Key Engineering Materials Vol. 552

Abstract: The micro-lens array for CCD systems can enhance the utilization efficiency of light energy, then improve its detection sensitivity. This paper firstly researches on the principle of micro-lens array for CCD integration, the lens changing refractive index theory and the mechanism of ionic exchange on glass materials. Then, with reasonable design of the mask and optimization the ionic exchange process parameters, the paper finally produces the Rectangular Plane Arched Shape (RPAS) micro-lens array on the plate glasswith the unit feature size being 22μm x 22μm. The results show that the RPAS micro-lens array’s fill factors could be achieved 93%, and the spectral sensitivity can be improved by 0.3 times. The mask plays a decisive role in micro-lens which is manufactured by ionic exchanged method. The reasonable selection of the mask parameter can eliminate the void that in the circular aperture planar micro-lens array, and enhance the fill factor; in the ionic exchange process, it is easy to obtain the large refractive index by using the ion-pair that have big differences. The ionic exchanged temperature below the glass softening temperature at about 20°C is appropriate.

Abstract: For precise geometrical design and wear-resisting design of the roof diamond tool for ruling echelle grating of large area, computer aided reverse design was used to solve the problems. Firstly, based on the mechanical parameters of grating， Al film got from the nanoindentation test and nanoindenting simulated analysis. The optimized geometrical parameters of the roof diamond tool are got with an orthogonal analysis in a dynamical finite element model of simulating mechanical ruling. Then an equivalent resistance design method is put forward to improve the wearable ability of the roof diamond cutter with wear simulated analysis. Finally, a roof diamond tool of trial-lapping is presented for grating ruling investigation to verify the design effect.

Abstract: Micro-channel Plate (MCP) with Ion Barrier Film(IBF) is one of the main technical indicators that restrict the performance of the third generations of Low Light Level Image Intensifier(LLLII). IBF with inferior quality can be a direct impact on the performance of the third generations of LLLII or even makes it not work, and it’s very unfavorable in the tube mass production and promotion. In response to this urgent requirement, in order to improve the quality and preparation of the finished product of the Al2O3 on the input side of MCP prepared by magnetron sputtering, the paper carries out the process optimization of magnetron sputtering used for image intensifier. By simulation of Ar ion bombarding Al2O3 target, while under the guidance of the working principles of the magnetron sputtering and thin film growth theory, we change the working pressure、 sputtering power、 argon flow and other process parameters by using magnetron sputtering machine developed in China, to change the coating deposition rate of Al2O3, and to increase the lateral migration of the film-forming process of Al2O3. Finally we prepare a uniform、 continuous and compact Al2O3 Ion Barrier Film. At last the optimal technique is obtained: Sputtering pressure is 2.6×10-1Pa, Ar2 flux is 90sccm, sputtering power is 170W, and the thickness of film is 80Å. We test the performance of MCP with optimized films by using the MCP performance testing devices, contrasting with pre-fabricated thin-film quality, and the results show that the average gain decline is dropped, the dead volt is lower, and the quality of the films prepared by this process is significantly better, yield and view pass rate is as high as 90%, meeting the dual demands of high electronic transmittance and high ion blocking rate of IBF.

Abstract: In Generation III image intensifier tubes, the input of the microchannel plate is typically coated with a thin Al2O3 film to prevent ions penetrating and damaging the delicate Cs-O activation layer of GaAs cathode. While the application of an ion barrier film to the MCP greatly improves the mean time to failure of the image intensifier tube, it unfortunately produces electron scattering to cause a significant degradation in the Modulation Transfer Function and resolution of the image tubes. To obtain an overview of the role of the ion barrier in Generation III image intensifiers, in this paper, we present the results of a Monte Carlo simulation on scattering electron transport through Al2O3 film with various photocathode voltage, density, thickness, and stoichiometry. Using Monte Carlo simulation on scattering electron ways, we get the MTF curve of film at the accelerating voltage of 400v, a thickness of 10nm, and a density of 0.3 g/cm3. The simulation results play an important role on optimizing the quality and facture technique of ion barrier film.

