Up to now, no model or contactless sensor has been available foron-line control of the effectiveness of the flow of the stirring gas inthe ladle in secondary metallurgy. A new method, based on the useof conoscopic holography, has been developed by Arcelor-Aceralia.It measures on line the vibrations in the walls of the ladle and relatesthem to the argon flow rate. This method is useful for determiningthe real state of the stirring process, obtaining an accurate index ofthe process of melt agitation that influences the composition homogeneityand cleanliness.