ACTIVE CONTROL OF LITHIUM-NIOBATE SINGLE-CRYSTALS FOR CLASSIFICATION BY THE VELOCITIES OF ACOUSTIC SURFACE-WAVE

For the industrial manufacture of crystals, the technique of measuring the angle of the scalar synchronism of second optical harmonic generation (SHG) is suggested. A correlation has been found between the scalar synchronism angle of SHG in a layer of a crystal and the velocity of acoustic surface wave (ASW) in a plate cut from that layer. The derived relationship makes it possible to predict the ASW velocity on a free surface prior to a single-crystal boule cut into plates.