零差移频式干涉图形相位锁定系统的超精密控制

Ultra-precision control of homodyne frequency-shifting interference pattern phase locking system

利用全息曝光法制造大口径全息平面光栅时,常引入零差移频式干涉图形相位锁定系统来提高全息曝光质量。本文针对直接影响最终干涉曝光精度的系统控制精度开展研究。首先,介绍了新型的零差移频式干涉图形锁定系统的原理和结构,在系统理论建模及模型辨识的基础上,针对非线性系统模型进行了高阶线性化拟合,并结合系统振动测试实验结果,设计了系统控制器。然后,对设计的控制器进行了实际控制调试,实现了系统的超精密控制。最后,针对系统控制误差纹波,采用频域分析方法揭示了影响系统控制精度的主要因素,提出了未来提升系统控制精度的方法。测试结果显示:系统相位锁定控制精度可达±0.046 1rad(3σ)且以高频误差纹波形式呈现。分析了高频误差纹波的成因,指出受系统噪声、延迟、控制器参数等因素限制,控制器很难完全抑制频段跨度大而连续的高频微振动引起的干涉图形相位漂移。

When larger aperture holographic plane gratings are fabricated by the holographic exposure method, the homodyne frequency-shifting interference pattern phase locking system usually is used to improve the holographic exposure quality. This paper focuses on the ultra-precision control of the system. Firstly, the principles and structures of a novel homodyne frequency-shifting interference pattern phase locking system were introduced. The high-order linear model was fitted for a nonlinear model of the system based on the theoretical modeling and system identification and a controller of the system was designed by combining the fitting model and the system vibration test result. Then, an actual controlling test was performed based on the design result of the controller to implement the ultra-precision control of the system. Finally, an analysis method on frequency domain was used to explore the effect factors on control precision for the ripple wave in the system. The experiment results demonstrate that the controlling error of the system has reached to ±0. 046 1 rad（3a） and it shows high frequency error ripple wave. The causes of the high frequency error were researched, and the results indicate that limited to the noise, delay of the system and controller parameters, the drift of the interference pattern caused by continuous micro-vibration with a wide frequency range can not be completely restrained by the controller.