Page 315 - Instrumentation Reference Book 3E
P. 315
Temperature measurement considerations 299
However, in this section we are interested in compounds. Cholesteric liquids are extremely
those liquid crystalline compounds that respond optically active as a consequence of their forming
primarily to temperature. The compounds a helical structure. The niolecules have a largely
involved are a group of compounds derived from flat form and as a result lie in a laminar arrange-
or with molecular structures similar to choles- ment.. However; the molecules have side groups
terol. They are therefore called cholesteric which prevent them lying on top of one another
+
Incident ray of light
I
D i rect ion of polarization
J
Ai ignrnent
of molecules
-c Emergent ray
Figure 14.68 Rotation of the plane of polarization of light by liquid crystal.
