Fundamentals of the theory of spectral instruments and their devices, as well as the technique of spectroscopic experiment in the study of the visible and close ultraviolet regions of the spectrum. In addition to prism and diffraction spectral devices, light sources, methods of energy measurements and measurement of wavelengths, methods and devices of interference spectroscopy, methods for studying abnormal dispersion and atomic absorption spectra are described. A separate chapter is devoted to laser spectroscopy.