SPECIFIC DIRECTIONS OF PLANE ELASTIC-WAVES IN THIN QUARTZ CRYSTAL PLATES

When plane elastic waves are propagated in crystals, the three mechanical displacements corresponding to the three types of waves are mutually perpendicular and in the most general case none of them is normal or parallel to the wave front. However, when the waves are able to propagate in specific directions, these values show pure modes. This paper describes an investigation of the specific directions of the wave propagations in thin quartz crystal plates. Some experiments based on the calculated results are given and the measured values coincide well with the calculated ones.