Most of the materials have a well-characterized refractive index, but these indices often depend strongly upon the frequency of light, causing optical dispersion. Standard refractive index measurements are taken at the "yellow doublet" sodium D line, with a wavelength (λ) 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's 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 wavelength—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
+ Some representative refractive indicesName of materialλ (nm)Refractive index no. nReferenceVacuum 1 (by definition) Air at STP 1.000273 See fig. 1.Gases at 0 °C and 1 atmHelium589.291.000036Hydrogen589.291.000132Air589.291.000293Carbon dioxide589.291.00045Liquids at 20 °CWater589.291.33310% glucose solution in water589.291.3477Acetone 1.36Ethanol (ethyl alcohol)590.291.36120% glucose solution in water589.291.3635Silicone oil (nD)589.291.393–1.40360% glucose solution in water589.291.4394Kerosene 1.44Carbon tetrachloride589.291.461Benzene589.291.501Carbon disulfide589.291.628Arsenic trisulfide and sulfur in methylene iodide 1.9Meyrowitz, R, A compilation and classification of immersion media of high index of refraction, American Mineralogist 40: 398 (1955) Solids at room temperatureFused silica (a pure form of glass, also called fused quartz)589.291.458Sodium chloride589.291.544Amber589.291.55Tantalum pentoxide589.292.15Strontium titanate589.292.41Diamond589.292.417Titanium dioxide (rutile phase)589.292.614Silicon carbide (moissanite; 6H form) 589.292.65 Other materialsLiquid helium 1.025Perfluorohexane (Fluorinert FC-72) 1.251 Water ice 1.31TFE/PDD (Teflon AF) 1.315 Cryolite 1.338Cytop 1.34 Polytetrafluoroethylene (Teflon) 1.35–1.38 Sugar solution, 25% 1.3723Cornea (human) 1.373/1.380/1.401 Lens (human) 1.386–1.406Liver (human)9641.369 Intestinal mucosa (human)9641.329–1.338 Ethylene tetrafluoroethylene (ETFE) 1.403 Sylgard 184 (polydimethylsiloxane) 1.4118 Sugar solution, 50% 1.4200Polylactic acid 1.46Pyrex (a borosilicate glass) 1.470Vegetable oil 1.47Index Of Refraction Of Vegetable Oil, The Physics Factbook.Glycerol 1.4729 Sugar solution, 75% 1.4774Poly(methyl methacrylate) (PMMA) 1.4893–1.4899Halite (rock salt) 1.516Plate glass (window glass) 1.52"High temperature glass melt property database for process modeling"; Eds.: Thomas P. Seward III and Terese Vascott; The American Ceramic Society, Westerville, Ohio, 2005, Crown glass (pure) 1.50–1.54PETg 1.57Polyethylene terephthalate (PET) 1.5750Polycarbonate 150 1.60C. R. Garcia, J. Correa, D. Espalin, J. H. Barton, R. C. Rumpf, R. Wicker, V. Gonzalez, "3D Printing of Anisotropic Metamaterials," PIER Lett, Vol. 34, pp. 75–82, 2012.Crown glass (impure) 1.485–1.755Flint glass (pure) 1.60–1.62Bromine 1.661Flint glass (impure) 1.523–1.925Sapphire 1.762–1.778Boron nitride 2–2.14Cubic zirconia 2.15–2.18Potassium niobate (KNbO3) 2.28Zinc oxide3902.4Cinnabar (mercury sulfide) 3.02 Birefringent: nω = 2.905 nε = 3.256Silicon 1200 - 8500 3.42–3.48Gallium(III) phosphide 3.5Gallium(III) arsenide 3.927 Germanium3000 - 16000 4.05–4.1
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