Interferometric system for detecting radiation wavelength shift

Interferometric system for detecting radiation wavelength shift functions based on a Fabry-Perot interferometer. Means developed for enhancing the system performance are described, namely: a method of increasing illumination of detected fringes for enhancing the system sensitivity, and a method of compensating interference maxima spreading caused by misalignment of mirrors that allows enhancing accuracy of light frequency shift measurement. The way to increase detected fringe brightness is based on additional reduction of the divergence of passing through the interferometer light beam. This method allows compensating negative effect of collimating lens spherical aberrations, and, using them, increasing the detector illumination. The way of compensating the interferometer mirrors misalignment effect on the detected fringe is based on use of specific relative position of beams from various parts of the interferometer near the focal plane of the focusing lens.