To compensate for disturbances in an aircraft’s forward flight and variations in its attitude and angular velocity in the imaging process of photoelectric imaging system, a method of image motion compensation using a fast steering mirror was put forward. First, the working sequence of the image motion compensation system was designed. The position of the fast steering mirror is established by increasing the oblique wave to allow the fast steering mirror to move at the desired speed and compensate for the image motion speed. Then, a mathematical model of the fast steering mirror was established. A linear extended-state observer is designed to estimate the disturbance in real-time, and disturbance compensation is generated to offset the disturbance. Finally, a step response experiment and a tracking experiment were performed to test the characteristics. The step response curve shows that the system’s stable time is 1.8 ms. The tracking characteristic is determined by a given scan curve. The fast steering mirror can satisfy the requirement for a high-speed and highly precise tracking system. It improves the system’s interference rejection performance and reduces the difficulty of controller design.
Affected by voltage quantification, manufacture technology and environment temperature, the actual deflection accuracy and diffraction efficiency of liquid crystal optical phased arrays (LC-OPA) are in error with the ideal situation when the beam deflected. In this paper, we studied the method of improving the deflection performance of LC-OPA based on stochastic parallel gradient descent (SPGD) algorithm, and choose Strehl ratio (SR) as the performance evaluation function for simulation experiments. We analyzed the influence of the disturbance amplitude δ, the gain coefficient γ and the number of periodic electrodes N on the performance optimization of the SPGD algorithm in the LC- OPA beam. Draw the conclusion: When the number of periodic electrodes N is within a certain range, appropriate adjustment of the disturbance amplitude δ and the gain coefficient γ can achieve better optimization effects, and the larger the deflection angle, the better the optimization effect. When the number of periodic electrodes N is 4, the amplitude of disturbance δ is 0.0009, and the gain coefficient γ is 0.1, the ideal optimization effect of SR of 0.82 can be achieved, which provides a theoretical basis for improving the large-angle deflection precision and diffraction efficiency of LC-OPA.
Based on the processing mechanism of double-sided polishing machine and working mode, conducted intensive research, found that the motion state of the disc and pads can be simplified as a workpiece relative motion, and a complete mathematical model is built for the motion state of any point on the polishing disc. In view of the relationship among the workpiece’s motion characteristics, polishing process parameters and polishing effect, the computer is used to simulate the motion of the polishing disc relative to the workpiece in the state of steady motion. Taking the motion parameters as the control factor, by changing the ratio of different parameters, the different trajectory of the workpiece’s relative motion is obtained, and the regular pattern of the value of each factor on the motion trajectory distribution is explored. Finally, a set of parameters with the best grinding track uniformity and polishing effect were obtained through analysis and summary.
To improve the control accuracy of optoelectronic imaging equipment, the factors that affect the accuracy of the optoelectronic axis pointing are analyzed. Following Snell’s law, the kinematic coupling equation of the line-of-sight (LOS) angle based on the fast steering mirror (FSM) is established. The calibration method of the FSM system is designed according to the obtained motion characteristics, and a nonlinear correction method is designed to decouple the LOS equation. For a two-axis fast mirror with a stroke of ±20 mrad, the LOS pointing error is <1 μrad when the incident angle is 45 deg, which equates to an improvement of at least 78.9 times compared with linear correction methods. The nonlinear correction method is verified by practical experiments. The method provides a theoretical basis for generating position instructions and thus enables a precise FSM-based pointing system.
Beam steering is an important part of achieving target searching, aiming, tracking, capturing and imaging. It has important applications in the fields of new system laser radar and space laser communication. In this paper, the basic principle of optical phased array (OPA) beam steering is detailed, the development status and research results of OPA beam steering technology based on liquid crystal, optical waveguide and MEMS are introduced, and the application of OPA beam steering technology is briefly described. Finally, the prospect of optical phased array beam steering technology is prospected.
In the ion beam figuring(IBF) process, a stable removal function is the premise of ion beam figuring, and the information of removal function is generally obtained by experimental methods. Based on the study of removal function model, the stability of the removal function is analyzed by line scan method. A line scan experiment was performed on a 50mm diameter optical component, within 1h, the removal function's peak removal rate varies in 0.74%, full width at half maximum (FWHM) varies in 0.41%, and volume removal rate varies in 2.62%. The removal function is stable and can be used for actual ion beam figuring. Using this method, the stability of the removal function can be verified to ensure that it satisfies the figuring requirements.
