Utilization of the second-harmonic generation in the determination of the symmetry of crystals

A consideration is given to the possibility of using the frequency doubling of laser radiation in proving that a given crystal has no inversion center (i.e., that it is noncentrosymmetric). The data for a large number of organic compounds obtained by this method are compared with the results of x-ray diffraction and piezoelectric investigations. It is shown that the absence of a center of inversion (acentrism) of a crystal can be determined conveniently by the second-harmonic method.