Use this Optical Density (OD) Calculator to convert between intensities (I0 and I), transmittance (T), percent transmittance (%T), and optical density/absorbance (OD or A). You can also optionally use Beer-Lambert law to solve for concentration, path length, or. Optical Density (OD) is a logarithmic measurement of how much light is blocked when passing through an optical filter, lens, or material. Because it is logarithmic, OD values are additive: stacking an OD 2 filter and an OD 3 filter results in a total attenuation of OD 5. This relationship is fundamental in spectroscopy and photometry. If you like this. This calculator computes the power reflectivity and transmission of a plan wave at a dielectric interface using the Fresnel equations.
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