1. See, for example, E. B. Priestley, P. J. Wojtowicz, and P. Sheng, Introduction to Liquid Crystals ( Plenum Press, New York, 1975 );
2. P. G. de Gennes, The Physics of Liquid Crystals (Oxford University Press, Oxford, 1974 ).
3. See, for example, I. C. Khoo and Y. R. Shen, Opt. Eng. 24, 579 (1985), and references therein.
4. J. W. Shelton and Y. R. Shen, Phys. Rev. A 5, 1867 (1972).
5. See, for example, Y. R. Shen, The Principles of Nonlinear Optics (J. Wiley, New York, 1984 ), Chapter 10.