ICF laser target alignment sensor calibration system

Laser Target Alignment Sensor (LTAS) focus high energy laser beams on the sub-centimeter size fusion targets at the precise location and adjusts the final focus lenses to set the spots size in Initial Control Fusion (ICF) experiment. The operational requirements of the ICF system place tight constraints upon the precision of the LTAS. Therefore, a calibration system which can adjust conjugation distance of the LTAS, compensate the location of the beam spots, and calculate the axis and magnification of the objectives is designed. The system is composed of a long focal-length telemicroscope, a high resolution CCD, a NC dividing head, an X-Y linear stage, a multidimensional target positioner and two simulated laser beam generators. Feedbacks based on the LTAS images of the target and laser points are used to null offsets of the LTAS on conjugation distance. The methods of objective and CCD parameter calibration are presented. Experiments for the positioning accuracy test show that after calibration, the repeatability error of the LTAS for the target center location is better than +/- 0.7 mu m. The system can realize accurate calibration of the LTAS before putting it into target chamber, which will improve the precision of ICF experiments effectively.