[[File:Dichroic filters.jpg|thumb|right|[[Dichroic filter]]s are created using optically transparent materials.]]
In the field of [[optics]], '''transparency''' (also called '''pellucidity''' or '''diaphaneity''') is the [[physical jnihilhkihlihilhproperty]] of allowing [[light]] to pass through the material without appreciable [[light scattering by particles|scattering of light]]. On a [[macroscopic scale]] (one in which the dimensions are much larger than the wavelengths of the [[photon]]s in question), the photons can be said to follow [[Snell's law]]. '''Translucency''' (also called '''translucence''' or '''translucidity''') allows light to pass through but does not necessarily (again, on the macroscopic scale) follow Snell's law; the photons can be scattered at either of the two interfaces, or internally, where there is a change in the index of [[refraction]]. In other words, a translucent material is made up of components with different indices of refraction. A transparent material is made up of components with a uniform index of refraction.<ref>{{cite journal |last=Thomas |first=S. M. |title=What determines whether a substance is transparent? |journal=[[Scientific American]] |date=October 21, 1999}}</ref> Transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant [[spectrum]] of every color. The opposite property of translucency is [[Opacity (optics)|opacity]]. Other categories of visual appearance, related to the perception of regular or diffuse reflection and transmission of light, have been organized under the concept of [[Cesia (visual appearance)|cesia]] in an order system with three variables, including transparency, translucency and opacity among the involved aspects.
When light encounters a material, it can interact with it in several different ways. These interactions depend on the [[wavelength]] of the light and the nature of the material. Photons interact with an object by some combination of reflection, absorption and transmission.
