponding photon‐number‐based quantity X p is given:

0true X_{v} = K_{normalp, mes; m} \int_{λ} X_{normalp, λ} ((), λ) \frac{n_{a} ((), λ)}{λ} V_{mes; m} ((), λ) d λ

where

K_{p, mes; m} = \frac{K_{cd} h c}{V_{mes; m} false(λ_{cd} false)}

is the conversion factor from photometric to photon number‐based quantities for the spectral luminous efficiency function

V_{mes; m} false(λ false)

and λ cd as defined in Equation .…”

Section: Photon‐number‐based Traceability Of Photometric and Radiometmentioning

confidence: 99%

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The SI Unit Candela

Sperling

Kück

2019

Annalen der Physik

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The history of photometry, the measurement of light-and thus also the root of the basic unit for the luminous intensity, goes back to the seventeenth century. The theoretical foundations are provided by Johann H. Lambert in his treatise on photometry around 1760. With industrialization in the nineteenth century, there is an increasing demand for stable reference light sources for the measurement of light and for an reliable definition of the unit for light. But it is not until the middle of the twentieth century that the basic prerequisites had been created to use a common, internationally recognized unit, the Candela, as a measure of the visible light. The following article describes the basics and the boundary conditions that arise for the unit candela from the revision of the SI.

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λ_{cd} = 555.017 nm

λ_{cd} = 555.034 nm

, if the model given in literature is used .…”

Section: Photometric Realization Of the Candelamentioning

confidence: 99%

“…Since 1968 the value of

c_{2} = 1.4388 \cdot 10^{7} nm normalK

is used, yielding the black‐body temperature of

T = 2855.54 normalK

(

\approx 2856 normalK

). With the new SI, the values of the three natural constants

c, h and k

are now fixed and the resulting constant in Equation will be

c_{2} = 1, 43877688 nm normalK

. Accordingly, the corresponding temperature of a Planckian radiator which will fit to the tabulated spectral distribution of the illuminant A will change to

T = 2855.49 normalK

(

\approx 2855 normalK

).…”

Section: The Concept Of Illuminantsmentioning

confidence: 99%

Section: Photon‐number‐based Traceability Of Photometric and Radiometmentioning

confidence: 99%

X_{e, λ} (λ) = \frac{h c}{λ} n_{normala} (λ) X_{p, λ} (λ)

where

X_{e, λ} false(λ false)

is the spectral radiant quantity at a given wavelength,

X_{p, λ} false(λ false)

is the corresponding photon‐number‐based quantity, h is the Planck‐constant, c is the speed of light in vacuum, and

n_{normala} false(λ false)

is the refractive index of air at the given wavelength, λ.…”

Section: Photon‐number‐based Traceability Of Photometric and Radiometmentioning

confidence: 99%

“…Combining Equation with a generalized Equation , the general form of the equation relating a given photometric quantity X v to its corresponding photon‐number‐based quantity X p is given:

0true X_{v} = K_{normalp, mes; m} \int_{λ} X_{normalp, λ} ((), λ) \frac{n_{a} ((), λ)}{λ} V_{mes; m} ((), λ) d λ

where

K_{p, mes; m} = \frac{K_{cd} h c}{V_{mes; m} false(λ_{cd} false)}

is the conversion factor from photometric to photon number‐based quantities for the spectral luminous efficiency function

V_{mes; m} false(λ false)

and λ cd as defined in Equation .…”

Section: Photon‐number‐based Traceability Of Photometric and Radiometmentioning

confidence: 99%

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The SI Unit Candela

Sperling

Kück

2019

Annalen der Physik

Self Cite

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A Molecule‐Based Single‐Photon Source Applied in Quantum Radiometry

et al. 2019

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Single‐photon sources (SPSs) based on quantum emitters hold promise in quantum radiometry as metrology standard for photon fluxes at the low light level. Ideally this requires control over the photon flux in a wide dynamic range, sub‐Poissonian photon statistics, and narrow‐band emission spectrum. In this work, a monochromatic SPS based on an organic dye molecule is presented, whose photon flux is traceably measured to be adjustable between 144 000 and 1320 000 photons per second at a wavelength of (785.6 ± 0.1) nm, corresponding to an optical radiant flux between 36.5 and 334 fW. The high purity of the single‐photon stream is verified, with a second‐order autocorrelation function at zero time delay below 0.1 throughout the whole range. Such molecule‐based SPS is hence used for the calibration of a single‐photon avalanche detector against a low‐noise analog photodiode traceable to the primary standard for optical radiant flux (i.e., the cryogenic radiometer). Due to the narrow bandwidth of the source, corrections to the detector efficiency arising from the spectral power distribution are negligible. With this major advantage, the developed device may finally realize a low‐photon‐flux standard source for quantum radiometry.

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Radiometry, Photometry and Realization of Candela and Mole

Gupta

2020

Units of Measurement

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Mise en pratique for the definition of the candela and associated derived units for photometric and radiometric quantities in the International System of Units (SI)

Cited by 10 publications

References 7 publications

The SI Unit Candela

The SI Unit Candela

A Molecule‐Based Single‐Photon Source Applied in Quantum Radiometry

Radiometry, Photometry and Realization of Candela and Mole

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