The paper is organized as follows: in Section 2 we determine the electrooptic crystal classes that are suitable for measuring the path integral of the electric field.
An analysis of the electrooptic (i.e., non-centrosymmetric) crystal classes yields several classes that meet the conditions for a path integration of the field [22,23]; that is, only the field component parallel to the optical path in Figure 1 shall cause an electrooptic phase shift whereas transverse components shall leave the phase difference unaffected.
Note that symmetry properties of the piezoelectric effect in certain crystal classes can also be employed to measure the path integral of the electric field with an optical sensor [24, 25].
Crystallographic Principles covers the following: (1) Crystal Systems; (2) Crystal Classes
, Point Group Symmetry, and Symmetry Notations; [There is no section 3)]; (4) Miller Indices and Zone Symbols; (5) Crystal Forms; (6) Space Groups; (7) Choice of Settings; and (8) Twinning and Epitaxy.