Electric Fields Produced by a Charge Density in Ionic Crystals.

Spatially extended defects such as the center give rise to an effective defect charge density which may produce important polarizations in the crystal. The electric field in the crystal depends upon these induced dipoles. Lattice summations for the contribution to the electric field which arises from ionic shells centered about the defect are evaluated for the NaCl and CaF lattice structures.

Electrostatic Potentials and Their Spatial Derivatives About Point Defects in Ionic Crystals.

The electrostatic potential which arises from a lattice array of point ions is computed in terms of a Taylor's series expansion for small distances from a lattice site. This expansion gives the change in electrostatic energy when an ion moves in the background of a perfect point ion lattice potential. The Taylor's series coefficients for terms up to fourth order in the ion displacement are evaluated for the NaCl and CaF lattice structures.

Accurate method for determining photometric linearity.

Accurate photometric measurements depend on the linearity of the detection system, i.e., whether the output is strictly proportional to the incident light flux.