FIELD: physics.
SUBSTANCE: method comprises the following steps: moving a coated steel band on an arched path on the outer surface (813) of a drum (8) revolving about an axis (51), having a cylindrical wall guiding the band, directing an ablation laser beam inside the cylindrical wall such that its optical incidence occurs on the axis of the normal (41) to the outer surface of the drum at a target point (11) of contact of the band and the drum, passing the beam through the wall through an opening (811) on the wall which is transparent for the beam. Plasma spectral radiation from the laser ablation at the point of contact is collected through optical reflection towards the axis of the normal (41) to the outer surface of the drum and through the opening, after which it is directed into a spectral measurement unit. The axis of the normal (41) to the outer surface which corresponds to optical incidence and reflection is rotated synchronously with the drum.
EFFECT: enabling measurement during spectral analysis of a layer of metal coating deposited on the surface of a steel band which is in motion and has different formats and different speeds.
15 cl, 8 dwg
