Optimum Design of Lightweight Silicon Carbide Mirror Assembly

According to the design requirement and on the basis of the principle that the thermal expansion coefficient of the support structure should match with that of the mirror, a lightweight silicon carbide primary mirror assembly was designed. Finite element analysis combined with the parameter-optimized method was used during the design. Lightweight cell and rigid rib structure were used for the mirror assembly. The static, dynamic and thermal properties of the primary mirror assembly were analyzed. It is shown that after optimization, the lightweight ratio of the silicon carbide mirror is 52.5%, and the rigidity of the silicon carbide structure is high enough to support the required mirror. When temperature changes, the deformation of the mirror surface is in proportion to the temperature difference.

Design and Coupled Thermo-Mechanical Analysis of Silicon Carbide Primary Mirror Assembly

Based on the principle that the thermal expansion coefficient of the support structure should match that of the mirror, three schemes of primary mirror assembly were designed. Of them, the first is fused silica mirror plus 4J32 flexible support plus ZTC4 support back plate, the second K9 mirror plus 4J45 flexible support plus ZTC4 support back plate, and the third SiC mirror plus SiC rigid support back plate. A coupled thermo-mechanical analysis of the three primary mirror assemblies was made with finite element method. The results show that the SiC assembly is the best of all schemes in terms of their combination properties due to its elimination of the thermal expansion mismatch between the materials. The analytical results on the cryogenic property of the SiC primary mirror assembly show a higher surface finish of the SiC mirror even under the cryogenic condition.

Design and finite element analysis of lightmass silicon carbide primary mirror

Primary mirror is one of the key components in the space remote sensing system. To minimize the mass of the mirror without compromising its stiffness and decrease the deformation of the mirror surface at the different temperatures are the mainly two objects in the development of the primary mirror. Silicon carbide (SiC), the most promising optical material, was used as the material of the primary mirror with triangle lightmass structure in a Cassegrain system. By using finite element method, the properties of the SiC mirror were compared with that of the traditional Be mirror and fused silica mirror. The results of static, dynamic and thermo-mechanical analysis indicate that the deformation of the mirror surface caused by temperature field is much bigger than that caused by gravity field. The SiC mirror has the best overall properties, and the SiC material is much suitable for the primary mirror.

Effects of light-mass structural forms on silicon carbide mirror

To reduce the mass of the mirror,silicon carbide was used as the material and four light-mass structures were designed. The properties of SiC mirror open back structure with triangular cell,open back structure with hexagonal cell,sandwich structure with triangular cell,sandwich structure with hexagonal cell,were analyzed by using finite element method. The results of the static,dynamic,and thermal properties of the four kinds of SiC mirror indicate that the surface figures of the SiC mirrors are all satisfactory with the design requirements. The properties of the mirrors with sandwich structure are better than those with open back structure,except the high cost. And the mirror with triangular cell has better combination properties than the mirror with hexagonal cell. Considering the overall performance and the cost,open back structure with triangular cell is the most suitable for the SiC mirror.

A review of manufacturing technologies for silicon carbide superjunction devices

Superjunction technology is believed to reach the optimal specific on-resistance and breakdown voltage trade-off.It has become a mainstream technology in silicon high-voltage metal oxide semiconductor field effect transistor devices.Numerous efforts have been conducted to employ the same concept in silicon carbide devices.These works are summarized here.

ManUfaCturing,Testing and Alignment of Sentinel-2MSl Telescope Mirrors

The ESA Sentinel-2 mission developed by European Aeronautic Defense and Space Compagny （EADS） Astrium will be devoted to Earth high resolution spectral imagery for the purpose of a global environmental monitoring. As a subcontractor of EADS Astrium, AMOS was responsible for the manufacturing of the instrument telescope mirrors and for the validation of the telescope alignment procedure. This paper details the mirror manufacturing sequences from mirror CVD-SiC cladding to surface figuring and coating, outlining the metrology steps and their corresponding accuracy budget. The telescope alignment process is described in connection with the tooling and techniques that helped achieve the required optical performance of less than 90 nm RMS wavefront error within the telescope field of view.Pierre Gloesenet

