This paper presents the results of a study of the features of the formation of double conoscopic figures in total-internal-reflection prisms. The conditions for the existence of double conoscopic figures in the absence of a polarizer and analyzer are explained. An experiment has been done with prisms fabricated from crystals of calcite, potassium dihydrogen phosphate (KDP) and lithium niobate.
M. N. Litvinova, V. I. Stroganov, V. V. Krishtop, L. V. Alekseeva, and P. G. Pas'ko, "Double conoscopic figures in total-internal-reflection prisms," J. Opt. Technol. 73, 34-37 (2006)