A laser metrology/viewing system for ITER in-vessel inspection1

This paper identifies the requirements for the International Thermonuclear Experimental Reactor metrology and viewing system, and describes a remotely operated precision surface mapping system. A metrology system capable of achieving sub-millimeter accuracy must operate in a reactor vessel that has high gamma radiation, high vacuum, elevated temperature, and magnetic field. A coherent, frequency modulated laser radar system is under development to meet these requirements. The metrology/viewing sensor consists of a compact laser optics module linked through fiber optics to the laser source and imaging units, located outside the harsh environment. The deployment mechanism is a remotely operated telescopic-mast. Gamma irradiation to 107 Gy was conducted on critical sensor components at Oak Ridge National Laboratory, with no significant impact to data transmission, and analysis indicates that critical sensor components can operate in a magnetic field with certain design modifications. Plans for testing key components in a magnetic field are underway.