中国第三代半导体产业发展研究

第三代半导体广泛应用于照明、电力电子、新一代移动通信、新能源等领域,其基础性强、战略意义重大。我国第三代半导体产业链已经基本完备,市场规模逐年快速增长,且第三代半导体技术在专利布局方面也具备优势,与国际领先水平的差距不断缩小。本文对中国第三代半导体产业和技术发展现状以及发展趋势进行研判与分析,针对第三代半导体技术发展出现的问题,提出未来中国第三代半导体技术发展的思路与建议。

国内外碳化硅反射镜及系统研究进展

对几种常用反射镜材料的物理性能进行了比较,对最有发展前途的反射镜材料——碳化硅的诸多特点进行了归纳,详细介绍了国内外碳化硅反射镜制备、加工方面的研究进展以及碳化硅系统的研究现状,并对今后碳化硅反射镜及系统的发展做了简要评述。

新型反射镜材料——碳化硅

对几种常用反射镜材料的物理性能和工艺性能进行了比较 ,研究了碳化硅轻质反射镜的制作工艺 ,结果认为 :反应烧结是实现这种材料作为反射镜材料的巨大潜力的最有效的工艺 ,可以实现形状复杂产品的近净尺寸成型 ,样品在烧结过程中无收缩 ;样品处理时间短 ;无需特殊设备 ,在烧结过程中无需加压 ;样品尺寸原则上仅受烧结炉大小的限制 ,制品近乎完全致密。这项研究的突破 ,主要依赖于反射镜成型方法及反射镜面光学加工的研究进展。

SiC基陶瓷卫星反射镜研究进展

从各种卫星反射镜材料的性能和特性出发,得出SiC及其复合材料作为反射镜材料的性能最佳的结论,阐述了SiC反射镜制备工艺及方法特点,详细介绍了SiC陶瓷基卫星反射镜的国内外发展现状,最后对SiC基陶瓷卫星反射镜的发展提出了展望。

大尺寸轻型SiC光学反射镜研究进展

本文比较了光学玻璃、硅、铍 ,碳化硅等太空反射镜片材料的物理性能和机械性能 ,着重介绍了新型光学反射镜片材料碳化硅的种类、制造工艺和应用 ,并讨论了碳化硅作为太空反射镜片材料目前存在的问题及发展方向。

碳化硅反射镜轻量化结构优化设计

本文根据某型号碳化硅主反射镜的设计要求,对比了扇形、三角形、六边形轻量化孔对镜体静态、动态性能的影响,选择了综合性能较好的三角形轻量化结构方案,利用有限元方法进行参数建模,将对镜体力学性能和质量影响较大的镜体厚度、面板厚度、筋厚度等结构参数作为设计变量,运用零阶优化方法对镜体结构进行优化设计,得到了轻量化程度高、镜面变形误差完全满足设计要求的碳化硅反射镜体。

先驱体转化法连续SiC纤维国内外研究与开发现状

比较了连续ＳｉＣ纤维的四种主要制备方法，着重介绍了先驱体转化法制备工艺，并就先驱体转化法生产连续ＳｉＣ纤维国内外研究历程、开发现状、发展前景及对策作了初步的分析与探讨．

空间相机反射镜碳化硅材料性能测试

通过对SiC样件加工研磨及反射率等性质的测试,得到了材料的性能数据,分析了用SiC材料制备反射镜毛坯的几种方法的优缺点。采用Lanmda-9分光光度计,对SiC在不同表面镀硅、镀银、以及镀硅后再镀银的条件下进行了反射率测试,得出在镀硅再镀银条件下,反射率最高,达到98%的结果。利用Wyko干涉仪对国产SiC长条形样镜进行研磨分析测试,测得表面粗糙度值为6.27 nm。该材料在某型号离轴三反光学系统中作为反射镜得以应用和验证,测得被加工后,镜面面形PV值达到0.068λ,RMS值为0.01λ(λ=632.8 nm)。此结果表明,材料的性能达到了可加工可应用的要求。

