Characteristics of striæ in optical glass . PRICE 5 CENTS Sold only by the Superintendent of Docvunents, Government Printing Office Washington, D. C. WASHINGTON GOVERNMENT PRINTING OFFICE 1920 CHARACTERISTICS OF STRI/E IN OPTICAL GLASS By T. T. Smith, A. H. Bennett, andG. E. Merritt CONTENTS Page I. Appearance and effects of striae 75 1. Detection of striae 76 2. Projection of striae 78 3. Characteristic striae 81 4. Striae and definition 82 II. Index of refraction 87 III. Summary and conclusions 91 I. APPEARANCE AND EFFECTS OF STRI^ In the manufacture of optical glass one of the difficult req
Characteristics of striæ in optical glass . PRICE 5 CENTS Sold only by the Superintendent of Docvunents, Government Printing Office Washington, D. C. WASHINGTON GOVERNMENT PRINTING OFFICE 1920 CHARACTERISTICS OF STRI/E IN OPTICAL GLASS By T. T. Smith, A. H. Bennett, andG. E. Merritt CONTENTS Page I. Appearance and effects of striae 75 1. Detection of striae 76 2. Projection of striae 78 3. Characteristic striae 81 4. Striae and definition 82 II. Index of refraction 87 III. Summary and conclusions 91 I. APPEARANCE AND EFFECTS OF STRI^ In the manufacture of optical glass one of the difficult require-ments, perhaps the most difficult that the manufacturer hasto meet, is that the glass shall be homogeneous. Glass which. Fig. I.—Shadowgraph of heavy stricB has been melted and stirred with the utmost care will containbubbles and striae. The latter, sometimes called *cords orveins, consist usually of threads or sheets of material of whichthe refractive index is a little different from that of the surround-ing glass. There results from this difference in index an irregu-larity in the wave front of the light traveling through the the irregularities are sufficiently great for a casualglance to reveal that there are striae in the glass, but with opticalglass that has passed the first rough inspection a rather carefulexamination is needed to detect their presence. Figs, i and 2 75 76 Scientific Papers of the Bureau of Standards [voi. i6 are photographs showing the appearance, much accentuated, ofseveral gradations of striae in slabs picked for the purpose. Bothplates of Fig. i possess heavy striae which would be observedat a casual glance even by an unpracticed eye. The striae ofthe plates
Size: 2318px × 1078px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookidcharacterist, bookyear1920
