What is isotropic indicatrix?

The Isotropic Indicatrix The optical indicatrix is simply a three dimensional object constructed by drawing vectors of length proportional to the refractive index for light vibrating parallel to the vector direction from a central point. The ends of all of the vectors are then connected to form the indicatrix.

What are isotropic minerals?

Isotropic minerals are minerals that have the same properties in all directions. This means light passes through them in the same way, with the same velocity, no matter what direction the light is travelling. There are few common isotropic minerals; the most likely ones to see in thin section are garnet and spinel.

What is indicatrix in optical mineralogy?

The optical indicatrix is a geometrical solid relating the refractive index of a mineral to the mineral’s structure. The surface of the indicatrix represents the different refractive indices in the crystal.

What is uniaxial indicatrix?

The uniaxial indicatrix is constructed by first orienting a crystal with its c-axis vertical. This circle is referred to as the circular section of the uniaxial indicatrix. Light propagating along directions perpendicular to the c-axis or optic axis is broken into two rays that vibrate perpendicular to each other.

How does the indicatrix of an isotropic crystal work?

INDICATRIX OF ISOTROPIC CRYSTALS Since velocity is proportional to l/ n , and n remains constant at all directions the indicatrix will be a sphere with a radius of n (FIG. 6.2). Any section cut through the indicatrix representing a section cut parallel to that direction of the isotropic mineral will produce a circle.

What kind of shape is an optic indicatrix?

By thus representing the minerals, three types of geometric shapes appear: -For some minerals, the optic indicatrix is a sphere. This is the case of those that are isotropic. – For others, it is an ellipsoid of revolution (with two principle axes), which are known as uniaxial anisotropic minerals.

What are the optical properties of Isotropic minerals?

OPTICAL PROPERTIES OF ISOTROPIC MINERALS RVS OF ISOTROPIC CRYSTALS The velocity of light (1/ n ) is same in all directions in isotropic substances ie., gases liquids, amorphous solids; like glass and minerals crysallizing in isometric or cubic system. Therefore, the RVS

How is the refractive index related to the direction of propagation?

As the refractive index varies with the direction of vibrationof the light waves for most crystals, it is of great assistance to visualisethe values of “n” for all the directions of vibration and relatethem to the directions of propagation, which will be perpendicular. Thegeometric figure which results is called the optic indicatrix.