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By the present time RF-excited waveguide CO2 lasers have become widely spread and are applied in various fields of science and technology. High specific energy characteristics, small size and resistance to climatic and mechanic effects, possibility of continuous tuning of the emission frequency make their use in infra-optical communication and location systems, in systems of remote control of environmental pollution and in precision measuring systems highly promising. The above applications put high demands to spatial characteristics of the emission of waveguide CO2) lasers; they require radiation pattern axis stability, uniformity and stability of field distribution over the cross sections of the beam both in the near and far zones. Besides appearance of additional spectral components in the range of emission frequencies is unacceptable in systems using heterdyne information processing. However, in some experimental works and in attempts to introduce these devices into actually operating apparatus some cases of deformation of spatial characteristics of radiation from sample to sample were notd in the course of operation, as well as the so-called whistle of transverse modes even with visually uniform transverse distribution in the radiation spot. In the light of the above there is continuous attention and interest to investigation of spatial and time response of the emission spectrum of RF-excited waveguide CO2 lasers.
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