index of refraction

A measure of the optical density of a transparent material such as glass or the cornea. It is the ratio of the speed of light through the material to its speed in a vacuum.

Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

Index of refraction

A constant number for any material for any given color of light that is an indicator of the degree of the bending of the light caused by that material.

Mentioned in: Eye Glasses and Contact Lenses

index of refraction

The ratio of the speed of light in a vacuum or in air, c, to the speed of light in a given medium, v. Symbol: n. Hence,

n = c/v

The speed of light in a given medium depends upon its wavelength. Consequently, the index of refraction varies accordingly, being greater for short wavelengths (blue) than for longer wavelengths (red). The index of refraction forms the basis of Snell's law, which quantitatively determines the deviation of light rays traversing a surface separating two media of different refractive indices. Syn. refractive index. Plural: indices. See dispersion; law of refraction; gradient-index lens; high index lens; speed of light; refractometer.

Table I3 Refractive indices of some transparent media at selected wavelengths
spectral line	G	F	D	C	A
Origin	Calcium	Hydrogen	Sodium	Hydrogen	Oxygen
wavelength (nm)	430.8	486.1	589.3	656.3	759.4
aqueous or vitreous humour	1.3440	1.3404	1.3360	1.3341	1.3317
crystalline lens	1.4307	1.4259	1.4200	1.4175	1.4144
spectacle crown	1.5348	1.5293	1.5230	1.5204	1.5163
dense flint	1.6397	1.6290	1.6170	1.6122	1.6062

Table I4 Index of refraction n of various media for sodium light (λ = 589.3)
air	1.00
water (at 20ºC)	1.333
spectacle crown glass	1.523
flint glass (dense)	1.62
flint glass (extra dense)	1.65-1.70
titanium oxide glass	1.701
calcite crystal
ordinary ray	1.658
extraordinary ray	1.486
quartz crystal
ordinary ray	1.544
extraordinary ray	1.553

diamond	2.42
Canada balsam	1.53-1.54
CR-39	1.498
polycarbonate	1.586
silicone rubber	1.44
CAB	1.47
PMMA	1.49
HEMA	1.43
hydrogel polymer
20% water content	1.46-1.48
75% water content	1.37-1.38
eye
tears	1.336
cornea	1.376
aqueous humour	1.336
crystalline lens (average effect)	1.42
vitreous humour	1.336

Mentioned in

References in periodicals archive

Hence, according to (22), the index of refraction depends on the position (r).

Interactions in an Acoustic World: Dumb Hole

1: The change for the index of refraction of the vacuum (n-1) versus the temperature of the superconductor (T).

Vacuum Polarization by Scalar Field of Bose-Einstein Condensates and Experimental Design with Laser Interferences

depending on [sigma], such that there exists an interior transmission eigenvalues of the index of refraction n', in [sigma]-neighborhood of each [k.sub.j], whenever [eta] is small enough.

On Certain Translation Invariant Properties of Interior Transmission Spectra and Their Doppler's Effect

[13] Austin RW, Halikas G (1976) The Index of Refraction of Seawater, Vol.

Immersion Coefficient for the Marine Optical Buoy (MOBY) Radiance Collectors

Beyond the limitations related to the RTE itself, one can blame the imprecision of several of the input parameters such as the pigments' index of refraction, their size, and shape distributions or the reflection coefficients at the air/film and film/substrate interfaces.

Theoretical study and experimental analysis of the scattering efficiency of hollow polymer particles in the dependent light scattering regime

The square of the index of refraction with the addition of nonlinear terms becomes

Effects of nonlinearity on wave propagation in fiber Bragg gratings

(d) The modeling of dependent light scattering effects in dense media strongly depends on the value of the relative index of refraction of the system: (1) For low nr, the use of single coherent scattering approximation can lead to a fairly accurate modeling provided the particles' shape can be approximated by spheres and that their spatial correlation is mainly driven by a hard sphere potential.

Dependent light scattering in white paint films: clarification and application of the theoretical concepts

Nonetheless, this paper largely addresses negative index of refraction, as it serves as an observable milestone and a proof of concept in science's ability to steer and otherwise manipulate light, which is essential for achieving a cloaking capability.

The Cheshire jet: harnessing metamaterials to achieve an optical stealth capability

The index of refraction is a fundamental property of a substance, and its determination may provide valuable diagnostic information about minerals and crystals.

The refractometer

All known materials have index of refraction which is more than one however in 1968 Veselago [1] found that it is possible to make a material that has index of refraction less than one, even negative.

Highly directive patch antenna using planar metamaterial

Future applications in optical circuit elements and the boosting output power of LEDs are described, and the chapter on the optical properties of ZnO discusses methods for measuring the index of refraction, among other issues.

Wide bandgap light emitting materials and devices