- Mathematical definitions Radiant exposure Spectral exposure
- SI radiometry units
- See also
- References
In radiometry, radiant exposure or fluence is the radiant energy received by a surface per unit area, or equivalently the irradiance of a surface, integrated over time of irradiation, and spectral exposure or is the radiant exposure per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength. The SI unit of radiant exposure is the joule per square metre ({{nobreak|J/m2}}), while that of spectral exposure in frequency is the joule per square metre per hertz ({{nobreak|J⋅m−2⋅Hz−1}}) and that of spectral exposure in wavelength is the joule per square metre per metre ({{nobreak|J/m3}})—commonly the joule per square metre per nanometre ({{nobreak|J⋅m−2⋅nm−1}}).
Mathematical definitions
Radiant exposure
Radiant exposure of a surface, denoted He ("e" for "energetic", to avoid confusion with photometric quantities), is defined as[1]
where
- ∂ is the partial derivative symbol;
- Qe is the radiant energy;
- A is the area;
- T is the duration of irradiation;
- Ee is the irradiance.
Spectral exposure
Spectral exposure in frequency of a surface, denoted He,ν, is defined as[1]
where ν is the frequency.
Spectral exposure in wavelength of a surface, denoted He,λ, is defined as[1]
where λ is the wavelength.
SI radiometry units
{{SI radiometry units}}See also
- Exposure (photography)
- Radiant energy
- Irradiance
References
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