Abstract: The technology of ultra-precision machining with single crystal diamond tool produces advanced components with higher dimensional accuracy and better surface quality. The cutting-induced heat results in high temperature and stress at the chip-tool and tool-workpiece interfaces therefore affects the materials and the cutting tool as well as the surface quality. In the ultra-precision machining of al6061, the cutting-induced heat generates precipitates on the machined surface and those precipitates induce imperfections on the machined surface. This paper uses the time-temperature-precipitation characteristics of aluminum alloy 6061 (al6061) to investigate the effect of feed rate on the cutting-induced heat generation in ultra-precision multi-axis milling process. The effect of feed rate and feed direction on the generation of precipitates and surface roughness in ultra-precision raster milling (UPRM) is studied. Experimental results show that heat generation in horizontal cutting is less than that in vertical cutting and a larger feed rate generates more heat on the machined workpiece. A smaller feed rate produces a better surface finish and under a larger feed rate, scratch marks are produced by the generated precipitates and increase surface roughness.

Abstract: Largely owing to the high cost of masks for lithography, recently there is a strong interest in maskless lithography. Maskless lithography is a potential program to overcome the high cost caused by rising price of the masks. Because of the advantages of low cost, high flexibility and short production cycle, digital mirror device (DMD)-based maskless lithography has been brought storm attention by people. Both the theory and experiment of DMD-based maskless lithography achieved good results. Maskless lithography systems based on DMD are analyzed in this review. Principles of construction, examples of implication, as well as future development direction are discussed.

Abstract: This paper describes a modeling method for film thickness variation within plasma enhanced chemical vapour deposition (PECVD) processes. The model enables the identification and optimization of deposition process sensitivities to electrode configuration, deposition system design and gas flow distribution. An comparison between theory and experiment is provided for PECVD of diamond-like-carbon (DLC) deposition onto flat and curved substrate geometries. This process utilizes butane reactive feedstock with an argon carrier gas. Radio-frequency plasma is used. The PECVD deposition system is based on co-planar 300mm diameter electrodes with separate RF power matching to each electrode. The system has capability to adjust the electrode separation as a parameter to optimize uniformity. Vacuum is achieved using dry pumps with real time control of butterfly valve position for active pressure control. Deposited film thickness sensitivities to electrode geometry, plasma power density, and pressure and gas flow distribution are demonstrated. In addition to film thickness uniformity, optical, durability and environmental performance of resulting DLC on germanium substrate materialreported.

Abstract: The structure of core shaft combined with mercury belt is widely used as the primary mirror supporting structure of 1 meter class and 2 meter class large aperture telescope currently. In order to reduce the structure jitter of primary mirror, the fitting clearance between core shaft and shaft sleeve is very small, so clamping stagnation occurs during installation and disassembling process of core shaft. The removal method of clamping stagnation of core shaft is introduced. Mechanical analysis of core shaft and primary mirror is applied to make sure that the primary mirror is safe. Some tools are designed specially, and the process and the attention points to remove core shaft are introduced. In this way, the clamping stagnation of core shaft can be removed easily. The core shaft of 1 m class primary mirror was removed by the method and the primary mirror was excellent without damage.

Abstract: Clitella magnetorheological finishing is a processing ultra-smooth surface method, which has high processing efficiency and relatively low precision machine tool mechanical structure. This paper introduced processing methods that use a clitella magnetorheological finishing technology to achieve an arbitrary radius of curvature of the spherical optical parts. The paper design the device and use this device to process experiments. The experimental results have shown that this method can process optical parts.

Abstract: To achieve the goal of processing large diameter and ultra-smooth optical components, the control system of the area-contact magnetorheological finishing machine is introduced. The system includes motion control systems, structural adjustment systems, detection systems and alarm systems. PLC, the core of the system, is used to data collection, input and output control, process control and so on. The touch screen as the man-machine interface is simple and intuitive, easily to operate. This paper describes the algorithms of this control system and introduces the design of the hardware and software of the system. This control system have a stability performance, strong anti-interference ability. The result shows that the magnetorheological finishing machine could processφ300mm optical components the optical components, radius range of optical components is -∞≤R-30 or 30≤R≤∞, and the surface roughness less than 1nm.