The Research For Technology Of High Precise Laser Facula Position Detection Based On The Quadrant Detector

Laser measurement technology plays a significant role in modern science and technology, especially the technology based on detection of laser spot position. Benefitting of its high measurement precision and preferable anti-noise ability, this method is widely used in high-precision position detection of a static target and dynamic object tracking, such as, multi-degree of freedom of the target position and angle measurement, optical tweezers, laser semi-active guidance and space laser communications. A high-performance photo electric position detector is important in the spot position detection system. Four-quadrant detector(QD) has high sensitivity and faster response speed, and it is more frequently utilized in the laser spot position detection system. Therefore, laser spot position detection methods and the influence of noise on the position detection accuracy in QD-based laser spot position detection system were investigated in this thesis. The contributions of this work are summarized as follows:(1) Firstly, the mathematical model of a QD-based spot position detection system is built, which is basis of analyzing spot position detection principle of QD. Then how used to evaluate the spot position detection performance is analyzed, and the major factors affecting the spot position detection precision is also analyzed.(2) Two fitting algorithms were proposed based on the analysis and comparison of several commonly used spot position detection algorithms:(a) By introducing error compensation factor and taking into account the effect of detector radius and gap width, an Infinite integral fitting algorithm was proposed.Compared with the original algorithm, this algorithm could improve the detection accuracy of the spot position greatly and there is only one parameter used for fitting.(b) By analyzing the error characteristics of the fitting algorithm of Infinite integral, a new Composite fitting algorithm was proposed by innovatively introducing a new error compensation function-Boltzmann Mathematical Functions. This algorithm could greatly improve the detection accuracy of the spot position and have reached the sub-μm detection accuracy in the larger detection range.(3) Effect of noise on the position detection accuracy was investigated. Mathematical models of the spot position standard deviation and spot position error under some probability conditions were introduced. The dependence of the spot position detection accuracy on the spot radius, spot centroid and the SNR are analyzed;(4) Designing the amplifier circuit and four synchronous AD data acquisition system. The spot position detection accuracy based on Infinite integral fitting and Composite fitting algorithms were verified based on a displacement test platform. The correctness of the spot position standard deviation model and spot position error model under some probability conditions were also verified.