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{{short description|Formula for the thermal radiation emitted by a perfect black body}}
In [[physics]], the '''Sakuma–Hattori equation''' is a mathematical model for predicting the amount of [[thermal radiation]], [[Radiant flux|radiometric flux]] or radiometric power emitted from a perfect [[blackbody]] or received by a thermal radiation detector.
== History ==
The Sakuma–Hattori equation was first proposed by Fumihiro Sakuma, Akira Ono and Susumu Hattori in 1982.<ref name=Sakuma1/> In 1996, a study investigated the usefulness of various forms of the Sakuma–Hattori equation. This study showed the Planckian form to provide the best fit for most applications.<ref name=Sakuma2/> This study was done for 10 different forms of the Sakuma–Hattori equation containing not more than three fitting variables. In 2008, BIPM CCT-WG5 recommended its use for radiation thermometry measurement uncertainty budgets below 960 °C.<ref name=Fischer/>
== General form ==
The Sakuma–Hattori equation gives the [[electromagnetic radiation|electromagnetic signal]] from thermal radiation based on an object's [[temperature]]. The signal can be electromagnetic [[flux]] or signal produced by a detector measuring this radiation. It has been suggested that below the silver point,{{efn | Silver point, the melting point of silver 962°C [(961.961 ± 0.017)°C<ref>
{{Cite journal
|author=J Tapping and V N Ojha
| title = Measurement of the Silver Point with a Simple, High-Precision Pyrometer
| journal = Metrologia
| volume = 26
| issue = 2
| pages = 133–139
| year = 1989
| doi = 10.1088/0026-1394/26/2/008
| bibcode = 1989Metro..26..133T
| s2cid = 250764204
}}
</ref>] used as a calibration point in some temperature scales.<ref>
{{Cite web
| title = Definition of Silver Point - 962°C, the melting point of silver
| url = http://www.eudict.com/?word=silver+point+melting&lang=engchi
| access-date = 2010-07-26}}
</ref>
It is used to calibrate IR thermometers because it is stable and easy to reproduce.}} a method using the Sakuma–Hattori equation be used.<ref name=Sakuma1>{{cite book |first1=F. |last1=Sakuma |first2=S. |last2=Hattori |chapter=Establishing a practical temperature standard by using a narrow-band radiation thermometer with a silicon detector |title=Temperature: Its Measurement and Control in Science and Industry |volume=5 |editor-first=J. F. |editor-last=Schooley |location=New York |publisher=AIP |pages=421–427 |year=1982 |isbn=0-88318-403-6 }}</ref> In its general form it looks like<ref name=Fischer>{{cite journal |first1=J. |last1=Fischer |first2=P. |last2=Saunders |first3=M. |last3=Sadli |first4=M. |last4=Battuello |first5=C. W. |last5=Park |first6=Y. |last6=Zundong |first7=H. |last7=Yoon |first8=W. |last8=Li |first9=E. |last9=van der Ham |first10=F. |last10=Sakuma |first11=Y. |last11=Yamada |first12=M. |last12=Ballico |first13=G. |last13=Machin |first14=N. |last14=Fox |first15=J. |last15=Hollandt |first16=M. |last16=Matveyev |first17=P. |last17=Bloembergen |first18=S. |last18=Ugur |url=http://www.bipm.org/wg/CCT/CCT-WG5/Allowed/Miscellaneous/Low_T_Uncertainty_Paper_Version_1.71.pdf |title=Uncertainty budgets for calibration of radiation thermometers below the silver point |journal=CCT-WG5 on Radiation Thermometry, BIPM, Sèvres, France |year=2008 |volume=29 |issue=3 |page=1066 |doi=10.1007/s10765-008-0385-1 |bibcode=2008IJT....29.1066S |s2cid=122082731 |display-authors=1 }}</ref>
<math display="block">S(T) = \frac{C}{\exp\left(\frac{c_2}{\lambda_x T}\right) - 1},</math>
where:{{Clarify|reason=what is S(T)?|date=June 2023}}
* <math>C</math> is the scalar coefficient
* <math>c_2</math> is the second radiation constant (0.014387752 m⋅K<ref>{{cite web |publisher=National Institute of Standards and Technology (NIST) |title=2006 CODATA recommended values |url=http://physics.nist.gov/cuu/index.html | date=Dec 2003 |access-date=Apr 27, 2010}}</ref>)
* <math>\lambda_x</math> is the temperature-dependent effective wavelength (in meters)
* <math>T</math> is the absolute temperature (in [[kelvin|K]])
== Planckian form ==
Line 26 ⟶ 39:
The Planckian form is realized by the following substitution:
Making this substitution renders the following the
; Sakuma–Hattori equation (Planckian form)
: <math>S(T) = \frac{C}{\exp\left(\frac{c_2}{AT + B}\right)-1}</math>
; First derivative<ref>''ASTM Standard E2758-10 – Standard Guide for Selection and Use of Wideband, Low Temperature Infrared Thermometers'', ASTM International, West Conshohocken, PA, (2010).
