Study on Optical Servosystem

1.光伏效应的机理。提出了PLZT元件中光伏效应的电学模型，明确了PLZT元件中光伏效应的机理。该模型由依赖于光强的电流源、依赖于光强和元件温度的电阻以及依赖于温度的电容并联构建。实验证明了该模型的有效性。PLZT元件特性的改进。从电模型可以估计出PLZT元件具有非常慢的二阶响应速度。通过在PLZT元件表面叠加加热光引起的热电效应，可以显著提高响应速度的上升时间，通过控制加热光的照射时间，也可以提高响应的稳定时间。实验表明，掺杂0.5 mol%的W对响应速度的影响大于响应速度，需要进一步优化掺杂方式以提高响应速度。光伺服系统控制方法的发展。提出了双晶圆型光学执行器的位移控制方法。在简单的开关控制中，由于系统中用于控制辐照时间的光学快门具有严重的时滞特性，在阶跃响应中会引起较大的平稳振荡。研究了另外两种方法来弥补这一弱点。一种是通过考虑致动器的电流位移、电流速度和与之相关的阈值来控制辐照时间的方法。另一种是预测控制，其中通过考虑当前位移和光学快门的时间滞后来预测照射时间。实验表明，预测控制是三种方法中最适用的一种。从这些结果可以看出，使用PLZT元件的光学驱动器适用于光伺服系统，如果将其进一步深入研究。少

1.Mechanism of Photovoltaic Effect.The electric model for the photovoltaic effect in PLZT element is proposed to make clear the mechanism of the photovoltaic effect in it. The model is constructed in parallel by an electric current source dependent on the light intensity, electric resistance on the light intensity and the temperature of the element, and the electric capacitance on the temperature. The validity of this model is shown by the experiment.2.Inprovement of Characteristics of PLZT Element.It can be estimated from the electric model that the PLZT element has the very slow response speed of second ordor. The rise time of the response speed can be considerably improved by the superposition of the pyro-electric effect caused by irradiating the light for heating on the surface of the PLZT element, and the settling time of the response is also improved by controlling the time to irradiate the light for heating. It is clarified by the experiment that the doping of W of 0.5 mol% impr … More oves the response speed, and the optimization of the doping should be investigated for the improvement.3.Development of Control Method in Optical Servosystem.Some control methods of the displacement of the bimorph type optical actuator are developed. In a simple On-Off control some large stationary oscillation is caused in the step response because the optical shutter in the system necessary for control of the irradiating time has severe time lag characteristic. The other two methods are studied to compensate the weak point. The one is the method where the irradiating time is controled by considering the current displacement of the actuator, the current velocity and a threshold relating to them. The other is a predicition control where the irradiating time is predicted by cunsidering the current displacement and the time lag of the optical shutter. It is clarified by the experiment that the prediction control is most applicable among these three methods.It can be said from these results that the optical actuator using PLZT element is applicable to the optical servosystem if they will be investigated further in detail. Less