Automatic Deformation Measurement Equipment for PZT Wafer

Abstract

PZT wafers are the core driving parts to adjust the laser resonant cavity length of laser gyro. Usually, the PZT wafers are used in pairs, and the paired PZT wafers need to have close piezoelectric coefficient. To handle the pairing and screening of PZT wafers, an automatic deformation measuring equipment is developed by using a cartesian-coordinate robot frame, in which multiple photoelectric sensors are used to detect the key motion position automatically. Besides, vacuum absorption technology is also used in picking, carrying and placing PZT wafers to protect them from accidental injury. When driving voltage is applied to PZT wafer, the resulting micro displacement is measured by dual opposite inductive probes with relative measurement principle. This measuring strategy eliminates the influence of placement error of PZT wafers on the final measuring result. Compared with the existing manual measurement, the efficiency can be improved by 60%. The experimental results show that the equipment has high reliability and consistency. The measurement accuracy in full scale is no more than 0.5 μm and the repeat accuracy is superior to 0.1 μm.