Manufacture Of Optical Glass Research Articles

Intelligent assessment of subsurface cracks in optical glass generated in mechanical grinding process

Grinding process of optical glass has been reported to be related with the creation of subsurface cracks. However, for the time being, most measurement methods have been depended on human operations. In this paper, an intelligent assessment method based on image processing technique is proposed. Grinding trials proved that, the proposed method can accurately (with the biggest relative error of 3.53%) and quickly (nearly 1.6 seconds per micrographs) recognize and measure the subsurface crack depths. More importantly, the proposed method has good robustness to different-sized images. Besides, the method does not require any input parameters or any adjustment of thresholds, therefore the method does not require any prior knowledge of either mechanical grinding process or brittle material behaviors relating with subsurface cracks. Based on above, the proposed method is expected to be meaningful to both metrology equipment companies and optical glass manufacturers.

Prism-pair interferometer for precise measurement of the refractive index of optical glass by using a spectrum lamp.

A prism-pair interferometer for a spectrum lamp was developed for precise measurement of the refractive index of a prism of optical glass. Previously we reported the prism-pair interferometer with a He-Ne laser light source, resulting in a measurement uncertainty of 1.1×10⁻⁶. However, most of the refractive-index values managed by optical glass manufacturers are conventionally measured with spectrum lamps. We have optimized the prism-pair interferometer for spectrum lamps and implemented a signal-processing technique from Fourier-transform spectroscopy. When the refractive index is measured, the wavelength of the spectrum lamp is simultaneously calibrated by part of the interferometer, so that the resulting refractive index is traceable to a national standard of length. The combined standard uncertainty for a refractive index measured with the e-line (546 nm) of a Hg lamp is 6.9×10⁻⁶.

A note on the manufacture and inspection of optical glass

It has been universally acknowledged that optical glass is a strategic material of vital importance, both during peace and war. This is particularly so from the point of view of the defence needs of a country and the importance of being self-dependent in a matter of this kind for a large independent country like India cannot perhaps be over-emphasized. As India does not yet possess any internal source of supply of optical glass, it is thought that it might be of some interest to give here few notes of a practical nature collected by the author personally during his recent visits to some foreign factories including one of world's leading optical glass manufacturers.

Optical glass compatibility for the design of apochromatic systems

The design of apochromatic systems is difficult because of two problems: the glass sorts compatibility and the c1/ca arbitrary input ratio. The optical glass manufacturers offer a wide range of sorts, so that the choice of triplet compatible glasses becomes itself an important separate problem. The paper provides a solution of mathematical modeling for the glass compatibility and, practically, analyses the sorts presented by Schott GmbH. The original software provided 22 compatible glass triplets. The authors explored the possibilities of enlarging the c1/ca ratio from the value 0.6 indicated in the literature to a range of [0.5?0.8]. Therefore, they designed and analyzed a set of 88 triplets. A correct glass choice can insure twice-larger apertures than the traditional ones for best quality apochromats (diffraction-limited).

