Key Engineering Materials Vol. 552

Abstract: Optical correlation technology is an important application in target recognition field, which can apply Joint Transform Correlator (JTC) to achieve target recognition. For the Low Light Level (LLL) target with low contrast and background noise interference, using optical correlation method may reduce the recognition ratio. In order to solve the problem, an effective algorithm-adaptive directional lifting based on wavelet transform (ADL) is used to process LLL target image. LLL image enhancement and target edge extraction are applied in this algorithm. Experimental results show that this algorithm can enhance the brightness of the correlation peaks and has the advantage of quick operation.

Abstract: Moving target recognition has a wide application in varieties of domains and has received more attention in recent years. Among all the recognition methods, optical correlation technology, using hybrid optoelectronic joint transform correlator (HOJTC), has the merits of parallel, large capacity and high-speed, so it is considered as one of the most effective methods for moving target detection. But in the course of detecting, some targets are too small to be recognized by HOJTC. These small targets in cluttered background and strong noise may affect the brightness of the correlation peaks and have a serious influence on target recognition results. In order to solve this problem, this paper applies a wavelet multi-scale edge fusion algorithm which firstly extracts the edge at different scales by wavelet modulus maximum method, and then fuses the detected edge to obtain more edge information of the target. In addition, for the moving distortion problems, taking temporal state of the target as the template can achieve the template update. To prove this method, many detection experiments of small moving targets have been performed with optical correlation method. As an example a small target “boat” taking up only pixels is presented. The recognition results show that the brightness of the correlation peaks is enhanced and the target recognition ratio is increased. The conclusion can be drawn that applying this algorithm in optical correlation method can realize the small moving target recognition successfully and expand the application to scope of optical correlation technology.

Abstract: In order to design a moving target fast tracking system with respect to a real-time and stable tracking process, especially when the shape of moving target or its environment condition changes, a new algorithm named SURF-KMs is proposed. SURF-KMs combines the advantages of SURF algorithm with a cluster analysis of K-means method. First, feature points are collected and then they generate the matching template vectors based on the SURF algorithm. Second, the feature points and the center of the target are estimated by using the K-means method to determine the target’s cluster scope and update the tracking window. Finally, a self-adapting updating strategy for matching template is also proposed in order to track moving target automatically. Experimental results indicate that SURF-KMs is mostly able to achieve a stable tracking while with the monitored target rotating, scale changing, and also the environment illumination glittering. Moreover, it can satisfy the system requirements of tracking stability, higher precision and anti-jamming.

Abstract: Along with the rapid development of science and technology, and due to the special advantage of laser communication, such as big traffic and good secrecy, the application of optical communication is more and more wide. One of key technologies is the structure design of receiving system. In this paper, a structure of receiving system for optical communication based on Cassegrain system is introduced. Consist of the support structure of primary mirror and secondary mirror, adjustment structure of secondary mirror, structure design of reflectors, etc. FEM is used to analyze the distortion of primary mirror which is based on this structure. The distortion is caused by pressure, self-weight and temperature change, etc. And the stress deformation of primary mirror tube is analysed particularly. Analysis and test results demonstrate that the design project is reasonable.

Abstract: According to the microstructure characteristics of the optical components surface, the paper designs a bridge right-angle flexure hinge driven by a piezoelectric ceramic. It meets the driving micro-displacement magnification requirements and solves the coupling problem in work. Using the calculation formulas of statics and calculation formula of bending moment, the thesis explores the motion law of piezoelectric ceramics with 1KHZ excitation frequency. Through the exploration of the factors of bridge flexure hinge angle stiffness and tensile stiffness, the mathematical model of input displacement and output displacement is established. Studying the theory about the elimination of motion process coupling, it excavates the function relationships of flexure hinge angle and magnification. And the relationship is unearthed among driving force of piezoelectric ceramic, the flexure hinge stiffness, cutting force and mass of cutter system. The paper establishes their mathematical model between the above elements and the output micro-displacement, and the theoretical result is calculated by Matlab. Finally, using Pro/Engineer 3D digital modeling and analysis of simulation results by Ansys, it is found that the error can be controlled in an acceptable range by comparing the theoretical results with simulation results. Through the above analysis, the theoretical design is found to be reliable and effective.

Abstract: The result of target recognition is always influenced by the clutter background, low contrast and deficiency luminance of image. Besides the factors mentioned above, detection and recognition of partial masked target has the character of fragmented target, which leads to another problem. All the harmful factors cause that target recognition can not be realized by hybrid optoelectronic joint transform correlator (HOJTC) due to the weak correlation peaks, even no peaks appear. In this paper, input image of HOJTC is processed by the method of adaptive threshold, and power spectrum is processed by wavelet transform (WT) as well. The combination effectively controls the disturbance of noise and enhances the energy of diffractive light of target. Experiment of HOJTC shows that the method can enhance the contrast of correlation peaks of partial masked target and improve the detection and recognition capacity of HOJTC. As an example, the experiment results of fragmented airplane target before and after processing are shown in the paper, which demonstrate the effectiveness of the method.

Abstract: Rolling Imprint Lithography is an Enabling Technique for the Mass Production of Ultra-Precision Micro-Structured Surfaces which are Widely Used in High Value Added Optical Products such as Backlight Guides for Display Devices. the Accuracy of the Produced Micro-Structured Surfaces Relies Heavily on the Master Roller of which Quality is Difficult to be Controlled by Traditional Off-Line Measurement Process due to the Large Dimension and Heavy Weight of the Workpiece. this Paper Presents a CCD Based Non-Contact Measurement System to Perform the on-Machine Measurement of the Structure Pattern on Machined Rollers. Instead of Measuring each Single Structure on the Roller, the System is more Focused on the Characterization of the Conformance of the Structure Pattern with the Designer’s Requirement. Low Angle Monochromatic Light is Used to Extract the Structure Pattern on the Machined Roller Using a High Magnification Objective Lens with a High Resolution CCD Sensor. the Image Processing Techniques are then Employed to Characterize the Captured Image Based on the Designed Pattern Structure. the Developed System has been Mounted on a Single-Point Diamond Turning Machine to Measure the Machined Structured Roller, and the Results Indicate that the Developed Measurement System is Able to Perform the on-Machine Measurement and Characterization of the Structure Pattern of the Machined Roller with Sub-Micrometre Accuracy.

Abstract: Plasticfilms with Embossed Micro-Structured Patterns have been Widely Used Inbacklight Guide Panels. the Mass Production of these Films Demands Forultra-Precision Roller Embossing of Micro-Structured Patterns on Plastic Filmsby Precision Pattern Rollers. due to the Heavy Workload and High Precisionrequirements, Ultra-Precision Rollers with Microstructures are very Difficultto be Machined in the Level of Submicrometer Form Accuracy and Surface Finishin Nanometer Range. this Paper Presents Theoretical and Experimental Studies Ofultra-Precision Machining of Precision Rollers with Microstructures. Themachining Mechanism for Precision Roller is Firstly Explained, and Hence Astudy of Effect of Cutting Strategies on Surface Generation in Ultra-Precisionmachining of Micro-Structured Pattern Rollers is Presented. this Includes Thestudy of Different Cutting Trajectories, Length-to-Diameter Ratio of Therollers, Mounting Method for the Rollers, the Number of Cuts in the Formationof the Micro-Structured Patterns, as well as the Time Budgeting for Adoptingdifferent Cutting Trajectories in Ultra-Precision Machining of Micro-Structuredpattern Rollers. the Results of the Study Provide an Important Means Forenhancing the Surface Quality and Optimizing the Time for Machining Precisionrollers.