The intensity of spectral lines Al I 309.4 nm, Al II 358.7 nm, Mg II 279.6 nm, Ti II 323.6 nm of the main clay components were studied depending on the position of a sample with respect to the focus of the optical system, when the samples are exposed to radiation of the Nd3+ :YAG laser operating in a single-pulse mode. The allowable intervals of positioning the sample relative to the focus of the optical system (positive and negative defocusing) are determined, at which the reproducibility of the intensity values of the spectral lines of the samples of red and white clay do not practically change. It is shown that the position of the sample relative to the focus of the optical system should lie in the interval ΔZ ~ ±1.5 mm at the optimum laser pulse energies for the spectral lines under study. The radiation flux density for various laser pulse energies and distances from the focus to the sample has been calculated. It has been experimentally shown that the reduction of the radiation flux density leads to a decrease in the intensity of the analyzed spectral lines.