2. The Carnegie Mission and Vision of Science: Institutional Contexts of Maya Archaeology and Espionage

2. The Carnegie Mission and Vision of ScienceInstitutional Contexts of Maya Archaeology and Espionage Quetzil E. Castañeda (bio) In the United States, the major alternative [to Rockefeller funding of anthropology] came from the Carnegie Institution, which was heavily oriented to physical anthropology and archaeology; such general ethnographic work as it sustained was an outgrowth of its interests in Mayan archaeology. George W. Stocking Jr., Philanthropoids and Vanishing Cultures The war work of the Carnegie Institution covered many fields of activity, from the manufacture of optical glass to military intelligence work, and to it all Dr. Woodward offered the most effective support. He himself was a member of the Naval Consulting Board. Fred E. Wright, Memorial of Robert Simpson Woodward When the history of the proceedings of the institution comes to be written there will be a fine chapter of patriotic service to the Government in reference to this matter. CIW President Robert S. Woodward, Minutes of the Meeting of the Board of Trustees This essay, while not a "fine chapter of patriotic service," does contribute toward an anthropological history of the Carnegie Institution of Washington (CIW; also known officially as Carnegie Institution or CI). The CIW (also referred to here as "the Carnegie") was founded, with a deed of $10 million in steel stock in 1902, as a research institute during the formative period of U.S. science.1 The CIW participated in the general emergence of a public sphere that was driven by the great philanthropic foundations and initiatives of the first decades of the 20th century. It was part of the emergence of a new governmentality that was to transform citizen and society along the rational lines of scientific knowledge. As a part of its scientific mission, it supported research in many, but not all, areas of science, including archaeology and, eventually, social anthropology. The legacy of the Carnegie also includes, to a great extent, the shaping of both the U.S. [End Page 27] military–industrial complex and the shaping of the contemporary structure of scientific research in the United States. As is well known, CIW president Vannevar Bush orchestrated the collaboration of science, industry, and military during World War II and then forged the development of the National Research Foundation (Bush 1990; Zachary 1999). Less known, however, is that the second CIW president, Robert S. Woodward, had already established institutional precedent for how science and scientists would contribute to the U.S. government during war time. The wide ranging and profound importance of the CIW in many areas of science and society has motivated many studies that focus on specific aspects and problems in the history of the institution and of some specific sciences. While the results of the CIW support of archaeology is not quite as monumental as the million-dollar observatories and laboratories that the Carnegie built and operates, the Carnegie sponsorship of "pan-scientific" research in Mesoamerica and the Maya world is a fundamental watershed for Americanist anthropology. Despite this indisputable importance, a sustained study of this history of the field in the manner of a "sociology of knowledge" is curiously absent. In part this may have to do precisely with the role of the Carnegie in initiating espionage by scientists, specifically by archaeologists. However, if such a silence might stop some from "digging up the dirt" on archaeology, it also effectively "buries" the intellectual specificity and unique contribution of the Carnegie-sponsored Maya research. For example, Stocking is able, as in the epigraph at the beginning of this essay, to reduce and dismiss the complexity, diversity, and specificity of 44 years of Carnegie Mesoamerican archaeological research (see also Stocking 1992:156–57; Castañeda 2003, n.d.). The CIW sponsorship of wide-ranging "pan-scientific" research and interdisciplinary "cooperation" is something of a unique and significant, if also relatively short-lived and narrowly focused, experiment in anthropology. Not a school nor a tradition nor a paradigm, the Carnegie anthropological research program was a distinct way of doing anthropology that has since been absorbed into the university-based science and its associated historiography. To recuperate this "minor literature," it is necessary to "excavate" it from the intellectual histories that marginalize and...

Mechanization of Glass Manufacture

Mechanization of glass manufacture had just begun in 1898 but was accelerating. Notable advances were soon to be made in all branches of the industry, many of them in the United States, and have continued to the present day. M. J. Owens occupies a unique position as the inventor of the first successful fully automatic container machine in 1903; he was also involved in several other important developments. However, within 20 years, machines fed with gobs supplied by the Peiler forehearth and gob feeder, also American inventions, became successful competitors. From about 1930 to 1960, a wide variety of machines was used to make containers, but these have been superseded nearly everywhere by the individual section machine, another American invention. The Lubbers process for sheet glass cylinders was an early success in 1903. About 12 years later the direct drawing of flat sheet was developed almost simultaneously by Fourcault in Belgium and Colburn in the United States. The Pittsburgh process followed a few years later. Ford was the first to succeed in making continuously cast plate, but Pilkington in the United Kingdom soon exploited that process to make much wider cast plate. At that time Pilkington also developed the simultaneous grinding of both faces of the continuous ribbon. The invention and development of float glass by Pilkington in the 1950s has made all other flat glass processes obsolete for most purposes. Owens‐Corning has played a major role in the glass‐fiber industry since its beginnings in the 1930s. The most important advance in manufacture of optical glass was the small continuous tank with vigorous stirring developed by Corning Glass Works. Corning also made other notable advances, such as the ribbon machine for lamp bulbs and the lamination process used for Corelle ware.

