Intense Laser Complex Ray Machine Component Optical Elements Laser Damage Detection Technology

Experiment in inertial confinement fusion(ICF) required very strict condition on output ability,beam quality,load capacity and controll ability.In order to achieve the condition in fusion,the energy on target must exceed 1MJ.At the 351nm wavelengh,it was believed that the laser-induced damage threshold of optics is lowed,putting the optics in 351nm of the laser at higher risker to laser-induced damage.With the laser fluence up to 3J/cm2,after few high fluence shots,as a key component,Located at the target chamber,the integrated optics module(IOM) is easy to be damaged.Laser-induced damage of large aperture optics would decrease the optics lifetime,such as KDP cristial,fused cilica lens and sampling grating.et.al,and has been the main limter of imprived the load capacity of laser facility.The management stratege of optics requires the worked to put more attention on optics quality,as well as the management of each process. High-powerlaser-induced material damage is a self-accelerating process. With the subsequent laser shots, the initial damage on the optics will gradually growth. In order to aviod the disaste damage in follow-up shots, the surface damage of optics was be inspected by the online optics damage inspection,when the flaw has grown to the maxmum allowed size,the optics will be replaced and sent to the damage mitigation and repaired. FODI is the base of the safe management stategy of optics. As the construction of the SG-III facity, the demand for final optics damage inspection is increasingly urgent. On-line damage inspection system and key technology research are also urgent, which are the problems need to sovle that research faced now. Based on the above requirement this paper research the final optical damage inspection and key technologies in-depth and the following technological advances have made:Firstly, Proper illumination of the optic to be imaged is critical for the successful performance of the FODI system, Two imaging methods will be employed to illuminate the optics, bright-field back illumination and edge illumination. The first time systematically studied the online damage inspection problem in large, high-power final optics, a roadmap of total internal reflection illumination dark-field imaging technology is presented to achieve online high-resolution damage image of final optics. In order to solve the problem that it is difficult to distinguish the damage from two adjacents optics due to the shallow depth of imaging field, the method of time- sharing illumination of large aperture optics was developed for damage imaging, and the model of signal noise ratio was developed for dark field imgeing mode.Second, the study of techniques for damage imaging to the integrated optics module(IOM),high resolution and many dimensions scanning.The engineering proposal of optics and was develped for IOM damage inspection.Third, proper illumination of the optic is critical for the successful performance of the IOM optics damage inspection, based on total internal reflection, the two edge illumination method was proposed to illuminate the optics, linear array LED light source and fiber laser,and studied to verify the implementation of large aperture optics uniform illumination.Final the parameter of illumination was optimized. It was demonstrated the method of optical components illumination from the corners with the fiber laser to achieve total internal reflection uniform illumination within the full-aperture.Fourth, studed on the image analysis of damage.A modified Local Area Signal-to-Noise Ratio (LASNR) segmentation algorithm was developed to capture signal in the image at every pixel within an object versus the noise in its local neighborhood.With a character method of information, the character extraction and characterization is efficency achieved for data minning.Based on classify and machine learning, the method of data analysis and damage evaluation is proposed. a radiation calibration method is proposed. By increasing the exposure time, a slight damage point can be detected online. Calibration of radiation can solve the problem of point tracking and inspection of very small damage when the CCD pixel object resolution is more than the size of flaw.Fifth, the first time in the country designed and developed a high resolution IOM1 optics damage inspection system (FODI). The integaration experimental was carried out to test the technical proposal and key techniques for FODI. The results show that this technique is feasible for lare aperture optics online damage inspection.