
97-6 Displays and Recorders
Figure 97.6a and b shows the temperature dependence [2] and wavelength dependence [2] of the refrac-
tive
in
dices
of ty
pical
LC ma
terials
. e de
pendence
of re
fractive
in
dex
on wa
velength
λ is ge
nerally
ex
pressed
b
y
t
he
s
o-called
C
auchy
e
quation:
n n
o,e
o,e
= +
∞
α
λ
2
(97.5)
where
n
∞
is the refractive index extrapolated to innite wavelength
α
i
s
a m
aterial-specic
c
oecient
97.3.3 Elastic Constants
In uniaxial LCs, the preferred or equilibrium orientation of the LC molecule is given by the director
n, which may be imposed by the surface treatments at the boundary conditions or by an external eld.
400
1.4
1.6
1.8
500 600 700
30