The effects of sinusoidal electric fields on various DNA samples are characterized by parallel recording of the "enforcing" electric field and of the resulting dichroism effects; these data are then evaluated quantitatively by a deconvolution technique. The linear dichroism of a restriction fragment with 256 base pairs under sinusoidal electric fields shows the effects expected from rotational diffusion of an induced dipole with a short polarization time constant : a dispersion of the optical sine amplitude and of the phase difference in the frequency range around 20 kHz, but no dispersion of the average stationary value of the negative dichroism. The experimental data can be described with high accuracy as a convolution product of the squared forcing function with a single relaxation process over a broad range of frequencies. Measurements with plasmid DNA’s of various chain lengths reveal that both the sine amplitude and the average stationary amplitude of the negative dichroism effect almost disappear at high frequencies; the data show a distribution of time constants; both mean value and width of the distribution increase with the chain length. The dispersion data for the long DNA molecules are attributed to a dipole resulting mainly from field induced deformation of the polymer spheres. The deconvolution procedure is applied also for analysis of reverse pulse experiments. The dichroism induced by a reverse pulse in a solution of a 256 bp restriction fragment can be fitted with high accuracy by a single time constant reflecting overall rotational diffusion. This experiment demonstrates a high rate of polarization and the absence of any substantial contribution to the orientation from a permanent moment. In general, the deconvolution procedure for analysis of electrooptical data obtained in the frequency domain proves to be superior to conventional procedures, because the required information, which used to be extracted from frequency dependences of stationary amplitudes, sine amplitudes, or phases, is obtained in a single step; furthermore, transients, which are observed at the start or the end of enforcing wavetrains and contain valuable information, may be included in the analysis without problems.