'''''<u>Updated</u>''''': ASTM E2758-15a(2021), https://www.astm.org/e2758-15ar21.html</ref>
: <math>\frac {dS}{dT} = \left[S(T)\right]^2 \frac{A c_2}{C\left(AT + B\right)^2}\exp\left(\frac{c_2}{AT + B}\right)</math>
=== Discussion ===
The Planckian form is recommended for use in calculating uncertainty budgets for [[radiation thermometry]]<ref name=Fischer/> and [[infrared thermometry]].<ref name="MSLNZ">''[http://msl.irl.cri.nz/sites/all/files/training-manuals/tg22-july-2009v2.pdf MSL Technical Guide 22 – Calibration of Low Temperature Infrared Thermometers]'' (pdf), Measurement Standards Laboratory of New Zealand (2008). '''''<u>Updated</u>''''': Version 3. July 2019, [https://www.measurement.govt.nz/download/28]</ref> It is also recommended for use in calibration of radiation thermometers below the silver point.<ref name=Fischer/>
The Planckian form resembles [[Planck's law
However the
This integral yields an [[incomplete polylogarithm]] function, which can make its use very cumbersome.
The standard numerical treatment expands the incomplete integral in a geometric series of the exponential
<math display="block">\int_0^{\lambda_2} \frac{c_1}{\lambda^5 \left[\exp\left(\frac{c_2}{\lambda T}\right)-1\right]} d\lambda
= c_1 \left(\frac{T}{c_2}\right)^4\int_{c_2/(\lambda_2 T)}^\infty \frac{x^3}{e^x -1} dx
</math>
after substituting <math>\lambda = \tfrac{c_2}{xT}, \ d\lambda = \tfrac{-c_2}{x^2 T dx}.</math> Then
<math display="block">\begin{align}
J(c)&\equiv \int_c^\infty \frac{x^3}{e^x -1}dx
=\int_c^\infty \frac{x^3 e^{-x}}{1- e^{-x}}dx \\[4pt]
&=\int_c^\infty \sum_{n\ge 1}x^3 e^{-nx} dx
\\[4pt]
&=\sum_{n\ge 1} e^{-nc} \frac{(nc)^3+3(nc)^2+6nc+6}{n^4}
\end{align}
</math>
provides an approximation if the sum is truncated at some order.
The Sakuma–Hattori equation shown above was found to provide the best curve-fit for interpolation of scales for radiation thermometers among a number of alternatives investigated.<ref name=Sakuma2>Sakuma F, Kobayashi M., "Interpolation equations of scales of radiation thermometers", ''Proceedings of TEMPMEKO 1996'', pp. 305–310 (1996).</ref>
The inverse Sakuma–Hattori function can be used without iterative calculation. This is an additional advantage over integration of Planck's law.
== Other forms ==
Line 73 ⟶ 95:
! Planckian
|-
|
| <math>S(T) = \frac{C}{\exp\left(\frac{c_2}{AT + B}\right)-1}</math>
| narrow
| yes
|-
|
| <math>S(T) = \frac{C}{\exp\left(\frac{A}{T^2} + \frac{B}{2T}\right)-1}</math>
| narrow
| yes
|-
|
| <math>S(T) = C \exp\left(\frac{-c_2}{AT + B}\right)</math>
| narrow
| no
|-
|
| <math>S(T) = \frac{C T^A}{\exp\left(\frac{B}{T}\right)-1}</math>
| broad and narrow
| yes
|-
|
| <math>S(T) = C T^A {\exp\left(\frac{-B}{T}\right)}</math>
| broad and narrow
| no
|-
|
| <math>S(T) = \frac{C}{\exp\left(\frac{c_2}{AT}\right)-1}</math>
| monochromatic
Line 113 ⟶ 135:
| no
|-
| Effective Wavelength
| <math>S(T) = C \exp\left(\frac{-A}{T}+\frac{B}{T^2}\right)</math>
| narrow
Line 125 ⟶ 147:
== See also ==
{{Div col|colwidth=20em}}
* [[Stefan–Boltzmann law]]
* [[Planck's law]]
* [[Rayleigh–Jeans law]]
* [[Wien approximation]]
* [[Wien's displacement law]]
* [[Kirchhoff's law of thermal radiation]]
* [[Infrared thermometer]]
* [[Pyrometer]]
* [[Thin-filament pyrometry]]
* [[Thermography]]
* [[Black body]]
* [[Thermal radiation]]
* [[Radiance]]
* [[Emissivity]]
* [[ASTM Subcommittee E20.02 on Radiation Thermometry]]
{{Div col end}}
== Notes ==
{{notelist}}
== References ==
<references/>
{{DEFAULTSORT:Sakuma-Hattori equation}}
[[Category:Statistical mechanics]]
[[Category:Equations]]
[[Category:1982 in science]]
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