Improvement of the Measurement Accuracy for the Fabry–Perot Interferometer Length in Systems with Spectral Encoding of Broadband Radiation

A simple method is proposed for taking into account diffraction of the beam in the Fabry–Perot fiber-optic interferometer used in measuring systems with spectral encoding of broadband radiation. The method is based on linearization of the dependence of the phase difference on the optical frequency in the working range. A diffraction correction to the measured interferometer length is obtained, which is on the order of tens of nanometers. The result of the work can be used in systems for measurement of nanodisplacements, temperature, pressure, and other physical quantities.