Abstract
A fiber-optic long-base deformometer has been developed, which can be used in rock monitoring systems for open pit walls. The proposed deformometer is based on the method of controlling the additional losses of a light wave propagating in an optical fiber. The fiber optic sensor has a fairly high linearity and stability of the output signal, and is also not subject to the negative occurrence of fading inherent in fiber optic sensors based on the Mach-Zehnder interferometer, with fluctuations in ambient temperature and the appearance of false signals about the displacement of rocks.