Quasi-optical interferometers with enhanced phase sensitivity

MW interferometers are widely used for the investigation of a plasma. These interferometers permit determining electron density by the measurement of the phase shift of a wave probing of the plasma relative to the wave passing over the free space. In case of measurement of a small phase shift, the high phase sensitivity and small phase noise of interferometers are required, the phase sensitivity is meant as the ratio between the phase shift of a probing wave and the change of electron density which caused it. One of methods of increasing the phase sensitivity of interferometers is a multiple transition of probing radiation across the plasma. For this purpose in the submillimeter wavelength range it is expedient to apply a hollow dielectric waveguide as a quasi-optical waveguide structure and radiomeasuring quasi-optical devices. The scheme of a reflecting type quasi-optical interferometer, that provides the quadruple transition of a wave across plasma, is presented.