Three-dimensional birefringence imaging with a microscope tilting-stage. I. Uniaxial crystals

The development of a microscope tilting-stage suitable for use with birefringence imaging is described, thus enabling precise three-dimensional birefringence information of uniaxial crystals to be obtained. Equations have been derived for uniaxial crystals in any orientation. The technique enables precise values of the birefringence Δn=ne−no(difference between extraordinary and ordinary refractive index) and orientation of the optic axis to be obtained. The sign of the optical indicatrix may be unambiguously identified. The method is also able to obtain information on preferred orientation in a polycrystalline material. In addition to this, an unknown crystalline material may be identified, or at least classified within a specific group of crystalline materials.