Characteristics of striæ in optical glass . Fig. 12.—Rolled window plate of Fig. 10 viewed at an angle 0/45° The images {h, c) seen through the flat of the window plate arevery little inferior to those obtained with a clear aperture, whereasthe images (d, e, f), viewed through the polished edges, are blurredon accotint of the pronounced scattering of the light. That dense striae are seriously injurious to definition is thenevident. However, there are many good lenses which contain a. Fig. 13.—Rolled crown glass viewed edgewise few isolated striae, and a few isolated striae do very little damag
Characteristics of striæ in optical glass . Fig. 12.—Rolled window plate of Fig. 10 viewed at an angle 0/45° The images {h, c) seen through the flat of the window plate arevery little inferior to those obtained with a clear aperture, whereasthe images (d, e, f), viewed through the polished edges, are blurredon accotint of the pronounced scattering of the light. That dense striae are seriously injurious to definition is thenevident. However, there are many good lenses which contain a. Fig. 13.—Rolled crown glass viewed edgewise few isolated striae, and a few isolated striae do very little much is this true that an examination of a large number ofrejected binoculars at this Biu-eau showed no certain connectionbetween the presence of striae and faults of definition. Thestriae in a large, high-grade photographic lens are shown in Fig. 16,and the striae in a telescopic lens with an aperture of about 5 84 Scientific Papers of the Bureau of Standards [Vol. i6 inches and a focal length of about 20 inches are shown in Fig. lens was made from Bureau glass and finished by JohnClacey in the optical shop. The definition and performance areexcellent. That the presence of even a considerable amount of not tooheavy striae is not greatly injurious to the definition in ordinary
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Keywords: ., bookcentury1900, bookdecade1920, bookidcharacterist, bookyear1920
