Measuring apparatus and method for measuring the temperature of a molten metal bath with an optical device

Measuring apparatus for measuring a temperature of a molten metal bath, comprising

• i) an optical device,
• ii) a detecting means,
• iii) a storing unit for the optical device,
• iv) a rotatable support for the storing unit for the optical device,
• v) a moving means,
• vi) a straightening means,
• vii) a housing and
• viii) a guiding system connected to the housing,
• wherein the optical device comprises an optical fiber laterally surrounded by an inner and an outer metal tube,
• wherein the outer metal tube has an outer diameter of in the range of 2 mm to 8 mm and a wall-thickness in the range of 0.1 mm to 0.6 mm,
• wherein the housing encloses the detecting means, the storing unit for the optical device, the rotatable support for the storing unit for the optical device, the moving means, and the straightening means and
• wherein the moving means is adapted to feed and retract the optical device and comprises
• a) at least one motor for forward and backward driving the rotatable support for the storing unit for the optical device,
• b) a feeding means for feeding the optical device driven by at least one motor for forward and backward driving.