What are optical properties of liquid crystals?
A true liquid is isotropic , meaning that its properties are uniform in all directions— the result of its molecules being in constant random motion. Crystalline solids, in contrast, are anisotropic ; optical- and other properties such as thermal and electrical conductivity vary with direction.
What is birefringence in optical fiber?
Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. The birefringence is often quantified as the maximum difference between refractive indices exhibited by the material.
Are liquid crystals optically active?
Optical activity of matter is related to the chirality of its constitutive molecules. In liquid crystals, chiral molecules can give rise to superstructures in which the local dielectric tensor rotates in space describing a helix, a fact which greatly enhances the optical activity of the medium.
What is the optic axis of a birefringence crystal?
An optic axis of a crystal is a direction in which a ray of transmitted light suffers no birefringence (double refraction). An optical axis is a direction rather than a single line: all rays that are parallel to that direction exhibit the same lack of birefringence.
What is meant by optical properties?
Optical properties characterize the response of materials to incident electromagnetic radiation. For each material, the incident radiation is partially transmitted, partially reflected and partially absorbed.
How will you differentiate liquid crystals from pure liquids?
Liquids can flow, for example, while solids cannot, and crystalline solids possess special symmetry properties that liquids lack. Liquid crystals share with liquids the ability to flow but also display symmetries inherited from crystalline solids.
What is the birefringence of quartz?
Quartz belongs to the trigonal crystal class and accordingly is uniaxial. It is called uniaxial positive because ne > no. The optical axis in quartz corresponds to the c-axis of the unit cell, so there is no birefringence when light passes the crystal from tip to tip.
How is birefringence measured?
Birefringence is measured as the difference of indices of the refraction of the components within the material. An “average” or “normalized” birefringence for a sample is sometimes computed by dividing the measured retardation magnitude by the thickness of the sample.
How optical activity is a constitutive property?
(iv) Additive and Constitutive Properties: Additive and constitutive properties are physical properties that are dependent on the number of atoms in a molecule as well as their constitution. Optical activity is a property that is constitutive. The dipole moment is a constitutive and additive property.
How do you find the optic axis of a crystal?
The optic axis is located by finding the principal directions of the two wedge faces and subsequently solving three spherical triangles.
How do you classify optical materials?
Various kinds of optical material are used for a large number of applications, including transparent glasses and ceramics with specific transmission, reflection, and absorption properties for shielding applications; impurity-doped dielectric crystals, ceramics, and glasses as well as semiconductors for solid state …
Which of these is optical property?
Among the optical properties, refraction, absorption, reflection, and scattering of light are the most important.