What is induced birefringence?
Field-induced birefringence is used to change the polarization state of a light beam and can be used for both modulation and shuttering. From: Encyclopedia of Physical Science and Technology (Third Edition), 2003.
What is stress induced birefringence?
When mechanical stress is applied to isotropic materials, residual birefringence is generated. This birefringence is linearly proportional to the stress in the material. 1. In precise polarization optics, large stress can change the polarization state of the light.
What is birefringence also known as?
double refraction, also called birefringence, an optical property in which a single ray of unpolarized light entering an anisotropic medium is split into two rays, each traveling in a different direction.
What causes mineral birefringence?
A value, termed birefringence, describes the difference in velocity of the two rays. When the rays emerge from the grain, they combine to produce interference colors.
How is birefringence used for material identification?
Many minerals exhibit birefringence, which is a directional dependence of the speed of light through the mineral. This phenomenon is used by petrologists to identify minerals in a thin section (≤ 1 mm) where a sample illuminated by polarized light is rotated under a microscope to reveal its birefringence.
What is meant by a negative birefringence?
Negative birefringence means that Δn = ne − no is less than zero. In other words, the polarization of the fast (or slow) wave is perpendicular to the optic axis when the birefringence of the crystal is positive (or negative, respectively).
Is birefringence refractive index?
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive).
What does birefringent mean gout?
Under polarized light, gout crystals appear needle-shaped and yellow, a property called negative birefringence. If crystals in joint fluid cannot be established, your healthcare provider may still be able to make a diagnosis of gout based on your history, X-rays, and physical exam findings.
What is application of birefringence?
Birefringence has several applications. It can be used to find defects in the manufacturing process, or identify weak spots in plastic structure manufactured via injection molding. It is also used extensively in optical communications to change linearly polarized light into circularly polarized one and vice versa.
What is the unit of birefringence?
We measure the birefringence caused by the residual stress in a sample piece. Typically the Birefringence is indicated as the decrease per 1cm in (Unit = nm / cm). As a high precision measurement, we can also show the direction of fast axis in addition to the stress birefringence.
What does negative and positive birefringence mean?
Positive or negative Negative birefringence means that Δn = ne − no is less than zero. In other words, the polarization of the fast (or slow) wave is perpendicular to the optic axis when the birefringence of the crystal is positive (or negative, respectively).
Why does induced birefringence remain after removing the external field?
The temporary application of such a field can even cause a frozen-in polarization, which means that the induced birefringence remains even after removing the external field.
What is the birefringence induced in the rectangular bar?
The birefringence induced in the rectangular bar by the vibration of the piezoelectric transducer varies with time and is a maximum in the center of the optical bar. Fig. 3.23 B illustrates the effect of the PEM on a linearly polarized beam that is incident at 45° to the modulator axis (horizontal plane).
What is the origin of the birefringence effect?
This effect was first described by the Danish scientist Rasmus Bartholin in 1669, who observed it in calcite, a crystal having one of the strongest birefringences.
What is the effect of mechanical stress on birefringent materials?
However, when they are under mechanical stress, birefringence results. The stress can be applied externally or is “frozen in” after a birefringent plastic ware is cooled after it is manufactured using injection molding.