In a method of spatially detecting the chemical composition of nonmetallic components on a surface which is subsequently to be coated with a metallic and/or ceramic and/or organic layer, a laser optical device is provided. The turbine part is irradiated with monochromatic irradiation at a first wavelength (λin) with the laser optical device. Radiation is detected which is emitted by the surface at a second wavelength (λout) which is longer than the first wavelength (λin).