Machining of Silicon Using High-speed Miniature Diamond Cutters

63, J. S. Goela, R. L. Taylor, "Large Scale Fabrication of Lightweight Si/SiC Lidar Mirrors," SPIE - Space Optical Materials and Space Qualification of Optics, Vol 1118, Orlando, FL, USA, 1989. pp. 14-24. Society of Photo-Optical Instrumentation Engineers,Bellingham, WA (USA). Small models (7.5-cm dia.) of lightweight Si/SiC mirrors have been fabricated via a scalable chemical vapor deposition process. These mirrors consist of a low f-number (f/l.6), concave faceplate of SiC coated with CVD Si, and a lightweight back-up structure made of SiC. The lightweight structure consists of an outer hexagonal cell with six triangular inner cells. The complete lightweight mirror substrate was fabricated directly in a CVD chamber, and no bonding agent was used to attach the SiC back-up structure to the faceplate. The Si/SiC mirrors were polished to a figure of l/5th of a wave and a surface finish of 10 t~ RMS. The CVD mirror fabrication process was scaled from a small horizontal research furnace to a vertical pilot-plant size CVD reactor. (Edited author abstract) 13 Refs. 64, T. Kemeny, K. Havrilla, "Laser Applications in Precision Measurement," Symposium q~ the 7'ethnical Committee TC14 Working Group on Laser Measurement: laser applications in precision measurement, (Nova Science Publishers, lnc.~ Commack, NY (USA), 1987). 265 pages. In this book, the authors consider the various coherent optical metrology techniques, data handling and processing, as well as special applications in optical engineering. Holographic and laser interferometry, as novel technologies, play a decisive role. Phenomena, as bases for technical Solutions, components and realized systems are presented and discussed. 65, A. R. Asatryan, " L a s e r Device for Measuring the Trajectories of the Moving Operating Elements of Machine Tools," Meas. Tech. (USA), 32(6), pp. 510-12. (June 1989). The high demands made on the accuracy of machine tools make it necessary to develop new methods and devices for controlling the accuracy parameters which determine the quality of the machine tool itself. One of the promising directions for solving this problem is the design of electron-optical laser measuring devices. An accurate experimental laser device developed for measuring the trajectory of movement of the operating machine elements is described. The use of the given device makes it possible to totally compensate for the errors caused by the turbulence of the air streams, instability of the radiation source itself, and also by mechanical actions of various types, and thereby to facilitate a high accuracy of measurements of the trajectory of the controlled reference point of the moving working elements of the machine tool, and thus to reliably and objectively estimate the quality of the machine tool. 66, S. Nakai, "Laser Fusion and Precision Engineering," Seimitsu Kogaku Kaishi (Japan), pp. 1917-1922. (Nov 1989) The development of laser nuclear fusion energy for attaining the self supply of energy in Japan and establishing the future perspective as the nation is based in the wide fields of high level science and technology. Therefore to its promotions large expectation is placed as the powerful traction for the development of creative science and technology which are particularly necessary in Japan. The research on laser nuclear fusion advances steadily in the elucidation of the physics of pellet implosion which is its basic concept and compressed plasma parameters. In September, 1986, the number of neutron generation l013 . and in October, 1988, the high density compression 600 times as high as solid density have been achieved. Based on these results, now the laser nuclear fusion is in the situation to begin the attainment of ignition condition for nuclear fusion and the realization of break even. The optical components, high power laser technology, fuel pellet production, high resolution measurement, the simulation of implosion using a supercomputer and so on are closely related to precision engineering. In this report, the mechanism of laser nuclear fusion, the present status of its research, and the basic technologies and precision engineering are described. (In Japanese). 67, E. L. Church, P. Z. Takacs, "Light Scattering from Surface and Subsurface Defects," (1989). 24 pages. (Brookhaven National Laboratory, BNL-44963). Light scattering is an important if unwanted effect of imperfect surface finish. It can also be used for locating, identifying and quantifying surface and subsurface defects. Similar problems have been studied for many years in the field of microwave remote sensing and much of the extensive literature in that field has direct application to the present optical problem. This paper illustrates this approach by considering two elementary applications: topographic scattering from metal surfaces, and subsurface and bulk scattering from weakly inhomogeneous transparent materials. This approach has been developed into a practical method for the quality control of high-performance mirrors, while possible applications to subsurface damage are limited by the lack of availability of controlled experimental data. 68, K. Okano, "Machining of Ceramics," Seramikkusu (Japan), pp. 195-199. (1 Mar 1990). Most of the machining of ceramics are done by grinding with diamond cutting stones. Studies on machining of ceramics are introduced, and the current status and future of machining technologies of ceramics are described. Plasma heating grinding method is under development in which ceramic is heated at high temperature and the resulting lower strength ceramic is subjected to grinding. Grinding stone with a grooved pattern and a provision for liquid passing was developed, showing a good performance of one-pass grinding finish. It is particularly suitable for use under severe machining conditions. In-process electrolysis dressing method was developed, in which the bond surface is removed by electrolytic action during processing for projecting abrasive grains. High efficient drilling method was investigated for core drill machining which employs supersonic vibration. Electric discharge machining in electrolytic solution for non-conductive materials is a well known system, and a method is under development in which neutral electrolytic solution harmless to human body is employed. 19 refs., 9 figs. (In Japanese). 69, S. T. Smith, "Machining of Silicon Using High-speed Miniature Diamond Cutters," Journal of Physics D: Applied Physics, 23(5), pp. 607-616. (May 14, 1990). This paper will present the results of an investigation into the machining of single crystal silicon using miniature diamond cutting wheels. To achieve high surface velocities and a large dynamic stiffness. cutting pins are rotated at a speed of between 90,000 and 100,000 RPM using a commercial air turbine spindle. It will be shown that surface degradation due to the grinding process is related to the dynamics of the process and, more importantly, to the geometry of the specimen/cutter interface. The surfaces generated by this process have been assessed using optical microscopy, etching, x-ray diffractometry, stylus techniques and scanning electron microscopy. This analysis provides further indications that the as-machined surface consists of an outer layer of submicrometre thickness that is under a high compressive stress. This is followed by a highly distorted and/or fractured layer that extends with decaying intensity into the bulk material. (Author abstract) 22 Refs.

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