The results of light and ultrasound research in crystals with optical activity are discussed and analyzed in this paper. The conditions under which the degeneration of Bragg synchronism by the angles of the falling light beams takes place have been determined. It was shown that high bandwidth can retain in the relatively wide angle range under fixed values of light and sound vectors.

In this report the results of work [1] are developed. In [1] the analytic expressions are found that show that in crystals with optical activity, apart from ordinal Bragg synchronism of anizotropic diffraction, there are two additional Bragg synchronisms stipulated by the presence of optical activity.