https://wiki.yanding.com/ 2026-07-11T05:28:43+00:00 https://wiki.yanding.com/ https://wiki.yanding.com/lib/tpl/myconfluence/images/favicon.ico text/html 2026-07-10T08:02:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:cie_luminous_efficiency_function&rev=1783670567&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) CIE Luminous Efficiency Function I. Definition The CIE luminous efficiency function $V(\lambda)$ is a standard response function established by the International Commission on Illumination (CIE) to describe the relative visual sensitivity of the $\Phi_{e,\lambda_m}$$\lambda_m$$\Phi_{e,\lambda}$$\lambda$$V(\lambda)$$L > 5 cd·m⁻²$$V(\lambda)$$CIE 1988… text/html 2026-07-10T08:02:50+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:illuminance&rev=1783670570&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Illuminance Illuminance Illuminance is a physical quantity that characterizes the amount of luminous flux received per unit area of an illuminated surface, directly reflecting the degree to which the surface is illuminated. Its magnitude depends on the luminous intensity of the light source, the irradiation distance, and the angle (following the inv… text/html 2026-07-10T08:02:53+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:irradiance&rev=1783670573&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Irradiance Definition: The radiant flux (power) incident on a surface per unit area, denoted by the symbol $E$$W / m^{2}$$$E = \frac{d\Phi}{dA}$$$I$$W/sr$$dA$$r$$dA$$d\Omega = \frac{dA}{r^2}$$d\Phi = I \cdot d\Omega = I \cdot \frac{dA}{r^2}$$E = \dfrac{d\Phi}{dA}$$$E = \frac{d\Phi}{dA} = \frac{I \cdot \dfrac{dA}{r^2}}{dA} = \frac{I}{r^2}$$ text/html 2026-07-10T08:02:48+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:luminance&rev=1783670568&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Luminance Luminance is a physical quantity that describes the brightness of a light-emitting body (or a reflecting/transmitting surface) in a specified direction. It is defined as the ratio of the luminous intensity in that direction to the projected area of the emitting surface perpendicular to that direction. It directly determines the human eye's … text/html 2026-07-10T08:02:50+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:luminous_efficacy&rev=1783670570&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Luminous Efficacy 1. Definition Luminous efficacy is a metric that measures the efficiency of a light source in converting energy into visible light. It is defined as the ratio of luminous flux ($\Phi_V$${lm·W}^{-1}$$K(\lambda)$$$K = \frac{\Phi_V}{\Phi_e} = \frac{\int_0^\infty K(\lambda)\Phi_{e,\lambda}\mathrm{d}\lambda}{\int_0^\infty \Phi_{e,\lambd… text/html 2026-07-10T08:02:48+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:luminous_exitance&rev=1783670568&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Luminous Exitance Luminous exitance (symbol: $M_v$, $M$) is a core physical quantity in photometry that characterizes the luminous properties of an area light source. It is used to quantify the ability of a surface to emit visible light outward, describing the total light output per unit area without considering the directional distribution of the em… text/html 2026-07-10T08:02:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:luminous_flux&rev=1783670569&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Luminous Flux Definition Luminous flux is a physical quantity in photometry used to measure the perceived power of light by the human eye. It represents the total luminous energy emitted by a light source per unit time, providing an intuitive indication of $$\Phi_{v}(\lambda)=K_{m}V(\lambda)\Phi_{e}(\lambda)$$$\Phi_{v}(\lambda)$$K_{m}$$V(\lambda)$$\… text/html 2026-07-10T08:02:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:luminous_intensity&rev=1783670569&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Luminous Intensity Definition Luminous intensity describes the intensity of a light source in a specific direction, defined as the luminous flux emitted per unit solid angle. It is an intrinsic property of the light source and is independent of the source area and observation distance.