Optical property of a material that rotates the plane of polarised light.
An optical phenomenon where light is transmitted at slightly different speeds depending on the angle of incidence. Also light scattering due to different refractions created by impurities, defects, or stresses within the media substrate.
Reflection of light in two slightly different directions to form two rays
The property of some materials to split an incident beam into two beams polarised at right angles to each other.
A condition in an anisotropic medium in which two perpendicular polarizations in a fiber have different refractive indices and thus provide different group velocities.
splitting a ray into two parallel rays polarized perpendicularly
The numerical difference between the maximum and minimum refractive indices of anisotropic substances: ε-ω; nII-n┴; γ-α. Birefringence may also be determined by use of compensators, or estimated through use of the Michel-Lévy Interference Color Chart. Birefringence may be qualitatively expressed as low (0 - 0.010), moderate (0.010 – 0.050), or high (0.050); often birefringence 0.2 is termed “extreme”. “Strain birefringence” is a term used to refer to isotropic substances which exhibit uneven (usually) or spotty birefringence induced by mechanical, thermal, chemical, or other means.
A gemological term referring to the strength of double refraction in gemstones.
In optical discs, it is double refraction of light caused by improper cooling of the plastic from the injection molding process. High birefringence causes read errors and can only be detected with special equipment.
a double-refraction phenomenon in which an unpolarized beam of light is divided into two beams with different directions and relative velocities.
The phenomenon of double refraction of light wavefronts in a transparent, molecularly ordered material produced by the existence or orientation-dependent differences in refractive index. The term birefringence also commonly refers to the refractive index difference experienced by a transmitted wave through such a material. Wavefronts of light incident on a birefringent specimen are split into ordinary and extraordinary components that can recombine after emergence from the specimen to produce linearly, elliptically, or circularly polarized light.
having an index of refraction that is different for different polarization of light
Double light refraction. Certain types of material have this double refraction. The substrate used for CD-Rs has this property, and it is caused by the way the molecules are organized and by the internal tensions created when the disc is molded. Excessive birefringence can cause interference and read errors.
Optical distortion caused by different indices of refraction for separate directions of polarization, often caused by stress in the optical medium. Produced during CD or DVD injection molding by shrinkage, flow lines, and inclusions in the substrate. Usually more severe near the outer diameter.
the separation of a ray of light into two unequally refracted, polarized rays, occurring in crystals in which the velocity of light rays in not the same in all directions; numerically quantified as the difference between the greater and lesser refractive indices of the anisotropic crystal. Also called double refraction.
The separation of a light beam, as it penetrates a doubly refracting object, into two diverging beams, commonly known as ordinary and extraordinary beams. Learn more about Birefringence...
The numerical difference in refractive indices for a substance. In a given crystal view, the interference color (retardation) between crossed polars depends on the birefringence and thickness: Retardation (nm) = 1000 x thickness (m) x birefringence
Birefringence is another name for double refraction. In doubly-refractive stones, the light entering the stone is split into two light rays, and the rays travel in different paths. These stones have more than one refractive index. Calcite, peridot, zircon, tourmaline, and titanite are doubly-refractive stones.
Defined as ns-nf. Light traveling through a mineral is split into two rays, which travel at different speeds and have different indices of refraction: ns is the index of refraction of the slow ray, nf the index of the fast ray. Birefringence varies with the orientation of the mineral in the thin section, but a maximum value or a range of values for a certain mineral can be specified.
the splitting of a light wave into two unequally reflected or transmitted waves by an opticall anisotropic medium such as calcite or quartz. Also called double refraction.
difference between the refractive index of a fibre measured parallel to the fibre axis and that measured perpendicular to the fibre axis. Birefringence is frequently used as a measure of the orientation of the macromolecules within the fibre.
Double light refraction more...
The numerical difference in value between the highest and lowest refractive index of a mineral. This is not synonymous with interference colors. SEE INTERFERENCE COLORS.
Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on the polarization of the light. This effect can occur only if the structure of the material is anisotropic. If the material has a single axis of anisotropy, (i.e. it is uniaxial) birefringence can be formalised by assigning two different refractive indices to the material for different polarizations.