Birefringence is a phenomenon where a material splits incoming light into two rays traveling at different speeds due to having different refractive indices along different optical axes.
How it works:
- Occurs in anisotropic materials like calcite or quartz.
- When light enters such a material, it divides into an ordinary ray and an extraordinary ray, each experiencing a different refractive index.
- These rays travel at different velocities and exit the material with a relative phase shift, leading to double images or polarization effects.
Observable effects:
- A clear double image when viewing objects through birefringent crystals.
- Bright interference colors under crossed polarizers in polarized light microscopy.
Applications:
- Used in polarized light microscopy, optical mineralogy, LCD displays, and stress analysis through photoelasticity.