The contamination on optical surface is an important factor that causes laser-induced damage. In the assembly process of the SGIII, the traditional manual assembly method poses a great challenge in terms of the cleanliness of optical components. So the contamination introduced by the manual assembly is studied including particulate and non-volatile residue (NVR). The use of vacuum system device to clamp is an important means to achieve automated clean assembly. The contact contamination is the main source of contaminants in the vacuum-clamping process. One source is the organic residue left on the optical surface, by comparing the residue of different sealing rubber after absorbing the optics, we find that FPM (fluorine rubber) brings the least contamination. The second source is the coating debris causing by the compressive and shear stress on the optical surface during the vacuum clamping process. We have established a theoretical model, through the numerical simulation method to obtain the stress under different assembly conditions. For different optical films, the stress during the assembly process cannot exceed the fatigue limit of the optical coating to prevent the film from being destroyed and debris contamination. The cleanliness level of the vacuum clamp assembly process is evaluated through experiments. The results show that the contamination generated by assembling large-aperture optics with a vacuum gripper meets the optical surface cleanliness requirements.
KDP frequency converters are the important components applied in the final optics assembly for Inertial Confinement Fusion device. And the efficiency of second harmonic generation is much affected by phase matching error, which is induced by surface distortion. In this paper, focusing on the surface distortion under the specific mounting process of KDP frequency converters, we proposed an effective prediction method based on modified mechanical model to accurately predict the surface distortion during assembly. Using numerical simulation, we analyze the key elements that influence the surface distortion so as to adjust the mounting process according to the results. Results and findings in this article are meaningful for improving mounting-induced surface distortion of KDP frequency converters. Moreover, the mechanical model and prediction method presented will offer more efficient and reliable technical proposal for next generation ICF facility
Surface control and phase matching of large laser conversion optics are urgent requirements and huge challenges in high-power solid-state laser facilities. A self-adaptive, nanocompensating mounting configuration of a large aperture potassium dihydrogen phosphate (KDP) frequency doubler is proposed based on a lever-type surface correction mechanism. A mechanical, numerical, and optical model is developed and employed to evaluate comprehensive performance of this mounting method. The results validate the method’s advantages of surface adjustment and phase matching improvement. In addition, the optimal value of the modulation force is figured out through a series of simulations and calculations.
In the high power solid laser driver, the frequency conversion unit is of strict requirement to meet the drive condition of ICF. The performance of large caliber KDP crystal, which is the core of frequency conversion of laser, is a vital aspect affecting the overall technical index of the laser driver. In order to get a higher efficiency of frequency conversion, KDP crystal must keep a better surface condition, which asks for high-quality assemblage and adjustment. The current method used in engineering has insufficient knowledge and recognition on surface deformation control of the crystal. Meanwhile, the method itself is of low efficiency on clamping, and lacks of protection for the crystal. Thus, in this article an investigation of crystal clamping method with lower force was performed, factors affecting the surface of crystal were explored, through both imitation and experiment. The clamping method was redesigned and the frequency conversion efficiency was tested. Meanwhile, with the new method, clamping efficiency increases, the optical performance of crystals improves, and the crystals get better protection.
High-energy solid-state laser is an important way to achieve laser fusion research. Laser fusion facility includes thousands of various types of large aperture optics. These large aperture optics should be assembled with high precision and high efficiency. Currently, however, the assembly of large aperture optics is by man’s hand which is in low level of efficiency and labor-intensive. Here, according to the characteristics of the assembly of large aperture optics, we designed three kinds of grasping devices. Using Finite Element Method, we simulated the impact of the grasping device on the PV value and the RMS value of the large aperture optics. The structural strength of the grasping device’s key part was analyzed. An experiment was performed to illustrate the reliability and precision of the grasping device. We anticipate that the grasping device would complete the assembly of large aperture optics precisely and efficiently.