Measurement of Surface Acoustic Wave on a Quartz Ball with Proximate Electrodes to Improve Performance of Ball Surface Acoustic Wave Device

In order to improve the performance of ball surface acoustic wave (SAW) devices, we have developed an orientation control apparatus to find the Z axis of a quartz crystal ball by an optical birefringence measurement, and to find the X and Y axes by measuring the propagation characteristics of a SAW using an interdigital transducer (IDT), which is moved close to the ball using a translation stage. The soft spring of the vacuum chuck of the ball manipulator prevented damage to the ball or IDT during the contact. The concave shape of the ball holder of the chuck enabled repeatable alignment of the ball center and the manipulator axis. As a preliminary result, we confirmed that the SAW velocity variation had 60° periodicity and succeeded in identifying the -Y axis-equivalent direction on the quartz ball.