X. Wang, J. Y. Zhang, T. E. Milner, J. F. de Boer, Y. Zhang, D. H. Pashley, and J. S. Nelson, "Optical birefringence imaging of dentin and enamel," in Advances in Optical Imaging and Photon Migration, J. Fujimoto and M. Patterson, eds., Vol. 21 of OSA Trends in Optics and Photonics (Optical Society of America, 1998), paper AMC6.