principals for the illumination system of a DUV wafer stepper are derived by examining the coherence properties of a KrF excimer laser and the effect of DUV radiation of high energy density on fused silica, the material used for the optical components. Alternative designs are presented and discussed.

23, H. Suzuki, "Development of CNC Ultra Precision Aspheric Grinder and 3-dimensional High Precision Machining of Brittle Materials," Journal of the Japan Society of Precision Engineering, pp. 815-19. (1990). The author presents a CNC ultraprecision aspheric grinder for machining the pickup lens of a compact disc. The grinding of silicon carbide molds, which are very brittle, and cutting them to a very small depth is discussed. Optics for short wavelength light are also considered. (Japanese)

24, T. Miyoshi, T. Kondo, K. Saito, Y. Kamiya, H. Okada, "Development of Noncontact 3-D Digitizing System," Journal of the Japan Society of Precision Engineering, pp. 1021-6. (June 1990). The purpose of this paper is to develop a noncontact 3-D digitizing system using an NC machine tool which can measure and free-form surface such as 3-D model shapes for injection molds speedily and accurately. The proposed 3-D digitizing sensor has a major advantage in that the location of a light spot obtained by passing laser light scattered from a target surface through a unique lens system is linearly proportional to the displacement of the surface in optical axis. This sensor with a measuring range of 20 mm and resolution of 11 gm/pixel, can measure the displacement of a target surface within an accuracy of _+ 50 gm for steep inclined surface up to _+ 75 degrees without causing a dead angle called the shadow effect. (Japanese)

25, T. Oiwa, A. Kyusojin, "Development of Precise Cylindrical Grinding by Ball Centres. Contact Stiffness Between Ball and Centre Hole," Precision Engineering, 12(1), pp. 37-42. (Jan 1990). In high precision cylindrical grinding it is customary to support the workpiece with dead-centers. The geometrical deviations of cone centers and center holes and their misalignments have an influence on the roundness of ground surfaces. It is known that the misalignments and geometrical deviations of center holes do not influence the roundness of ground surfaces with the accurate and inexpensive steel balls in place of cone centers. In this paper, experiments on the axial and radial stiffness were performed, at the contact parts between bails and center holes. 7 Refs.

26, J. Kubler-Tesch, "Diamond Tools in Mass Production of Automobiles," Werkstattstechnik, 80(4), pp. 187-190. (Apr. 1990). Use of polycrystalline diamond (PCD) tools for machining of A1--Si alloys and of glass-fibre- and carbon-fibre- reinforced parts is discussed. Performance comparison with that of high-speed steel shows seven times higher speed of PCD tools. Graphs. 5 ref.

27, T. T. Saito, C. K. Syn, B. A. Fuchs, S. P. Velsko, "Diamond turning of optical crystals," (Lawrence Livermore National Laboratory, Mar 1990). 4 pages. (UCRL-102807). Diamond turning (DT) has proven to be a cost effective optical fabrication technique for both aspherical and spherical/flat figures when precise geometrical tolerances are important. We are interested in the DT of crystals for several reasons. DT has been very effective to insure requisite accurate geometrical orientation of optical surfaces to crystalline axes for frequency conversion applications. Also, DT can achieve figure up to the edge of the crystal. Another key DT benefit is enhanced laser damage threshold, which we feel in part is due to the freedom of the surface from polishing impurities. Several important issues for diamond turning optical crystals are the tool wear, associated surface finish, and laser damage propertie s . We have found that careful selection and control of diamond turning parameters can yield production techniques for crystals previously considered incompatible with diamond turning. 8 refs., 2 tabs.

28, L. Pukaite, "Diamonds deliver dazzling results," Machine and Tool Blue Book, 85(2), pp. 35-37. (Feb 1990). The unique properties of the diamond make it appropriate for demanding grinding and turning applications. Diamond, the hardest substance known to man, is approximately four times as hard as tungsten carbide. Diamonds also have the highest wear resistance of any cutting-tool material. (The diamond is approximately 2000 times more wear resistant than cemented tungsten carbide.) That wear resistance allows the diamond to retain its size under tremendous specific pressure at the cutting edge. Used as cutting tools, natural and manufactured diamonds are ideal for applications in which hard-to-machine materials, such as composites, generate unacceptable tool wear; conventional tooling cannot achieve the desired surface finish; and where heat may cause defects in the part during production. This article discusses Polycrystalline Diamond tools and compares property variation to those of moncrystalline diamond cutting edges. Applications are described as also the process of chipping and achieving a chipless edge on cutting tools.

29, A. Allcock, "Diamonds give smooth braking," Machinery and Production Engineering, 148(3779), pp. 89-90. (Mar 23 1990). The author tells how CLA Tools' diamond burnishing helped The Rover Group achieve smoother braking for the new Rover 200 car. Using a new single-point diamond burnisher, the surface finish is being consistently achieved within the projected cycle time and the output target of 9000 discs/week is being met. Since the machine's installation in September 1989, 4000 components/machine has been processed to Christmas 1989 with no sign of wear on the burnishing tools.

30, J. W. Dini, R. R. Donaldson, C. K. Syn, D. J. Sugg, "Diamond Tool Wear of Electrodeposited Nickel-phosphorus Alloy," 77th AESF Annual Technical Conference, Part 2, Boston, MA, USA, 9-12 Jul 1990. pp. 1315-1329. American Electroplaters & Surface Finishers Soc Inc. Orlando, FL, USA. Nickel-Phosphorus alloys are attractive materials for diamond tuming applications such as fabrication of large optics and other high precision parts. Although the mechanism is not understood, diamond tool wear is minimized when the phosphorus content of the deposit is greater than 11% (wgt). In recent years, increased attention has been directed at electrodeposition as an alternate to electroless deposition for producing Ni-P alloys. One principal advantage of the electrodeposition process is that alloys with 14-15% P can be obtained; another is that an order of magnitude greater deposition thickness can be provided if necessary. This paper compares diamond turning results for electrodeposited and electroless Ni-P alloys and shows that the electrodeposited coatings provide promising results. 28 Refs.

148 APRIL 1991 VOL 13 NO 2