The influence of absorption on spectral characteristics of hard ondulator radiation

A formula describing the frequency-angular distribution of ondulator raiation in an absorbing medium is obtained. The spectral characteristics of hard ondulator radiation depending on the absorbability of medium are invesigated in dipole approximation. It is shown that irrespective of the absorbability of the medium, the growth of maxima of the angular distribution of intensity with the increase in the radiation frequency is accompanied by broadening of spectra. It is also shown that consideration of absorption leads to essential variation of radiation spectra