metallurgical vessel and process for the manufacture of a container wall

Container metallurgical with a gap to treat a first liquid or liquefying metal metal space, wherein the container comprises a coolable wall (1) with a hot side facing the hollow space and a cold side remote hollow space of a second metal and wherein the wall (1) is equipped in the area of ​​the hot side with waveguides light (5, 6, 7) arranged near the surface for detecting data of the metallurgical vessel or the first metal, wherein the waveguide light (5, 6, 7) are inserted into grooves (2, 3, 4; 28), which are performed from the hot side to the wall (1) and slots (2, 3, 4; 28) are closed with the waveguides of light introduced through filler piece (8, 9, 10; 27) on the hot side, characterized in that the grooves (2, 3, 4; 28) have a cross section that tapers towards its groove bottom (25).