The Study Of Feedback Control And Actuator System For Laser Beam Drift

In order to satisfy the requirements of the high precision in ultra precision manufacturing and testing field, more and more studies focused on improving the linear reference precision. Because of many advantages such as high brightness, good directivity, and good coherence etc, the laser beam has been widely used as the linear reference. But the drift of the laser beam restricts its applications required for higher precision.Aiming at improving the laser collimation precision, the characteristics of the piezoceramics actuator technique and flexible hinge driven technique have been analized in this paper. Based on these characteristics, a nano-precision laser beam drift feedback control and actuator system with high frequency response is designed to avoid the drift of the laser beam. The main researches on this topic include following steps:1. According to the working characteristics of the piezoceramics actuator, a piezo driven supply power based on the DC amplifying mode electric circuit is designed. A new style charging-uncharging circuit is used to expand power's frequency response, and to enhance its driven capability; After researching the factors that influence the power's static precision, the process of charging-uncharging, and the capability, the constant-current source is used in the power design to improve the load characteristics in various output. The method used in the power design improves the static capability and dynamic capability.2. Corresponding the J. M. PAROS classical structure model with the simplification expressions, an orthogonal two-dimensional micro-displacement stage is designed using the flexible hinge structure. Simulating the stage's model by the finite element analysis, exact mechanics model can be obtained, which could be used to improve the flexible hinge structure parameter in the real stage design.3. In the paper, the nonlinear hysteresis phenomenon of the feedback control and actuator system are analized theoretically. The flex mechanism of the piezoceramics actuator will cause the nonlinear hysteresis phenomenon. By using the Preisach model, the nonlinear hysteresis of the micro-displacement stage driven by the piezoceramics actuator can be modified .At last, the ripple, the stability, the resolution and the frequency response are tested by the various experiments. The frequency response of the power is 1.4KHz. The ripple is down to 6mV, and the resolution is 14mV. So the power's influence on the precision of the output displacement is nearly 0.14nm. At the same time, the flexible hinge micro-displacement stage, the static and dynamic capability of the laser beam drift feedback control and actuator system are tested through the experiments. Experimental results shows that the precision of the system the open-loop control is nearly 20nm.