Explanation

It usually occurs in anisotropic materials, such as some crystal or orientation polymer. When the natural light beam enters these materials, the light wave propagates in different directions at different speeds, leading to the appearance of refracted light. In orientation polymer, this phenomenon can be measured by the birefringence of light to analyze the degree of orientation of materials. When light wave propagates in polymer, because of its anisotropy, it will lead to different refractive index in different directions. This leads to different refractive directions of light waves, resulting in birefringence. birefringence is a common method for measuring the degree of orientation of polymer. In this method, the main refractive index (along the orientation direction) and secondary refractive index (perpendicular to the orientation direction) of a polymer can be directly measured by placing the polymer in an immersion solution and observing its optical behavior under a polarized light microscopy. These values can be used to calculate birefringence, typically represented as Δ N=n ∨ - n ‖, where n ∨ represents the refractive index perpendicular to the orientation direction, and n ‖ represents the refractive index parallel to the orientation direction.

Classification