ITER perspective on fusion reactor diagnostics - A spectroscopic view

The ITER tokamak requires diagnostics that on the one hand have a high sensitivity, high spatial and temporal resolution and a high dynamic range, while on the other hand are robust enough to survive in a harsh environment. In recent years significant progress has been made in addressing critical challenges to the development of spectroscopic (but also other) diagnostics. This contribution presents an overview of recent achievements in 4 topical areas: - First mirror protection and cleaning - Nuclear confinement - Radiation mitigation strategy for optical and electronic components - Calibration strategie