Optics Design and Precision Manufacturing Technologies

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Authors: Shuo Jen Lee, J.J. Lai, Yu Ming Lee, Chi Yuan Lee, K.T. Yang, C.W. Peng
Abstract: In this study, the parametric effects of the EMM process were studied by both numerical simulation and experimental tests. The numerical simulation was performed using commercial software, FEMLAB, to establish a multi-physics model which consists of electrical field, convection and diffusion phenomena to simulate the parametric effects of pulse rate, pulse duty, electrode gap and inflow velocity. From the simulated results, the relationship between parameters and the distribution of metal removal could be established. Proper process variables were also chosen to conduct the EMM experiments. After the experiments, the profile of the processed rectangular slot was measured by a Keyence digital microscope. Comparing profile of the processed rectangular slot with the profile of the cathode, the machining accuracy of EMM process could be determined. It could also verify the efficacy of the multi-physics model for predicting machining accuracy. From this study, the effects of parameters such as pulse rate, pulse duty, electrode gap and inflow velocity are better understood. The simulation model could be employed as a predictive tool to provide optimal parameters for better machining accuracy and process stability of the EMM process.
Authors: Woo Sik Yoo, Quan Qia Jin, Dong Sam Park, Eun Je Seong, Jin Yong Han
Abstract: Powder blasting is similar to sand blasting and effectively removes hard and brittle materials. With an increase in the need for machining of ceramics, semiconductors, electronic devices and LCDs, micro abrasive jet machining has become a useful technique for micro-machining. In this study, we first investigated the effects of the blasted glass surface’s characteristics and shape under different blasting parameters; second, we examined the predictive models for material removal and surface roughness that have been developed in terms of blasting pressure, scanning speed and abrasive flow, using response surface methodology by experimental data. The established equation shows that the blasting pressure was the main factor influencing the material removal and surface roughness. In addition, analysis of variance for the firstorder model of material removal and surface roughness shows that the coefficient of determination (R2) is 99% and 98%, respectively. The associated p-value for the two models was lower than 0.01, indicating that the models are statistically significant.
Authors: Zhen Long Wang, Bao Guo Zhu, Wei Liang Zeng, Li Zhong Sun
Abstract: There are many influence factors of electrochemical micromachining (EMM) development. So the characteristics of EMM technology were analyzed firstly. It was an effective method that the nanosecond pulses voltage was used in EMM, and the nanosecond pulses voltage was prepared to solve the problems of machining area, using small gap, and machining micro 3D structure. Its minimum pulse duration is 5ns, and its voltage, current, and duty ratio can be changed freely. Moreover, many experiments of EMM were carried into execution. After the phenomenon and results of the experiments were analyzed, the reformative project of experiment was put forward. The feasibility of the project and technique route was testified correctly by the nanosecond pulses voltage on the multifunction machine tool which was manufactured independently. After studying on the influences of EMM technology, the experiences of EMM process will be enriched and make EMM have a further development.
Authors: Bo Zhao, Jing Lin Tong, Yan Wu, Guo Fu Gao
Abstract: Using TEM, SEM and XRD, the surface microstructures of nanocomposite ceramics prepared by heterocoagulation was studied in two-dimensional ultraprecision grinding with ultrasonic assistance. This research was focused on the structure of ground surface degenerating layer, surface generation mechanism and characteristics of nanocomposite ceramic parts. The experimental results showed that the microscopic deformation mechanism of the ordinary Al2O3 parts was grain- boundary twinning and grain-boundary sliding while microscopic deformation mechanism of nanophase ceramic parts was the inner crystal dislocation of strengthened phase with intragranular structure. And its deformation coordination mechanisms were the grain-boundary sliding and coordination deformation of intercrystalline second-phase. The observation on the fracture surfaces of nanocomposite materials with different microscopic structures by TEM and SEM showed that ZrO2 particles had an important effect on the generation and expansion of crack in ceramic parts. The introduction of ZrO2 particles strengthened the interface intensity of grain boundary. If there were rich ZrO2 particles on the grain boundary, the cracks generated during the grinding process would be prevented. Smooth and plastic deformation processing surface was obtained. It was proved further that the nanophase materials behaved transcrystalline fracture due to the nano particles, dispersed in the grain boundary and prevented the expansion of crack. This material’s fracture behavior made favorable surface possible. In the precise grinding of nano materials, the plastic removal mechanism dominated the process. The dislocated depth of the nanocomposite ceramics after grinding was bigger than that of common ceramics, which meant that dislocation increased.
Authors: Juan Yu, Qiu Sheng Yan, Jia Bin Lu, Wei Qiang Gao
Abstract: Based on the magnetorheological (MR) effect of abrasive slurry, the particle-dispersed MR fluid is used as a special instantaneous bond to cohere abrasive particles and magnetic particles so as to form a dynamic, flexible tiny-grinding wheel to polish optical glass, ceramic and other brittle materials of millimeter or sub-millimeter scale with a high efficiency. Experiments were conducted to reveal the effects of different process parameters, such as grain sizes of abrasive particles, machining time, machining gap between the workpiece and the rotation tool, and rotation speed of the tool, on material removal rate of glass surface. The results indicate the following conclusions: material removal rate increases when the grain size of abrasives is similar to that of magnetic particles; machining time is directly proportional to material removal, but inversely proportional to material removal rate; machining gap is inversely proportional to material removal; polishing speed has both positive and negative influence on material removal rate, and greater material removal rate can be obtained at a certain rotation speed. In addition, the difference of the machining characteristics between this new method and the traditional fixed-abrasive machining method is analyzed.
