Kf. Warnick et Dv. Arnold, SECONDARY DARK RINGS OF INTERNAL CONICAL REFRACTION, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 55(5), 1997, pp. 6092-6096
This paper treats the phenomenon of internal conical refraction, in wh
ich a narrow beam propagating along an optical axis of a biaxial aniso
tropic medium spreads into a hollow cone. An expression is obtained fo
r the intensity distribution produced by conical refraction that predi
cts additional fringes concentric to the well-known Poggendorf dark ri
ng for certain propagation distances and beam widths.