快反系统中平面反射镜的轻量化设计

根据快速控制反射镜系统(快反系统)对平面反射镜的设计要求,对快反镜的轻量化结构进行了优化设计。选择比刚度大、热变形系数小的碳化硅为镜坯材料,采用背部开槽式结构减重,背部3点式支撑,对不同筋宽和镜面厚度等多种轻量化方案进行了有限元分析。结果表明:筋宽越大,镜体刚度越好,但筋宽增大到一定程度时,反射镜刚度的改善程度减缓;镜面越厚,镜体内应力、自重变形越大。结合反射镜设计要求和有限元分析结果,加工制备了筋宽为4 mm,镜面厚度为4 mm的碳化硅反射镜,镜体轻量化率达55%。实测反射镜的面形精度,其RMS值不超过λ/30,与分析结果相符,满足系统的使用要求。

碳化硅反射镜技术的研究现状

介绍了碳化硅作为最有发展前途的新型反射镜材料的特点,阐述了碳化硅反射镜的轻量化设计、坯体制备、涂层、镜面光学加工和光学检测技术的特点和国内外研究现状,以及世界各国 SiC 反射镜的应用。

SiC基反射镜制备工艺研究进展

空间系统用的高性能轻质反射镜的研究和应用正逐年稳定发展,本文从几种卫星反射镜材料的性能和特性出发,得出SiC及其复合材料作为反射镜材料性能最佳的结论;通过比较各种工艺制备SiC基反射镜性能,结果显示:只有C V D SiC能够作为反射镜反射光学表面。本文重点详细介绍了SiC及其复合材料反射镜制备工艺及方法特点,并对其工艺发展前景进行了展望。

碳化硅轻型反射镜的研究进展

反射镜材料需具有低密度、高弹性模量、高热导率和低热膨胀系数。比较了不同反射镜材料的物理性能和机械性能,与传统光学材料对比,碳化硅具有优越的物理性能和热性能,被认为是轻型反射镜材料的首选。综述了碳化硅反射镜材料常用制备方法的特点。认为反应烧结法和热等静压法适用于制备SiC反射镜基体材料,化学气相沉积法适合用于基体材料增密和制备反射层,反应烧结法结合化学气相沉积工艺是制备SiC反射镜的高效低成本工艺。

碳化硅光学镜面加工

简要介绍了碳化硅光学镜面的主要应用领域;碳化硅材料的主要物理特性和几种常用的制备方法;比较了碳化硅材料与其他常用光学镜面介质材料的主要物理性质。介绍了碳化硅光学镜面的光学加工的流程和加工手段;比较分析了碳化硅光学镜面的光学加工过程各个步骤中所应用的磨具、磨料和加工方法。讨论了光学加工过程中各个步骤工艺参数的选择和降低碳化硅光学镜面表面粗糙度的途径。最后,简介了美国、俄罗斯和我国在碳化硅反射镜的光学加工方面所取得的成果。

非球面碳化硅反射镜的加工与检测

为了获得高精度非球面碳化硅(SiC)反射镜,对非球面碳化硅反射镜基底以及改性后碳化硅反射镜表面的加工与检测技术进行了研究。介绍了非球面计算机控制光学表面成型(CCOS)技术及FSGJ-2非球面数控加工设备。采用轮廓检测法和零位补偿干涉检测法分别对碳化硅反射镜研磨和抛光阶段的面形精度进行了检测,并采用零位补偿干涉检测法及表面粗糙度测量仪对最终加工完毕的碳化硅反射镜的面形精度和表面粗糙度进行检测。测量结果表明:各项技术指标均满足设计要求,其中非球面碳化硅(SiC)反射镜实际使用口径内的面形精度(RMS值)为0.016λ(λ=0.632 8μm),表面粗糙度(RMS值)为0.85 nm。