Authors: Feng Zhou Fang, Yu Chan Liu, Qing Xiang Pei, Xiao Tang Hu
Abstract: A new method on examining the micro cracks of monocrystalline silicon during nano indentation is proposed. It is established based on a study of the increasing rate of absorbed energy in nano indentation. This method provides a simple approach in understanding whether cracks on the silicon surfaces occur, while it is tedious in conventional method.
Authors: Hong Gue Shin, Heon Young Kim, Byeong Hee Kim
Abstract: Nano hot or thermal embossing has many advantages of comparatively few process steps, simple operation, relatively low tooling cost and high replication accuracy for small features. However, because of its long processing time, it has been known as being less competitive than nano injection molding. In order to overcome the weakness of long processing time, the high speed nano hot embossing system has been developed and its characteristics were investigated. Nanopatterned stampers made of Ni and Si were fabricated by the laser mastering and electroforming process and the DRIE and LPCVD or thermal oxidation process respectively. In order to make the processing time shorter and get relatively higher aspect ratio nano/micro features, especially, the temperatures of the molds were controlled actively and precisely during the embossing process. Through various experiments, nano embossing parameters, such as temperature, pressure and processing time, are optimized and the high aspect ratio nano features could be obtained.
Authors: Rong Yuan Jou
Abstract: A nano-porous silicon film deposited on a flexible cyclic olefin copolymers substrate is adopted to insulate the structure at high processing temperature during device manufacturing. In this study, the thermal conductivity of nano-porous silicon film modeled by Lysenko et al. [7] is implement to do the one-dimensional heat conduction analysis and to calculate the temperatures theoretically and numerically. In numerical work, the COMSOL finite-element based package is used for the numerical computations and effects of applied temperature loading, thickness of nanoporous silicon layer, and porosity are discussed. As shown in the analysis results, thickness of 200μm has the lowest temperature than other thicknesses, 25μm, 50μm, and 100μm, etc. Porosity plays a vital effect for thermal insulation. From the analyses, the case of 80% porosity has the larger temperature decrement than cases of 40% and 60%. It may be attributed to the lower conduction by higher porosity. Also, these temperatures show good agreement between the theoretical and numerical results and are consistent to the Lysenko et al. [7] statement for nano-porous silicon film for thermal insulating material.
Authors: Ching Song Jwo, Chien Chih Chen, Ho Chang, Sih Li Chen, Shin Jr Ho
Abstract: This study develops a measurement method for testing the efficiency of photocatalysts in the degradation of NH3 gaseous concentrations. The catalysts used in this study are the same as those used previously in our UV/VIS spectrophotometer. Reaction measurements were carried out at 27°C and 17°C under ambient pressure on Heat Ventilating and Air Conditioning (HVAC) system. Quartz plates were coated with TiO2 nanocatalyst. Then the plate was put in the stable reaction cell under different flow rates of circulation. The experiment gives a direct and simple measurement of ammonia flux and hence of overall ammonia emission rate. The results reveal that the Submerged Arc Nanoparticle Synthesis System (SANSS) TiO2 nanocatalyst has excellent degradation efficiency towards NH3, so that when it is exposed to UV irradiation for 60 minutes, the gaseous concentration can be reduced to 10% of the original concentration. In addition, the rate constant of the degradation reaction of the self-made TiO2 nanocatalyst towards NH3 is as high as 0.039min-1.
Authors: Shih Miao Huang, Jui Chang Lin
Abstract: Optically, humans can discriminate between colors as close as 2nm in wavelength in relative judgment task. However, there is little research to discuss color differences for absolute color judgments in which the comparison is held in memory. Therefore, the intent of this study was to explore effects of wavelengths on the Just Noticeable Difference (JND) of absolute judgments in our perceptual world. A color identification task was utilized to investigate the JND of wavelengths. In the experiment, the Standard Stimulus Color (SSC) and the Comparison Stimulus Color (CSC) were successively presented. The SSC which was presented first must be stored in working memory and recalled when the second color, CSC, is presented. Subjects had to decide if the CSC matched the SSC. Each CSC was presented four times for each subject in the experiment. The CSC wavelength that was recognized as different from the SSC twice was designed as a JND wavelength. Five SSC wavelengths with 100% saturation and 100% lightness were chosen from the hue circle of HLS color space which included 360 hues. Because the hue circle is a circle, the CSC may be on both sides of a SSC in the hue circle. The CSC hue which may be located on the clockwise direction or counter clockwise direction of the SSC was called clockwise direction color (CD) or counter clockwise direction color (CCD), respectively. The wavelengths expressed with HLS color space were translated into coordination of CIE1931 (x, y)-chromaticity diagram. The results indicated that threshold sensitivities varied for different wavelengths on absolute judgment tasks. The lights with longest or shortest wavelength had greater JNDs than ones with middle wavelengths for absolute judgment tasks. The comparison of the results of the experiment on absolute color judgment tasks and MacAdam’s (1942) findings for relative color judgment tasks were also discussed.

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