
16 OPTICS FOR ENGINEERS
Refractive index n
d
2.1
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
100
BeF
2
FB
FA
FP
FK
PK
PSK
SSK
BaK
BaLF
KzFS
BaF
BaSF
TISF
SF
SFS
LaF
LaSF
Chalcogenides
LaSK
LaK
TaSF
TaF
NbF
SK
BK
K
KF
LLF
TIK
TIF
LF
F
SiO
2
FZ
80 60
Abbe number n
d
40 20
Figure 1.7 A glass map. Different optical materials are plotted on the glass map to indicate
dispersion. A high Abbe number indicates low dispersion. Glasses with Abbe number above 50
are called crown glasses and those with lower Abbe numbers are called flints. (Reprinted from
Weber, J., CRC Handbook of Laser Science and Technology, Supplement 2, CRC Press, Boca
Raton, FL, 1995. With permission.)
where the indices of refraction are
n
d
at λ
d
= 587.6 ...