509 

 TABLES 522-555.— OPTICAL GLASS AND OPTICAL CRYSTALS 



Optical glass and optical crystals are in general described by giving their 

 indices of refraction for standard wavelengths, such as the D, A, C, F, 

 etc., lines and their v values = (n D — l)/(n F — n c ). Also, the spectral trans- 

 mission and some other physical constants may be given. In addition, many 

 crystals have different optical properties in different directions which require 

 some consideration of their optical axes. For glasses used as niters the spectral 

 transmission is an important item. A table of wavelength units and some data 

 on various types of optical glass and crystals follow. 



Radio 

 meter 



TABLE 522.— RADIATION WAVELENGTH UNITS 



Radiation 

 micron 



Colorimetry 

 millimicron 



Spectroscopy 

 angstrom 



X-rays y rays 



X-ray units microangstrom 



Powers-of-10 equivalent of units listed in column 1 



Units 



Name Symbol ii 



Micron n 1 



Millimicron mfi 10~ 3 



Angstrom A 10~ 4 



X-ray unit Xfi 10~ 7 



Microangstrom p.A 10~ 10 



m/j. 



IO 3 



1 

 io- 1 



lO" 4 



io- 7 



A 



io 4 



10 



1 



io- ! 

 io- ( 



xu 

 IO 7 

 10 4 

 10 3 



1 

 io- a 



HA 



IO 10 



10 7 



io 6 

 io 3 



1 



cgs 

 unit 

 cm 



IO" 4 

 IO" 7 



io- 8 



IO 11 

 IO" 14 



mm 



10" 3 

 IO" 9 



io- 7 

 io- 10 

 io- 13 



10" 

 10" 



io- 

 io- 



10" 



The X-ray unit as originally used referred to the measurement of x-wavelengths using a 

 calcite crystal. Such results are in error by a factor of 1.00203. 



OPTICAL GLASS 

 TABLE 523.— CHARACTERISTICS OF AMERICAN-MADE OPTICAL GLASSES 160 



Crown glasses — crown (CO), light barium crown (LBC), dense barium crown (DBC), 

 extra dense barium crown (EDBC) 



Name C —BL LBC —BL DBC —CG DBC —CG DBC —CG EDBC —BL 



Type 518/596 573/568 612/595 620/603 638/555 617/539 



n D 1.51780 1.57250 1.61160 1.62030 1.63840 1.61700 



n G ' 1.52886 1.58538 1.6246 1.6332 1.6532 1.63171 



n r 1.52393 1.57962 1.61880 1.62750 1.64650 1.62511 



n c 1.51524 1.56954 1.60852 1.61722 1.63500 1.61367 



v 59.6 56.8 59.5 60.3 55.5 53.9 



Flint glasses— crown flint (CF), light flint (LF), short flint (SF), extra light flint (ELF), 

 light barium flint (LBF), barium flint (BF), dense barium flint (DBF), 

 dense flint (DF), extra dense flint (EDF) 



Name CF —BL LBF —BL BF —BL DBF —BL DBF —CG ELF —BL 



Type 526/546 548/537 570/481 617/385 670/472 541/475 



n D 1.52560 1.54770 1.57040 1.61700 1.66990 1.54140 



no' 1.53793 1.56081 1.58575 1.63811 1.6882 1.55618 



n F 1.53239 1.55491 1.57880 1.62843 1.67990 1.54949 



n c 1.52277 1.54471 1.56695 1.61242 1.66572 1.53809 



v 54.6 53.7 48.1 38.5 47.2 47.5 



Name ELF —BL SF —CG LF —BL DF —BL EDF —BL 



Type 559/455 613/442 575/429 596/397 751/277 



n D 1.55850 1.61300 1.57510 1.59560 1.75060 



no' 1.57447 1.6308 1.59263 1.61538 1.78716 



ti F 1.56722 1.62280 1.58464 1.60632 1.77009 



n c 1.55495 1.60893 1.57122 1.59130 1.74302 



v 45.5 44.2 42.9 39.7 27.7 



160 Adapted from data from Bausch & Lomb (BL) and Corning Glass Works (CG). F. A. Molby, 

 West Virginia University, assisted in selecting and arranging these data. For reference see Molby, 

 Journ. Opt. Soc. Amer., vol. 59, p. 600, 1949. 



SMITHSONIAN PHYSICAL TABLES 



