Ultra-Precision Processes for Optics Manufacturing

controller products and companies. Sections 3-10 of the Study examine the most impactful technologies for the NGC program as determined from a Technology Workshop held in November, 1988. 43. Pidduck, A. J.; Nayar, V. Optical imaging of microroughness on polished silicon wafers. Applied Physics A: Sofids and Surfaces. 1991 Dec; 53(6): 557-562. The microscopic surface morphology of device quality polished silicon wafers has been imaged using laser scanning optical microscopy (SOM) in differential phase contrast (DPC) mode. The SOM-DPC technique has subnanometer vertical sensitivity and submicron lateral resolution. Surface texture was observed on all wafers examined. This was found to depend mainly on the originating wafer supplier and year of manufacture, rather than on any characteristic of the silicon material itself, and was assigned to silicon surface roughness. The amplitude of the directional 1-10 t~m wide polishing features observed on many of the as-received wafers was estimated to be in the region of 1-2 nm. An additional isotropic submicron-scale roughness (incompletely resolved optically) was present in all cases. Atomic misorientation steps were also observed on specially-prepared wafers. 27 Refs. 44. anon. Primary Standards Laboratory Report. Albuquerque, NM: Sandia National Labs.; 1992 Mar; SAND-92-0410. 30 pages. Sandia National Laboratories operates the Primary Standards Laboratory (PSL) for the Department of Energy, Albuquerque Operations Office (DOE/AL). This report summarizes metrology activities that received emphasis in the second half of 1991 and provides information on the operation of the DOE/AL system-wide Standards and Calibration Program. 45. van Wingerden, J.; Frankena, H. J.; van der Zwan, B. A. Production and measurement of superpolished surfaces, Optical Engineering. 1992 May; The influence of polishing time on the roughness of ultrasmooth bowl-feed-polished surfaces is studied. A large improvement of the surface quality is obtained within the first 10 min, but increasing the polishing time from 10 to 60 min did not yield a significant difference. A Linnik interference microscope, adapted for phase-shifting interferometry, was used for roughness measurements. Preliminary measurements have been performed with a setup determining the scattered intensity within a small solid angle. This relatively simple setup, which is also suitable for uncoated glass surfaces, clearly showed the improvement of surface quality by bowl-feed polishing. 46. Pasco, lan K. Production and testing of precision plastics optical components. Commercial Applications of Precision Manufacturing at the Submicron Level; 1991 Nov 19. Bellingham, WA: The Int. Society for Optical Engineering; 1992: 62-74. Vol. 1573. The aspheric lens has developed over many years to meet the needs of industry. Refinement in curve mathematics, methods of die surface generation, methods of moulding, up-to-date measurement techniques and mounting methods have led to the capability to produce lens elements with diffraction limited capability at economical cost. Such lenses are produced in wavelength ranges covering visible, near infrared and medium infrared. An ever widening range of products is served, and the flexibility of plastics leads us to believe that many more are possible, at cost levels unobtainable by other techniques. 47. Ichida, Yoshio; Kishi, Kozo; Hasuda, Yuichi. Study on one-pass mirror finish grinding technology of fine ceramics

(1st report). Development of new metal bonded fine grain diamond wheels and their application to mirror finish grinding. Journal of the Japan Society of Precision Engineering. 1992 Mar; 58(3): 463-470. In this study, a high-efficiency mirror finishing method which is named 'one-pass mirror finish grinding' has been discussed, in which the mirror finishing is accomplished by only one pass grinding operation. In this report, a metal bonded fine grain diamond wheel (MU diamond wheel) has been newly developed by using a high tin bronze bond and its grinding performance has been investigated to establish the one-pass mirror finish grinding technology for various fine ceramics. Main results are summarized as follows: (1) In grinding the representative fine ceramics such as AI203-TiC, SiC and Si3N4, the MU diamond wheels can generate the mirror surface with roughness of 30-80-nm Rmax by only one pass grinding operation, in which the material removal rate reaches 4-10 mm3/mm center dot min. (2) As the MU diamond wheels have an excellent ability for keeping the grinding sharpness as well as a high wear resistance, in grinding AI203-TiC ceramics, they can continue over a long time to generate the mirror surface with roughness of less than 50-nm Rmax without dressing and in this case the grinding ratio reaches about 400.6 Refs. In Japanese. 48. Estler, W. T.; Evans, C. J. Surface Figure Metrology for X-Ray Optics. Topical Meeting on Soft-X-Ray Projection Lithography;, 1991 Apr 10; Monterey, CA.: OSA; 1992 May 22: 145-146. Vol. 12. A soft-X-ray projection lithography system will require diffraction limited performance at wavelengths near 13 nm. A typical conceptual design for such a system consists of an x-ray source, a reflecting mask, and a series of normal incidence, multilayer coated mirrors used to image the mask upon a resist-coated wafer. System throughput and image field flatness demands will require aspheric mirrors with figure accuracies of / 200 or better at 633 nm. Commercial phase measuring interferometers (PMIs) offer X / 1000 resolution and, with care, X / 300 repeatability. For flats and spheres, absolute figure accuracy is limited by one's knowledge of the reference optics, since such PMIs are differential devices. At the National Institute of Standards and Technology (NIST) our present absolute figure uncertainty is about ~. / 20 for flats up to 150-mm in diameter and no better than ~./10 or so for spheres. For an asphere, compared with a reference sphere of no more than a few waves of figure departure, we can perhaps attain an absolute accuracy of X / 5 or so, but we are fundamentally limited by errors in the interferometer system due to non-common mode optical paths of the test and reference beams. At NIST, we are in the initial phases of a five-year program aimed at improving the accuracy of optical figure measurements as a part of an Institute Competence Program in support of X-ray lithography. 49. Lindsey, Kevin. Tetraform grinding. Commercial Applications of Precision Manufacturing at the Submicron Level, 1991 Nov 19. Bellingham, WA: The International Society for Optical Engineering; 1992: 129-135. Vol. 1573. Tetraform ® is a patented group of concepts which can be used to produce extremely high static stiffness and dynamic stiffness structures. A prototype machine tool, called Tetraform 1, has successfully demonstrated the concepts' advantages by grinding optical glasses and quartz to optical quality, at relatively high stock removal rates. The concepts, demonstrated by these grinding results, may be as applicable to high-speed and heavy machining as to ultra-precision and precision optical machining. 4 refs. 50. Martin, W. R. Ultra-Precision Processes for Optics Manufacturing, Oak Ridge, TN: Oak Ridge National Lab; 1991 Dec. 10 pages. The Optics MODIL (Manufacturing Operations Development and Integration Laboratory) is developing advanced manufacturing technologies for fabrication of ultra precision optical components, aiming for a ten-fold improvement in precision and a shortening of the scheduled lead time. Current work focuses on diamond single point turning, ductile grinding, ion milling, and in / on process metrology. 60

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