横向压电驱动变形镜的迟滞特性及其闭环校正

Hysteresis characteristics and closed loop correction of unimorph deformable mirror

横向压电驱动变形镜在自适应光学系统中应用广泛,其利用了压电陶瓷的横向逆压电效应驱动镜片实现变形。在高电场强度下变形镜迟滞曲线存在特殊的"蝴蝶形",增加了控制难度,且变形镜无法正常工作。针对这一问题利用压电陶瓷极化及铁电材料的电滞回线理论进行了分析,明确了蝶形曲线产生的原因。通过实验确定了变形镜矫顽场强度在-500^-400 V/mm之间,迟滞曲线回归一般的"柳叶"形状。根据迟滞曲线的特点设计了静态的PID闭环校正系统,并进行了校正实验。结果表明,闭环校正后线性度得到明显提升,迟滞率可降低至1.8%。

The unimorph deformable mirror(DM)is widely applied in adaptive optics,which utilizes the lateral reverse piezoelectric effect of piezoelectric ceramics to drive the mirror to deform.The hysteresis curve of the deformable mirror is a special"butterfly shape"in the high electric field strength,which increases the difficulty of control,and the deformable mirror cannot work normally.The theory of piezoelectric ceramic polarization and the hysteresis loop of ferroelectric materials were analyzed so that the cause of the butterfly curve could be confirmed.The experimental results show that the covariate field of the DM is between-500 and-400 V/mm,and the hysteresis curve is normalized willow shape.Then a static PID closed loop correction system was designed for the characteristics of the hysteresis curve,and the correction experiment was carried out.The results show that the linearity is obviously improved,and the hysteresis rate is reduced to 1.8%by the PID closed loop correction.