Deep UV Optics for Excimer Laser Systems

17, G. Hull-Allen, G. Gunnarsson, " C o m p u t e r Controlled Polisher for Advanced F a b r i c a t i o n , " Photonics Spectra, 24(3), pp. 147-8, 150, 152, 154, 156. (Mar 1990). The authors report the development of a new computer-controlled polisher (CCP) that produces exceptionally low mid-frequency error (approximately 35 Arms), has been used to correct figure errors of less than mm period, has held an optic's surface to better than 0.02 lambda P-P to within 2.0 mm from the edge of an optic, and has produced surface finishes of less than 10 A r m s on Zerodur. This new CCP was used to produce the mirrors for ttle Solar-A Soft X-Ray Telescope (SXT), a umque telescope with two hyperbolic surfaces on a single Zerodur substrate. During x-ray testing at NASA's Marshall Space Flight Center, the telescope demonstrated better encircled energy performance than previous solar x-ray telescopes because of the successful reduction of scatter, which in turn is a direct consequence of minimal mid-frequency figure error and low microroughness. 18, E. J. Danielewicz, D. Selman, " C o m p u t e r Generated Holograms Test Aspheric Optics," Laser b'ocus World (USA j, 26(4), pp. 143-4, 146-7. (April 1990). The use of single-point diamond turning has revolutionized the mass production of precision aspheric lenses, The successful application of computer-generated holographic interferometry to the testing of diamond-turned aspheric focusing lenses for industrial CO 2 lasers is discussed. CGHs produce an aspheric reference wavefront and overcome the manufacturing and testing difficulties associated with aspheric lenses. 19, A. I. Grabchenko, I. N. Pyzhov, E. D. Morshtein, " C o n t r o l of the Cutting Relief of Diamond Wheels in Machining Very H a r d Materials," Soviet Journal of Superhard Materials, 11(6), pp. 41-44. (1989). It is shown that when there is hardly any penetration of a diamond into the workpiece material only the most prominent grains make contact with it. The machining output attains a maximum at a certain critical height of projection H c, which must be maintained constantly. A mechanical device which ensures stability of the wheel cutting relief throughout its period of operation is described. 4 Refs. 20, F. N. Goodall, R. A. Lawes, G. G. Arthur, "Deep UV Optics for Exeimer Laser Systems," Microelectronic Engineering, 11(1-4), pp. 187-195. (Apr 1990). The high irradiance at short wavelengths provided by Excimer Lasers has applications in conventional lithography, micromachining and laser chemical processing. In each case a new generation and type of projection optics will be required. In this paper, the problems of lens design in the deep uv for each of the above areas are reviewed. Emphasis is given to the practical designs actually constructed and results achieved at the Rutherford Appleton Laboratory. For some designs, diffraction limited imagery over large fields is shown to be possible. The theoretical and practical work reported here shows that certain catadioptric systems are sufficiently broadband to obviate the need to line-narrow the laser. (Author abstract) 4 Refs. Presented at 15th International Conference on Microlithography. 21, Y. Altintas, J. Peng, "Design and Analysis of a Modular CNC System," Comput. lnd, (NetheHands), 13(4), pp. 30516. (March 1990). Recent focus of manufacturing research has been in the development of unmanned machining systems. Modular computer numerical control (CNC) units, which control and monitor many tightly coupled machining tasks, are required. The paper describes the detailed design and analysis of a modular, research CNC system for a milling machine. The feed drive servo of the milling machine consists of continuous and digital position control blocks. Continuous and discrete transfer functions of the complete system are derived and experimentally verified. A state space model of a feed drive servo is developed for a time domain analysis of actual position, velocity and armature current for given position input and machining force disturbances. A complete experimental verification of the system's model is presented. 22, A. S. Savel'ev, M. P. Maksakova, A. P. Semenov, M. A. Abdulkadyrov, R. R. Asadulin, "Determination of the Polishing Coefficient of Glass," Sov. J. Opt. Technol. (USA), 56(9), pp. 561-3. (Sept 1989). A method is described for determining the polishing coefficient of glass, independent of the adjustment parameters of the lathe and the tool diameter and construction. Specific recommendations are given with respect to using the described method. 23, K. Isomura, T. Funahashi, R. Uchimura, "Development of Machinable Si3N4-BN Composite Ceramics," KawasaM Steel Giho, 21(4), pp. 17-22. (1989). Advanced composite ceramics of the Si3N4-BN system have been developed. The Si3N4-BN composite ceramics (SNB) have been produced using a slipcasting technique, which utilizes homogeneous mixing of ultra-fine constituent ceramic powders, and N 2 gas pressure sintering. An essential feature of SNB is that it is possible to change widely their various properties by controlling the proportion of BN to Si3N 4 . The advantageous features of SNB are high thermal shock resistance, high corrosion resistance to molten metal, and excellent machinability while retaining relatively high strength, i.e., the bending strength of SNB with 20 wt. % BN is 200 MPa or over. The thermal shock resistance temperature is improved by 250 to 300C compared with Si3N4 monolithic ceramics by incorporating 20 wt. % BN. These features indicate that SNB are well suited to machine parts for various molten casting facilities and jigs for heat treatment. 24, K. Sakakibara, T. Asai, Y. Ozawa, A. Nagakura, N. Kojima, S. lgarashi, "Development of Smoothly Curved Fresnel Lens," SAE International Congress and Exposition - Vehicle Lighting and Driver Visibility for the 1990~, Vol 813, Detroit, MI, USA, 1990. pp. 43-51. SAE, Warrendale, PA, USA. This paper gives a detailed report on the development of the curved Fresnel lens which makes it possible to control luminous flux in a smoothly curved configuration, and thus can provide a means of illuminating the curved comer of the signalling lamp. It also eliminates the lines separating planes in the conventional design, thus improving the overall appearance of the lamp. Furthermore, the smoothly curved Fresnel lens has applications in fields other than automobile manufacturing. (Edited author abstract) 1 Ref. 25, F. Mason, "Diamond: the Material of the Future," Am. Mach., 134(2), pp. 43-46. (Feb 1990). Diamond thin films are finding increasing use for metal-cutting tools, semiconductors and military optics. The requirements for diamond-coated cutting tools are a well-crystallized diamond film of high hardness and wear resistance and strong adhesion to the substrate to withstand flaking. The last requirement is the one providing the greatest challenge. Examples are given of the application of diamond-coated inserts for the turning of die cast A1 alloys and a sintered Cu-10Sn alloy, and the face milling of a graphite board.

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J A N U A R Y 1991 VOL 13 NO 1