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The results of investigations into the dynamics of the light-induced absorption and of its dark relaxation in a Bi12TiO20 : Ca single crystal are presented. To illuminate the crystal and to measure the induced changes in the absorption, narrow-band radiation of an incoherent semiconductor light-emitting diode with the wavelength λ = 660 nm close to that of a helium-neon laser was used. The material parameters of the crystal are estimated based on a comparison of the experimental data with the results of calculations for a theoretical model that takes into consideration doubly ionized donor centers and shallow traps.