In optics and spectroscopy, transmittance is the fraction of incident light at a specified wavelength that passes through a sample.

$T\; =\; \{I\backslash over\; I\_\{0\}\}$

where $I\_0$ is the intensity of the incident light and I is the intensity of the light coming out of the sample. The transmittance of a sample is usually given as a percentage, defined as

$T\backslash \%\; =\; \{I\backslash over\; I\_\{0\}\}\; *\; 100\backslash \%$

Transmittance is related to absorbance A as

$A\; =\; -\; \backslash log\_\{10\}T\backslash \; =\; -\; \backslash log\_\{10\}\{I\backslash over\; I\_\{0\}\}\backslash ,$

$A\; =\; 2\; -\; \backslash log\_\{\}T\backslash \%\backslash ,$

where T% is the percent transmittance and T is "per one" transmittance. Note that the term transmission refers to the physical process of light passing through a sample, whereas transmittance refers to the mathematical quantity.

Optics | Spectroscopy

Transmission_%28Physik%29 | Transmitencia | Transmittance | Trasmittanza