METHOD AND DEVICE FOR MEASURING ELECTROMAGNETIC WAVES EMANATING FROM A MELT

The method of measuring electromagnetic waves emanating from the interior of a melt (3), in particular metal melt, involves blowing gas into the melt (3) to form a gas-filled cavity (26) and observation and evaluation of the electromagnetic waves emitted by the melt (3) through the inblown gas by directing the electromagnetic waves via an optical system (20) to a detector (22) for determining temperature and/or chemical composition. To eliminate spurious measurements, the emitted electromagnetic waves are separated from electromagnetic waves (36, 37, 39, 40) aligned obliquely relative to the optical axis (38) of the optical system (20) and present outside a boundary radius (41) drawn from that optical axis (38). This is done by: deviating these electromagnetic waves from the optical axis (38) in a wave scattering device (42) of the optical system (20) so that only electromagnetic waves aligned more or less parallel to the optical axis (38) of the optical system (20) reach a detector (22) located downstream of the optical system (20); and/or by displacing the optical system (20) and aligning the optical axis (38) of said system relative to the cavity (26) until the intensity of the emitted electromagnetic waves when evaluated reaches a maximum value.