Papers by Keyword: Mirror

Abstract: We report on an ambitious project in the field of automation, applied to bound and free abrasive processing of precision and ultra-precision surfaces, with potentially far-reaching consequences. This involves two main aspects:- directly processing surfaces using industrial robots, and combining robots with Zeeko CNC polishing machines to automate operations that are currently manual. These form steps towards our ultimate vision of the Integrated Manufacturing Cell for bespoke optics rather than mass-produced, and manufacture of other precision surfaces including prosthetic joint implants. Projects such as the European Extremely Large Telescope provide a relevant case study, where significant numbers of high-value bespoke optics are required.

Abstract: This paper describes the application of loose-abrasive processes to the manufacture of 1.4 meter, off-axis aspheric, hexagonal mirror-segments. These are prototypes for the 39 m European Extremely Large Telescope (E-ELT). The application of active forces to correct the overall form of segments in the telescope, means that the overall form-accuracy achieved in polishing can be less critical than for a non-active mirror. However, it is a requirement that the base-radii and conic constants of mirror-segments are very closely matched, so that the combined image is not degraded. This means that abrasive processes have to operate with respect to an absolute rather than relative datum. Furthermore, there are stringent requirements on mid-spatial frequency defects on segment surfaces, and on edge-roll. These control stray-light, and ultimately detectability of faint astronomical targets. We describe the CNC abrasive techniques we have developed in response. We then demonstrate the success of the approach, which represents the first time ever that segments have been processed entirely in the hexagonal shape:- a milestone in loose-abrasive processing. Finally, we address up-scale for the unprecedented number of segments required for the E-ELT build-phase.

Abstract: This paper has described the status and role of the strapdown mirror control technology. It has analyzed the emphasis and difficulty in the study. In order to achieve higher system reliability and improve performance and eliminate all kinds of error of strapdown stable platform process what are stabilization while reducing the volume. In-depth analysis of the swing ship is on strapdown platform and mirror effect. The boat rocking and the sight stabilization mathematical model of mirror rotating. A study on the simulation what uses the MATLAB. By establishing the model of boat rocking, what analysis of the swings influence on the mirror steady accuracy and tracking accuracy. The existing stable servo control and principle has been detailed analysis. Through the simulation studies what compared their advantages and disadvantages. Also it has studied the coning error compensation method and the kalman filtering what influenced on the accuracy of strapdown mirror control system.

Abstract: As the technology of intelligent substation is developed gradually, the significance of he Ethernet switch in the substation is obvious increasingly.Firstly, the learning and transmitting principle of Ethernet frame are introduced, then the network program of secondary system using the switch in the hierarchial structure is described. And then a detailed analysis of the VLAN, QoS, mirror and ring network is given, also the various technical application scheme are provided according to a variety of IED features and data flow characteristics. On the basis of the different business needs and different message types, the reasonable design of network topology and the flexible use of these switching technology , can support security, stability, reliable transmission of communication message in intelligent substation , therefore the whole substation becomes more strong.

Abstract: Parabolic trough solar thermal power generation technology is the most mature technology in the world, which is also the only commercial operation of the solar thermal power generation technology. In order to the structure characteristics of the collector was accurately simulated and the result was calculated to reflect the performance of collector, the whole model of collector established. The internal force and deformation of steel under the external load was analyzed by nonlinear finite element method. For the connection problems of rectangular frame and mirror of the collector, the strength and rigidity of collector mirror were calculated by the finite element software for ANSYS, Which Ensured that the installation process of the collector remained unaffected to Mirror lateral displacement. While checking the shear strength of the connection bolts to ensure the collector's safety working, and to provide a useful reference for large-scale production of the solar Collector.

Abstract: The Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) is a quasi-meridian reflecting Schmidt telescope laid down on the ground with its optical axis fixed in the meridian plane and the telescope will be the one that possesses the highest spectrum acquiring rate in the world. To secure its smooth operation, each component, especially the mirror system needs to be maintained in a good condition. Some equipment is needed and the operation must be considered at early stages. In this paper, a feasible approach is put forward in which the concept of human and machine cooperative work is used to assure the successful operation at lower cost. An electrical driven forklift with some special fixtures designed for this work is used for MB mirror system and a special designed crane is used for the assembly and disassembly of MA mirror system. Procedures and methodologies for the identification of assembly and disassembly sequence, special tool design, time and cost analysis, and human factors analysis of the assembly and disassembly sequence are presented.

Abstract: The deformations of the 600mm aperture interferometer mirrors induced by gravity and supporting forces must be controlled strictly to ensure the accuracy of the large aperture interferometer to achieve 63nm. The mirror deformations induced by two types of forces and four axial distribution positions are analyzed respectively by finite element method. And the deformed interference wavefront are simulated by synthesizing deformations of reference flat and test flat mirrors. The maximum deformed interference wavefront formed by the cosine wave force at the middle of the mirrors and the minimum formed by the square wave force at the periphery of the mirrors. The peak to valley value varies 30nm and root mean square value varies 2.8nm between them. The measurement accuracy of large aperture interferometers can be improved by adjusting the force distributions and supporting positions of the mirrors according to the analysis.

Abstract: In order to keep step with new materials mirrors and its technology of developed of international space optics system, and promote research level of national new material mirror, the optimization methods of new mirror materials were introduced, and the application of new material mirrors was elaborated. The researching technologies and methods of new materials mirror substrate were recommended. The researching technologies and methods of new materials mirror were narrated. And at same time, the new materials mirror technology and directions of our country were pointed out.

Abstract: Spherical silicon balls are applied to photovoltaic energy conversion. Silicon balls are produced by droplet spray method as well as abrasive machining of a single crystalline silicon wafer. A reflective mirror is used to maximize the solar cell efficiency. It is demonstrated the solar cell efficiency depends on the crystalline structure of silicon balls and the mirror in the module.

Abstract: Silicon carbide ceramic has many attributes including high strength and stiffness, low thermal expansion coefficient, high thermal conductivity, low density and good resistant for radiation of space particles. These attributes make SiC ceramic becoming the third generation space mirror material. This paper describes the fabrication of lightweight SiC mirror blanks. By reducing the shrinkage of green body and controlling the drying conditions, lightweight SiC mirror blank with a diameter of 612mm has been prepared by using gelcasting process. The forming green body is infiltrated with liquid silicon at the temperature of 1600°C, then a CVD SiC layer is coated on the surface of SiC mirror blank. After grinding and polishing, the mirror shows good optical properties.