Precise diagnostics for SG-II facility

Diagnostics is important for large laser facilities to monitoring laser status and to analyzing physics phenomena on target. SG-II facility in Shanghai is setup in 2001 with eight beams. Each beam's energy is 300J at 351nm, and its pulse width is 1ns. SG-II ninth beam is setup in 2005, its energy is 2700J at 351nm, and its pulse width is 1ns too. In recent years, it is an important international user facility for laser research with precise diagnostics system. With the development of SG-II, a new calorimeter is designed to 400 × 400mm² in order to measure absolute energy up to 6400J at 351nm. Fast photodiode and 12GHz oscilloscope is used to analyze nanosecond pulse shape. In order to analyze petawatt laser pulse, a single shot auto-correlator is designed to measure pulse width between 0.5∼18ps. And pulse contrast is obtained by a cross-correlation with fiber-array, which dynamic range is ∼10⁶ when pulse is 1mJ and 10ps. Quality of far-field measurement is 1.1DL for nanosecond pulse,and that is 1.5DL for picosecond pulse. (paper)