Fundamental axial spindle motions and optical tolerancing

the production of spheres of 90-ram diameter with deviations from roundness of less than 50 nm. The roundness was measured to an uncertainty of 5-nm on a Talyrond with averaging procedures to account for spindle errors. 8 Refs. 25. Paquin, Roger A.; Gardopee, George J. Fabrication of a lightweight beryllium one-meter f/0.58 ellipsoidal mirror. Large Optics II; 1991 Oct 8. Bellingham, WA: The International Society for Optical Engineering; 1992: 61-70. VoI. 1618. A program to fabricate a large, optically fast, aspheric lightweight Be mirror was initiated in order to demonstrate state-of-the-art technology. The mirror blank was fabricated as a 1.0-m diameter, f/0.58 ellipse directly from IP-70 grade powder using nearnet-shape hot isostatic pressing (HIPing) and a patented tooling approach that produced a closed back, honeycomb-cored mirror weighing less than 18 kg. Details of the mirror design and of the assembly for HIPing are given. The blank was HIPed, leached, and machined to final shape with all design goals met. The as-HIPed blank was within plus or minus 0.5-mm in all dimensions and the radius of curvature was within 0.2% of target. The mirror was loose-abrasive ground using plunge grinding with a full-size tool, then polished using a full-size flexible pitch lap. In-process metrology utilized a special-purpose swing-arm profilometer with demonstrated accuracy and repeatability of less than 1 X at 0.63 ~m. The surface quality of the mirror was characterized by measuring the BRDF at 3.39 pro. 3 refs. 26. Poczulp, Gary A.; Stepp, Larry M.; Richardson, John H. Fabrication of the WlYN 3.5-m primary mirror: producing an accurate sphere. Large Optics//;, 1991 Oct 8. Bellingham, WA: The International Society for Optical Engineering; 1992: 3040. Vol. 1618. The National Optical Astronomy Observatories has been working to extend existing fabrication techniques necessary to polish and figure large, steeply curved, structured borosilicate glass mirrors to exceedingly close tolerances. This paper describes the generation, grinding, and polishing techniques used to transform a 3.5-m diameter, f/1.75, glass casting into a precision spherical surface. The accuracy of the finished sphere was 0.52 ~. peak-to-valley and 0.066 ;~(42 nm) rms. 27. anon. Final Report to the Office of Naval Research on Precision Engineering - 1 Oct 86 - 30 Sep 91.; 1991 Sep 30. 399 pages. The focus of the research effort in the Precision Engineering Center (North Carolina State University, Raleigh) is to improve the capability of precision manufacturing process. This focus requires research into new sensors and measurement techniques for surface characterization, in-depth studies of fabrication techniques, and hardware and software solutions for enhanced machine control. The project summaries are arranged under three broad categories: Measurement and Motion, Fabrication Techniques, and Machine Control. 28. Allen, Lynn N.; Hannon, John J.; Wambach, Richard W. Final surface error correction of an off-axis aspheric petal by ion figuring. Active and Adaptive Optical Components; 1991 Jul 24. Bellingham, WA: The International Society for Optical Engineering; 1992: 190-200. Vol. 1543. The final surface figure error correction of a 1.3-m ULE frit-bonded, ultra-lightweight, off-axis primary mirror petal was successfully completed using the ion figuring process. The petal was a concave aspheric optical element. Ion figuring is an optical fabrication method that provides highly controlled error correction of previously polished surfaces using a directed, inert and neutralized ion beam to physically sputter material from the optic surface. The surface figure error of the petal following conventional polishing was 5.02 ~. p-v, 0.62 ~. rms, and was improved to 0.17 ~.p-v, 0.15 ~, rms in four process (test-ion figure) iterations ( ~. = 632.8 nm). A multi-iteration process sequence was selected to address the various surface figure error volume and spatial frequency components and involved applying three different beam removal functions. The benefits of ion figuring a complex shaped optic using multiple figuring-testing iterations were clearly demonstrated. 5 Refs. 29. Gerchman, Mark C. Fundamental axial spindle motions and optical tolerancing. Commercial Applications of Precision Manufacturing at the Submicron Level; 1991 Nov 19. Bellingham, WA: The International Society for Optical Engineering; 1992: 49-52. Vol. 1573. This paper will examine the surface error which results as a consequence of fundamental axial spindle motion in the diamond turning process. A mathematical model of this error will be developed and contrasted with a traditional Zernike error fit. In addition, the effect of this error on the optical performance of these surfaces will be investigated. 30. anon. High-Productivity Machining Systems: A State-of-the-Art Assessment. Ann Arbor, MI: National Center for Mfg. Sciences; 1989; NCMS-88-PE-4. 520 pages. The objective of the study is to provide the National Center for Manufacturing Sciences (NCMS) management with sufficient information and recommendations to permit the identification of specific research and development (R&D) projects that can be funded by NCMS, and that will lead to competitively meaningful advancements in the area of high productivity machining systems. The following types of process equipment are included within the scope of high-productivity machining: Machining centers, Grinders, Turning and boring centers, Broaching equipment, Multiple-spindle-head equipment, Inspection equipment, Jet cutting, Laser cutting, Electrical-discharge machining (EDM), and Electrical-chemical machining (ECM). 31. Wood, A. P. Hybrid refractive-diffractive lens for manufacture by diamond turning. Commercial Applications of Precision Manufacturing at the Submicron Level; 1991 Nov 19. Bellingham, WA: The International Society for Optical Engineering; 1992: 122-128. Vol. 1573. The potential advantages of hybrid refractive-diffractive elements in infrared systems are reviewed. It is shown that these advantages can be realized in practice by single point diamond turning. Indeed, their manufacture by this process is no more complex in principle than making conventional aspherics which is a well-established technology. The design and manufacture of a zinc sulphide hybrid lens for the 3 - 5 ~tm waveband is described. 12 refs. 32. Valentino, James V. Introduction to Computer Numerical Control. P-H; 1992 Oct. 320. ISBN: 0-13-489477-4. 33. Sampson, P. G.; Sny, L. C. Introduction to Intelligent Processing Programs Developed by the Air Force Manufacturing Technology Directorate, Wright-Patterson AFB, OH: Wright Research and Development Center; 1992 Apr. 8 pages. The Air Force has numerous on-going manufacturing and integration development programs (machine tools, composites, metals, assembly, and electronics) which are instrumental in improving productivity in the aerospace industry, but more importantly, have identified strategies and technologies required for the integration of advanced processing equipment. An introduction to four current Air Force Manufacturing Technology Directorate (ManTech) manufacturing areas is provided. Research is being carried out in the following areas: (1) machining initiatives for aerospace subcontractors which provide for advanced technology and innovative manufacturing strategies to increase the capabilities of small shops; (2) innovative approaches to advance machine tool products and manufacturing processes; (3) innovative approaches to advance sensors 58

J A N U A R Y 1993 VOL 15 NO 1