| Beam pointing control system is an important part of current laser medical,laser processing,laser communication,and other fields.With the continuous development of optical systems,various dynamic interference problems have been plaguing the pointing accuracy of optical systems.At present,Europe and the United States,and other countries have more mature beam pointing control products,domestic research in this area started late,independent research and development of the product compared to the existence of too large,low precision,highcost drawbacks.Therefore,it is important to develop and design a high-precision,low-cost,and highly integrated autonomous controllable beam pointing system.This thesis clarifies the current necessity of beam pointing control in many fields with the demand for laser technology applications as the research background.After a comprehensive analysis of domestic and international research work on beam pointing control technology and the current products on the market,this system uses the fast steering mirror compensation method as the basic research method.The fast steering mirror-based photoelectric integration system is designed and implemented,and the feasibility of the beam pointing system is finally demonstrated through experiments.The specific study of this thesis is as follows:1.The study establishes the optical path system and the system-based communication design.On the one hand,the modeling is done for the way the beam deflection behavior occurs;on the other hand,the optical path system with double fast steering mirrors is proposed for the lack of degrees of freedom of single fast steering mirror.The optimized optical path system increases the device utilization,reduces the system size,and compensates for the large size of the system.The communication design of the system is carried out to improve for the actual system.2.The signal feedback control system is studied and designed.The voltage acquisition circuit and control output circuit are designed for the Ⅰ-Ⅴ conversion and amplification of the weak photocurrent output from the position sensitive detector.The software design then implements the position information acquisition and output as well as the PID feedback algorithm.3.Analyze the errors generated by the position sensitive detector and propose solutions.A combination of hardware and software is used to analyze and remove the background light,dark current,circuit noise,and dynamic response errors that occur in the system in conjunction with the actual situation.A polynomial fitting method is proposed for the nonlinear errors generated by the position sensitive detector because of the inhomogeneous resistance.By collecting data points,the collected points are fitted to the actual position points.4.Build the optical path system and perform experimental verification.A control experiment is first designed to test the effect of the laser spot and optical power on the experiment.For the system simulation experiments,interference and delay are added to simulate the coefficients to prevent the overshoot phenomenon.Experimental verification is performed for the single fast steering mirror system to confirm the limitations of the single fast steering mirror system.To be close to the actual application and verify that beam pointing can be achieved at different positions,the photosensitive surface is placed in each of the four quadrants with the whole system loaded with vibration,and the final results show that the system can stabilize the pointing offset range within 13 μrad and complete the beam pointing control. |
