22. Tianning Cao; Jianping Zhang. Computer-controlled polishing of aapherlc surfaces. SPIE - International Symposium on Optical Fabrication, Testing, and Surface Evaluation; 1992 Jun 10; Tokyo, Japan. Bellingham, WA: International Society for Optical Engineering; 1992. 60-65. A computer controlled generation of rotationally symmetric aspheric surfaces is presented, which accurately predicts material removal rates with a X-Y type computer-controlled polishing system and a small polishing tool. According to theoretical calculation, ~ 300 mm spheric surface (r = 2090) is figured into a ~p 300 mm f/3.5 parabolic surface along 10 concentric circle areas in 30.8 hrs. A surface accuracy of ;L/8 (rms) can be obtained. After analysis of the techniques and experimental results, it is concluded that the double rotation tool polishing removal profile is the key parameter. To ensure optical surface quality, different polishing paths, optimized operating parameters and adequate detecting systems are required for polishing of different aspheric surfaces. A computer model of the polishing process was developed and used to investigate the removal profile of various tool shapes and different polishing parameters from the model.

23. Ro, Paul I.; Abler, Jeffrey A. Control of ultra-precision diamond turning process. Proceedings of the 1992 Japan - USA Symposium on Flexible Automation. Part 2 (of 2); 1992 Jul 13. New York, NY: ASME; 1992: 1513-1519. When driving a lightly damped system with a servo motor, the design of a controller which reduces disturbance excited vibration can be undermined by the need to maintain the system bandwidth to achieve good tracking performance. The use of classical lag / lead compensation and conventional filtering techniques to dampen the oscillatory modes often has adverse effects on the system bandwidth, A control scheme designated as 'directional damping control' is developed using classical root locus and frequency response techniques for systems with a lightly damped mode at a frequency considerably higher than the servo bandwidth. The scheme separates the design of the system bandwidth from that of the damping of the highly under-damped mode. The design procedure is first presented for the general case, followed by design and implementation as a slide motion controller for precision machining. Using the scheme, the slide vibration is significantly less than when using conventional PID control, and a corresponding improvement is seen in the surface roughness of machined parts. 11 Refs.

24. Roberts, C. J.; Wilkins, M. J.; Beamson, G.; Davies, M. C.; Jackson, D. E.; Scholes, P. D.; Tendler, S. J. B.; Williams, P. M. The demonstration of controlled surface modification achievable with a scanning tunneling microscope on graphite, metallic films, organic molecules and polymeric biomolecules. Nanotechnology. 1992 Apr; The structural alteration of surfaces which can be initiated by the probe of a scanning tunneling microscope during the imaging process represents an important effect to account for when recording or interpreting scan data. With this in mind, the authors have attempted to demonstrate, and quantify for various surfaces, two specific types of controlled damage that can be caused with a scanning tunneling microscope. Firstly, areas of surface damage caused by scanning with a low tunneling gap resistance, and hence with the tip 'close' to the sample, are demonstrated for gold films, platinum-carbon films, an organic molecule, and a polymeric biomolecule, both naked and coated in gold. The use of the smaller and less mobile grains of a platinum-carbon film to coat biomolecules also was shown to effectively eliminate this effect in the case of xanthan gum. Secondly, damage which occurs at a high tunneling gap voltages has been used to produce sharply defined depressed features in both gold and platinum-carbon films and highly oriented pyrolytic graphite. In addition raised features on the platinum-carbon films have been produced using this technique.

25. Pazol, Brian G.; DeVito, Richard; Giguere, Philip J.; Kiefner, Paul S. Development of sapphire windows for use In high-quality IR Imaging systems. SPIE - Window and Dome Technologies and Materials III; 1992 Jul 22. Bellingham, WA: International Society for Optical Engineering; 1992: 55-65. Vol. 1760. A polishing process for fabricating high-quality optical sapphire windows is presented. This process was successfully used to produce very high aspect ratio, as high as 1500:1, sapphire windows for use in optical imaging systems. During the development of the process an unusual print-through phenomenon was discussed. This replication of surface features on the blocking bodies, such as bumps or grooves, onto the polished window surface produced distortion in the final wavefront and degraded window performance. A method of bonding smaller, thick sapphire panes into a larger optical window is also presented. A glass fritting process utilizing two different temperature frits is discussed. The optical errors encountered during fritting which contribute to the optical error budget and methods for minimizing their effect on the wavefront of the final window are also reviewed. An 8' diameter by 0.435' thick optical sapphire window was produced using this fritting technology. 2 refs.

26. anon. Diamond turning: Machine development and optical mirror fabrication. (Latest citations from the NTIS database). Published Search. 1992 Nov; PB-93-854016/XAB. 10 pages. The bibliography contains citations concerning the development of diamond turning machines (DTM) and processes, which are used in the fabrication of optical devices. Diamond turning is a rapidly developing technology for high precision, high quality, and cost effective fabrication of optical reflectors, including high power laser mirrors. Topics include optical evaluations and characteristics of diamond turned surfaces, high surface accuracy with numerically controlled DTM, diamond turned metal mirrors, single point DTM, size capabilities of DTM, and x-ray DTM systems. Diamond turning research activities at several national laboratories and cosponsorships with the Department of Defense (DOD) and Department of Energy (DOE) are presented. Computer aided design and manufacturing of optical equipment is excluded and examined in a separate bibliography. (Contains a minimum of 117 citations and includes a subject term index and title list.).

27. Fuchs, B. A.; Syn, C.; Velsko, S. P. Diamond turning of l i thium niobate for optical applications. App l i ed Optics. 1992 Sep 20; 31(27) We have investigated the surfae finishing of lithium niobate by using the single-point diamond turning technique. Surface finishes of better than 5 nm rms on z-oriented samples have been achieved. However, tool wear and spalling are much more significant with lithium niobate than with materials such as the crystals KDP and LAP. We present preliminary results comparing the optical damage thresholds of polished and diamond-turned samples.

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