BARTOL RESEARCH
WHEN light of a given frequency v is FOVNDATION passed through a dielectric, transparent to Communication ~o. 33. that frequency, which forms part of a parallel plate condenser, the light wave can be changed in character in two ways when electromagnetic waves of frequency P are impressed on the condenser.
First, the light, if it is initially plane polarized, will become elliptically polarized due to the medium becoming double refracting. If the frequency P of the electromagnetic waves is such that the medium has an absorption band at this frequency, then the double refraction will be considerable, or in other words, the Kerr constant will be abnormally large.
Second, the light train will be modulated, i.e., besides the original frequency ~, there will appear light trains of frequencies u +P, u + 2P, ... and u -P, u -2P, .-. etc. If the medium does not become double refracting, then the amplitudes of the modulated wave trains would be the same for corresponding frequencies, i.e., the amplitude of the light train of frequency u-nP would be the same as that of frequency u + nP, so that the energy would be equally distributed towards the long and short wave-length side of the original line. When, however, account is taken of the double refraction of the medium, the energy will be no longer equally distributed among the modulated wave trains towards the long and the short wave-length side of the line, but there will be a greater amount of energy divided among the modulated waves on the long wave-length side of the line than towards the.' other side.
In these experiments, the light of an iron arc which passed through a Kerr cell containing water was photographed with a quartz spectrograph; the lines in the region from 2480 to 2500 A. were examined with a microphotometer. It was found 3~5