Terms of RTE

Description

$\frac{1}{c}\frac{\partial I\left(r,\widehat{s},t\right)}{\partial t}$

No. of photons entering in volume of interest minus No. of photons emitting per unit time.

$\widehat{s}\cdot \nabla I\left(r,\widehat{s},t\right)$

Photon flux at point r travelling in given direction in given time.

${\mu }_t\left(r\right)I\left(r,\widehat{s},t\right)$

Reduction of Intensity of light (attenuation) in volume of interest.

${\mu }_t\left(r\right)={\mu }_a\left(r\right)+{\mu }_s\left(r\right)$

Total attenuation of light that is sum of absorption coefficients and scattering coefficients.

$p\left(\widehat{s}\cdot {\widehat{s}}^{\prime }\right)$

It is normalized phase function which represents probability density of scattering of light from direction $\widehat{s}$ to direction ${\widehat{s}}^{\prime }$ .

${\mu }_s\left(r\right){\displaystyle \underset{4\text{π}}{\overset{0}{\int }}p\left(\widehat{s}\cdot {\widehat{s}}^{\prime }\right)I\left(r,{\widehat{s}}^{\prime },t\right)\text{d}{\widehat{s}}^{\prime }}$

No. of photons scattered from direction $\widehat{s}$ into another direction ${\widehat{s}}^{\prime }$ .

$Q\left(r,\widehat{s},t\right)$

Source term which describe No. of photons emitted at point r per unit time in direction $\widehat{s}$ .