Pneumatic loading system is an important part of the control system of double-sided polishing machine. It realizes ultra-precision polishing of work piece by accurately controlling the pressure of the upper polishing disc loaded on the upper surface of the work piece. Pneumatic loading system is a typical nonlinear, time-varying system. The traditional PID control parameter setting is very complex, and it is difficult to meet the control requirements. In order to accurately control the parameters of the PID control, this paper will join the fuzzy control block in front of the PID control, make error and error change rate as input of fuzzy control, and PID control parameter as output, according to the selected membership functions and fuzzy rules correction the PID control parameters in real time, constitute adaptive fuzzy PID control. This control strategy can effectively control the pneumatic loading system, with strong stability and robustness. To achieve the stable control of polishing pressure, satisfy the accuracy requirements of medium and large diameter double-sided polishing machine.
Aiming at the effect of converge laser light scattering caused by subsurface micro-defect, and the change rule of laser scattering modulation was studied. First, the geometry model is built by defect type; then, by finite element method based on electromagnetic theory, the scattering light intensity distribution and variation curve with different detection defect depth, which convergence light spot focus on, were researched by numerical simulation. Finally, simulation model was verified by comparing experiment. This research results are important to setup the mathematical relation between subsurface defect and light scattering, and realize quantitative detection for the subsurface defect of optical element.
Coherence Holography is an unconventional holography technique, where a computer generated hologram is illuminated by spatially incoherent light and the recorded object is reconstructed by the 3D distribution of a spatial coherence function. Because of its unique capability of controlling and synthesizing spatial coherence of quasi-monochromatic optical fields in 3D space, coherence holography has been applied for spatial coherence tomography, profilometry, and the generation of coherence vortices. In this paper, we experimentally demonstrate three particular spatial coherence functions by using coherence holography, and study the propagation characteristic of the coherence functions.
This paper proposes that surface roughness of optical element is detected using total integrated scattering method, Meanwhile, establishing the relational model between surface roughness and subsurface damage to get the depth of subsurface damage rapidly and accurately after we measured surface roughness so as to achieve the goal of detection of optical element’s surface microstructure.
Proc. SPIE. 9297, International Symposium on Optoelectronic Technology and Application 2014: Laser and Optical Measurement Technology; and Fiber Optic Sensors
Guidance precision is the key indexes of the guided weapon shooting. The factors of guidance precision including: information processing precision, control system accuracy, laser irradiation accuracy and so on. The laser irradiation precision is an important factor. This paper aimed at the demand of the precision test of laser irradiator,and developed the laser precision test system. The system consists of modified cassegrain system, the wide range CCD camera, tracking turntable and industrial PC, and makes visible light and near infrared target imaging at the same time with a Near IR camera. Through the analysis of the design results, when it exposures the target of 1000 meters that the system measurement precision is43mm, fully meet the needs of the laser precision test.
Proc. SPIE. 9297, International Symposium on Optoelectronic Technology and Application 2014: Laser and Optical Measurement Technology; and Fiber Optic Sensors
Dynamic feature of Weapon equipments is one of important performance index for evaluating the performance of the whole weapon system. The construction of target range in our country in fire control dynamic testing is relatively backward; therefore, it has greatly influenced the evaluation on the fire control system. In order to solve this problem, it's urgent to develop a new testing instrument so as to adjust to the armament research process and promote weapon system working more efficiently and thereby meeting the needs of modernization in national defense. This paper proposes a new measure which is used to test the stability precision of the fire control system, and it is installed on the moving base. Using the method, we develop a testing system which can test the stability precision of the fire control system and achieve a high precision results after testing. The innovation of the system is we can receive the image not only by CCD, but our eyes. It also adopts digital image-forming and image processing technique for real-time measurement and storing of the target information; it simultaneously adopts the method adjusting the platform and the corresponding fixture mounted on a sample to measure the stable precision and the precision of corner of stabilizator. In this paper, we make a description on the construction of the system and the idea of the designing of the optical system. Finally, we introduce the actual application of the system and testing results.
Give the figures, which describe the relation between Ion Beam Figuring parameters(Ion beam density, energy, incident angle) and removal features based on SRIM software, the beam removal function model is built and proposed an algorithm of dwell time using RBF neural network optical controlling removal function and processing route. Then, Analyzed the error of algorithm and did some related compensation researches. Results showed that under a certain accuracy, the proposed algorithm can greatly speed up, control more optimization, make the IBF technology more practical, promoting the further development of the super precision optical surface processing technology.
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