An ultrasonic X-Y stage using 10 MHz surface acoustic waves

We have succeeded in operation of an ultrasonic linear motor using Rayleigh waves. We used 3 inch 127.8° Y-cut LiNbO₃ wafers. Four IDTs were arranged to excite x-propagation waves and y-propagation waves in both directions. The dimensions of the IDTs were 25 mm aperture size, 400 μm pitch, 100 μm strip width and 10 pairs. The operation area was about 25 mm square. The driving frequency was about 9.6 MHz in the x-direction and about 9.1 MHz in the y-direction. The most important point of the success was the shape of the contact surface and the slider material. For the contact materials, small balls about 1 mm in diameter are introduced to obtain high contact pressures around 100 MPa. We tried ruby balls, steel balls and tungsten carbide balls. Each slider has three balls to get stable contact at three points. The maximum transfer speed was about 20 cm/sec. The transfer speed was controllable by changing the driving voltage