Many materials have a well-characterized refractive index, but these indexes depend strongly upon the frequency of light. Standard refractive index measurements are taken at the "yellow doublet" sodium D line, with a wavelength of 589 nanometers.
There are also weaker dependencies on temperature, pressure/stress, etc., as well on precise material compositions (presence of dopants, etc.); for many materials and typical conditions, however, these variations are at the percent level or less. Thus, it is especially important to cite the source for an index measurement if precision is required.
In general, an index of refraction is a complex number with both a real and imaginary part, where the latter indicates the strength of absorption loss at a particular wavelengthâ€"thus, the imaginary part is sometimes called the extinction coefficient . Such losses become particularly significant, for example, in metals at short (e.g. visible) wavelengths, and must be included in any description of the refractive index.
List
See also
- Sellmeier equation
- Corrective lens#Ophthalmic material property tables
- Optical properties of water and ice
References
External links
- International Association for the Properties of Water and Steam
- Ioffe institute, Russian Federation
- Crystran, United Kingdom
- Jena University, Germany
- Hyperphysics list of refractive indices
- Luxpop: Index of refraction values and photonics calculations
- Kaye and Laby Online Provided by the National Physical Laboratory, UK
- List of Refractive Indices of Solvents