$$ I_v = \frac{\mathrm{d}\Phi_v}{\mathrm{d}\Omega} $$$I_v$$\Phi_v… text/html 2026-07-10T08:02:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:lv_luminance_exitance_conversion&rev=1783670567&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Conversion between Lv, Luminance, and Luminous Exitance Background: Expressing Film Speed on a Logarithmic Scale$$S_v = \log_2 (N S_x) \tag{1}$$$S_x$$S_v$$S_x$$S_v$$$E_v = A_v + T_v = B_v + S_v \tag{2}$$$A_v$$T_v$$B_v$$S_v$$$2^{E_v} = \frac{A^2}{T} = \frac{B S_x}{K} \tag{3}$$$$B = \frac{2^{E_v} \cdot K}{S_x} \quad (\textrm{fL}) \tag{4}$$$$1 \space\te… text/html 2026-07-10T08:02:51+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:radiance&rev=1783670571&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Radiance Radiance is defined as the radiant flux emitted by a radiation source in a given direction per unit projected area and per unit \(L\)\(\mathrm{W \cdot sr^{-1} \cdot m^{-2}}\)$$L = \frac{dI}{dA \cos\theta} = \frac{d^2 \Phi}{dA \cos\theta \, d\Omega}$$$L$$I$$\Phi$$A$$\theta$$\Omega$$L$$\rho$$$ M = \rho E $$$$ M = \pi L $$$$ L = \frac{\rho E}{\… text/html 2026-07-10T08:02:53+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:radiant_energy&rev=1783670573&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Radiant Energy I. Definition Radiant Energy is the energy carried by electromagnetic radiation during its emission, propagation, or absorption. It is a fundamental energy quantity in radiometry, used to characterize the total energy transferred by radiation, and is denoted by the symbol: $Q_e$$$Q_e = \int_{t_1}^{t_2} \Phi_e(t) dt$$$\Phi_e(t)$$t_1-t_… text/html 2026-07-10T08:02:54+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:radiant_energy_density&rev=1783670574&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Radiant Energy Density I. Definition Radiant energy density is defined as the electromagnetic radiant energy stored per unit volume of space\(w\)\(u\)\(J/m^3\)\([M L^{-1} T^{-2}]\)$$w = \frac{dQ}{dV}$$\(dQ\)\(dV\)$Q = 8000 J$$V= 23 L= 0.023 {m}^3$$w \approx 347\,826.09 {J/m}^3$\(E\)\(B\)$$w = \frac{1}{2}\left(\varepsilon E^2 + \frac{1}{\mu} B^2\righ… text/html 2026-07-10T08:02:52+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:radiant_exitance&rev=1783670572&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Radiant Exitance Radiant exitance, denoted as $M$, refers to the radiant flux emitted per unit time from a unit area of a surface into the outward hemispherical space, with the unit being $W/m^2$$$M = \frac{d\Phi}{dA}$$$$M = \int_{\Omega} L(\omega) \cos\theta \, d\omega$$$L(\omega)$$\omega$$\theta$$\Omega$$$M = \rho E$$$\rho$$E$$\mathrm{W/m^2}$$$M = … text/html 2026-07-10T08:02:54+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:radiant_flux&rev=1783670574&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Radiant Flux Radiant flux is the rate of change of radiant energy with respect to time, representing the total radiant energy (power) emitted, transferred, or received per unit time. It is denoted by the symbol $\Phi$$P$$$\Phi_\text{e} = \frac{\mathrm{d}Q_\text{e}}{\mathrm{d}t}$$$Q_\text{e}$$t$$\Phi$$O$$l_0$$R$$\mathrm{d}A$$$\mathrm{d}P = E\mathrm{d}… text/html 2026-07-10T08:02:52+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:radiant_intensity&rev=1783670572&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Radiant Intensity Definition: The radiant flux emitted by a radiation source in a specific direction per unit solid angle, denoted by the symbol $I$$$I = \frac{d\Phi}{d\Omega}$$$\Omega$$A$$r$$\Omega = \frac{A}{r^2}$$\Phi $$\Omega$$ I = \frac{d\Phi}{d\Omega}$$D$$ I = \frac{d\Phi}{d\Omega}$ text/html 2026-07-10T08:02:51+00:00 Anonymous (anonymous@undisclosed.example.com) https://wiki.yanding.com/doku.php?id=en:yanding:imaging_basics:optics:radiometry_photometry:solid_angle&rev=1783670571&do=diff FIXME This page is not fully translated, yet. Please help completing the translation. (remove this paragraph once the translation is finished) Solid Angle Definition: If an object of arbitrary shape subtends a region at the center of a sphere, and its projected area on a spherical surface of radius r is A, then the solid angle (denoted by the symbol $\Omega$$$\Omega = \frac{A}{r^2}$$