Use of feldspar concentrate in the manufacture of optical glass

It was found that feldspar concentrate can be used instead of up to 51% of the quartz sand in batches of optical glasses close in properties of LK4 light crown and K8 crown glasses.

Platinum for Glass Making at Jena

The use of platinum for the preparation of optical glass can be traced back to Michael Faraday who, in 1824, investigated ways of improving the manufacture of optical glass. During this work he began to use platinum for containment vessels, stirrers and ladles. Prior to this Johann Wolfgang Döbereiner had been appointed Professor of Chemistry at the University of Jena and was later supplied with platinum crucibles by his patrons. Crucibles and stirrers made from platinum were also used when Otto Schott was collaborating with Ernst Abbe on the development of new optical glasses. Their work led to a revolutionary upsurge in the optical industry in Jena and, following the involvement of Carl and Roderich Zeiss, the establishment of a reputation for optical-mechanical excellence which has been maintained ever since.

Michael Faraday’s Use of Platinum in His Researches on Optical Glass

In 1824, the British government sought to keep pace with continental advances in optical glass manufacture by funding research into the area. Faraday was put in charge of the experimental investigation and he relied heavily on platinum for vessels and instruments. Throughout the researches he was aided by William Hyde Wollaston, who manufactured and supplied the platinum initially used.

Modern British Ophthalmic and Optical Glass Manufacture

Modern British Ophthalmic and Optical Glass Manufacture

MANUFACTURE OF OPTICAL GLASS

THE production of optical glass is one of the most difficult as well as one of the most interesting of manufacturing processes. Fraunhofer was the first to realize the necessity for improvement in the manufacture of glass in order to bring it to the necessary degree of homogeneity and to make it free from internal strain, essential requirements for optical glass. It may be said that it has taken more than a hundred and fifty years to bring the art of optical glass manufacture to its present state. Messrs. Chance Bros, have been engaged on the task for nearly a hundred and twenty years and the Chance-Parsons optical glass embodies their experience, together with the newer research work in their laboratories as well as that of the firm owned by the late Sir Charles Parsons, under whom notable advances were made.

Plastics and the Glass Industry

IN his address to the Fifth Glass Convention held last week at Droitwich under the presidency of Mr. H. S. Williams-Thomas, Dr. V. E. Yarsleystressed the view that plastics are not to be regarded as substitutes for the older materials, glass, wood and metals. Much of the work done on the new transparent plastic materials such as the methacrylate and polystyrol products has been inspired by glass. In aircraft construction, where low weight must combine with security and good optical properties over a wide range of temperature conditions, 'organic glass' has no rival. The technique of the manipulation of these materials has progressed very considerably, but, as was brought out in discussion afterwards, not sufficiently to enable a bottle, for example, to be blown from a plastic mass in the manner in which molten glass is manipulated by fully automatic machinery. Much interest was aroused by the reference by Dr. A. Caress to the optical and other properties of materials of the ‘Perspex’ type, and Drs. W. M. Hampton and J. C. Peddle pointed out the tremendous range of optical properties furnished by the optical glass manufacturers to comply with the requirements of the instrument makers, and the need for both homogeneity and very precise annealing. It appears that as yet the only serious competition that might be feared in this field is in the manufacture of ophthalmic lenses, and mass-produced lenses of the type usedin very cheap cameras.

Optical Glass at the National Bureau of Standards*†

A brief resumé is given of the work done by the National Bureau of Standards in connection with the manufacture of optical glass. The method of inspection for striae is outlined, data on the reproducibility of refractivity, from melt to melt, are given, and some effects of annealing on refractivity are mentioned. Attention is directed to the fact that the raw materials needed for the manufacture of optical glass are all domestically available.

