The Key Technologies Of Autocollimation System Based On The Beam-Splitting Target Detecting Feedback Of Laser Beam Shift

With the rapid development of the ultra-precision manufacturing, microelec- tronics, micro-optics, micro-mechanical integrated manufacturing technology and space exploration, higher requirements on the measuring accuracy and stability of ultra-precision small-angle measuring table become more and more stringent. Traditional photoelectric autocollimators can only satisfy the common accuracy of small-angle measurements. But it is difficult to improve the accuracy in ultra-precision measurement for the influence of laser beam shift caused by laser thermal distortion, air disturbance, etc. Therefore, it is stringent to research and development an ultra-precision laser CCD autocollimation measuring system with high measurement accuracy and stability.In the subject The Key Technologies of Autocollimation System Based on the Beam-Splitting Target Detecting Feedback of Laser Beam shift, a method of ultra-precision laser CCD autocollimation technique for small-angle measure- ment is researched. The theoretics, methods and key technologies concerning are expounded in detail as following sections:Firstly, the dissertation makes theoretical analysis of the reasons cause laser beam shift, furthermore, the internal relations among these drifts and their influences on laser autocollimation measurement. Based on this, a new laser CCD small angle measurement method based on closed-loop feedback control techniques is proposed. A novel Beam-splitting Target Detector is designed to realize the separation of laser beam shift from measuring beam, and to achieve higher stability and accuracy applying closed-loop feedback control techniques.We study on the autocollimation optical measurement system, the beam-splitting target detector, the beam shift detecting device, the flexible micro rotating worktable, the closed-loop feedback control system made up of a PZT actuator and a micro rotating worktable and then, an photoelectric detect circuit with a four quadrants photoelectric detector is designed for real-time monitoring of the beam drift; complete parameter design and development of a flexible hinge to realize the conversion from the displacement of piezoelectric ceramic to angular change of the flexible hinge; get PID parameters by system identification and parameter setting; complete software design of the autocollimation system under the Visual C++ environment, which includes photoelectric signal acquisition and DAC module, piezoelectric ceramic driver program and PID control algorithm, etc..Experiment for the performance of each main component of this system is performed and researched. We test and analyze the static stability under various voltages, the voltage resolution, the output linear characteristics of the PZT driving power and the nonlinear of the flexible micro rotating worktable. We also make contrastive experiments for the measuring stability, resolution and uncertainty using the dual-frequency laser interferometer. And lastly, we analyze and research the measuring errors of the system. In the end, we also analyze every error source for the system.The experiment results indicated that the stability has improved from 0.23″to 0.14″, and the accuracy has improved from 0.24″to 0.16″since the applying of the closed-loop feedback control, which fully verify the correctness and effectiveness of this approach.