Exhibition of Microscopes

MESSRS. W. WATSON AND SONS, LTD., have arranged an exhibition of microscopes to be held in the Central Hall, Westminster, London, S.W.I, on December 9-14. A large number of representative microscopes will be on view, many with prepared slides already mounted. The object of the exhibition is not only to popularise the microscope, but also to demonstrate its utility in various forms of scientific inquiry, in biology, geology, metallurgy, etc. Some telescopes will also be on view. Messrs. Chance Bros, will exhibit various glass products and Messrs. Kodak will exhibit different types of photomicrographs. The Quekett Club is arranging an exhibition of various slides, including specimens of living pond life. During the exhibition, the following lectures will be delivered: “The Part the Microscope plays in. the Scientific Control of the Railway”, by T. H. Turner, on December 10; “The Microscopist at the Seaside”, by Martin Duncan, on December 11; “The Manufacture of Optical Glass”, by H. C. Rands, on December 12. The lectures are at 7 p.m. The exhibition is open to the public free of charge. Catalogues and further information can be obtained from Messrs. W. Watson and Sons, Ltd., 313 High Holborn, London, W.C.1.

Modern Ophthalmic Lenses and Optical Glass.

This work differs from other books on the same subject in that it is concerned chiefly with the various types of lenses and glasses which are at present available for filling the refractionist's prescriptions. The introductory chapters, which are short but adequate, deal with the history of glass, the manufacture of optical glass, the history of lenses and spectacles, the theory of lens action and the types of aberrations which occur in ophthalmic lenses. As Obrig notes, one reason for the high cost of lenses is the fact that only about 50 pounds (22.7 Kg.) of finished lenses are obtained from an original melt of 600 pounds (272.4 Kg.) of glass, while for certain types of bifocal lenses, only 12 (5.4 Kg.) pounds of finished lenses are obtained from the same original melt of 600 pounds. The succeeding chapters give brief but adequate descriptions of: (1) the properties and

THE MANUFACTURE OF OPTICAL GLASS

THE MANUFACTURE OF OPTICAL GLASS

Recent Developments in Optical Glass Manufacture

THE demand for particular types of optical glass has changed considerably during the post-War period, largely under the influence of the remarkable development of the modern photographic lens, which has been based on the production of the more extreme types of glass, notably the barium crowns.

Durability of Optical Glass

IT is the custom of optical glass manufacturers to issue long lists of types characterised by their optical constants, without much regard to their qualities of durability, which are only occasionally indicated. To the practical computer these lengthy lists are not imposing. Experience has taught him that the number of sufficiently trustworthy types is really very limited, and that only in exceptional circumstances, that fortunately do not frequently arise, may an extension of his list be justified. But while the possibility remains that glass of an unstable kind may be used in the construction of his instruments, the optician has cause for anxiety in the knowledge that his reputation as well as the glass may become tarnished.

The manufacture of optical glass

The history of the manufacture of Optical Glass can be divided into four epochs, Guinand's discovery of the stirring process in 1796, the work of Abbe and Schott circa 1882, and the development in England during the Great War being the outstanding features in this history. The method of manufacture is practically the same at the present time as in Guinand's day, any improvement being one of degree rather than of kind. Thus the glass is melted in special pots and furnaces, stirred after founding, and allowed to cool in situ. When cold it is broken up and examined. Defective glass is rejected, and the good glass is moulded into slabs, prisms or lenses, and finally annealed. Optical glass has to conform to a rigorous specification. It must have certain specified optical constants, must be free from striae, bubble, strain, and colour, and must be durable. The manufacture of optical glass is based upon continuous research into the properties of glass. The effects of composition upon density, refractive index, melting properties, durability, freedom from colour, and devitrification tendencies, have to be studied upon a small scale, and the results translated into terms suitable for works practice. The whole manufacture indeed is research upon a manufacturing scale.

The Development of Optical Industries

IN NATURE of October 20, p. 238, Messrs. Zeiss's publicity manager questions a particular period of British supremacy in the manufacture of optical glass, and in doing so he minifies the value of Faraday and Harcourt's work. Of Harcourt he says:“The result at that time (between 1834 and 1844) was scarcely of any practical importance.”