By testing a substantial number of tripler and z-cut KDP and DKDP crystals, we have observed that at 355nm, the laser induced damage threshold in the R-on-one test is higher than that in the one-on-one test. It is pro...By testing a substantial number of tripler and z-cut KDP and DKDP crystals, we have observed that at 355nm, the laser induced damage threshold in the R-on-one test is higher than that in the one-on-one test. It is proved that laser conditioning is an efficient way to improve the damage resistance. The efficiency of laser conditioning becomes increasingly good with smaller ramping fluence steps. We have also found that the damage resistance of the z-cut crystal is higher than the triplet cut, and the pinpoint number is definitely less in the z-cut crystal. The reason for these observations is discussed.展开更多
Wet etch process is applied to expose the bulk damage sites in KDP crystals to the surface for the examination by scanning electron microscopy(SEM)and optical microscopy.The damage sites induced by 1064 nm laser consi...Wet etch process is applied to expose the bulk damage sites in KDP crystals to the surface for the examination by scanning electron microscopy(SEM)and optical microscopy.The damage sites induced by 1064 nm laser consist of three distinct regions:a core,an outer region of modified material,and some oriented cracks.Laser irradiated with 355 nm results in an increase of damage density,a decrease of core diameter and,rarely,occurrence of the crack.WavelengKey Laboratory of Materials for High Power Laser,Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences,Shanghai 201800th dependence of the damage feature suggests that a repulsive force exists among the adjacent plasmas,which prevents further expansion of plasma and decreases the size of plasma.The deposited energy absorbed by the smaller plasma may not be able to generate the crack.展开更多
A thermal model is considered in order to better understand the mechanism of laser induced damage in KDP and DKDP crystals. We demonstrate that the expressions of pinpoint density and damage probability, predicted by ...A thermal model is considered in order to better understand the mechanism of laser induced damage in KDP and DKDP crystals. We demonstrate that the expressions of pinpoint density and damage probability, predicted by the thermal model, are consistent with the experimental data. We also discuss the effect of particle interaction on the thermal model.展开更多
By testing the number increase and size growth of surface and bulk laser induced damage in KDP and DKDP crystals, we observe different growth characteristics of surface and bulk damage under multiple 355nm laser irrad...By testing the number increase and size growth of surface and bulk laser induced damage in KDP and DKDP crystals, we observe different growth characteristics of surface and bulk damage under multiple 355nm laser irradiations. The size of the surface damage grows exponentially, but that of the bulk damage does not grow. In contrast, the bulk damage number increases, but that of surface damage does not increase significantly. We attribute the differences to the different formation of the damage initiators and the different damage testing volumes.展开更多
The multilayer(ML)YSZ/SiO_(2) films with different modulation ratios ranging from 1:3,4:9,1:1 to 3:1(the thickness ratio of the YSZ to SiO_(2))are deposited on BK7 glass substrates by electron beam evaporation under t...The multilayer(ML)YSZ/SiO_(2) films with different modulation ratios ranging from 1:3,4:9,1:1 to 3:1(the thickness ratio of the YSZ to SiO_(2))are deposited on BK7 glass substrates by electron beam evaporation under the same processing conditions.The effect of modulation ratio on the residual stresses and structure are investigated by an optical interferometer and Grazing incidence x-ray diffraction.The results show that the total residual stress in MLs is compressive and decreases to tensile when the modulation ratio is changed from 1:3 to 3:1.The YSZ films are of cubic phase structure and the SiO_(2) films are amorphous in all the MLs.The change of residual stress in these MLs can be attributed to the variation of an individual layer?s stress with thickness,which indicates that adjusting the thickness ratio of two materials is an effective measure for depositing near-zero stress MLs.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 10676019.
文摘By testing a substantial number of tripler and z-cut KDP and DKDP crystals, we have observed that at 355nm, the laser induced damage threshold in the R-on-one test is higher than that in the one-on-one test. It is proved that laser conditioning is an efficient way to improve the damage resistance. The efficiency of laser conditioning becomes increasingly good with smaller ramping fluence steps. We have also found that the damage resistance of the z-cut crystal is higher than the triplet cut, and the pinpoint number is definitely less in the z-cut crystal. The reason for these observations is discussed.
基金Supported by the National Natural Science Foundation of China under Grant No 60878045.
文摘Wet etch process is applied to expose the bulk damage sites in KDP crystals to the surface for the examination by scanning electron microscopy(SEM)and optical microscopy.The damage sites induced by 1064 nm laser consist of three distinct regions:a core,an outer region of modified material,and some oriented cracks.Laser irradiated with 355 nm results in an increase of damage density,a decrease of core diameter and,rarely,occurrence of the crack.WavelengKey Laboratory of Materials for High Power Laser,Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences,Shanghai 201800th dependence of the damage feature suggests that a repulsive force exists among the adjacent plasmas,which prevents further expansion of plasma and decreases the size of plasma.The deposited energy absorbed by the smaller plasma may not be able to generate the crack.
基金Supported by the National Natural Science Foundation of China under Grant No 10676019.
文摘A thermal model is considered in order to better understand the mechanism of laser induced damage in KDP and DKDP crystals. We demonstrate that the expressions of pinpoint density and damage probability, predicted by the thermal model, are consistent with the experimental data. We also discuss the effect of particle interaction on the thermal model.
基金Supported by the National Natural Science Foundation of China under Grant No 10676019
文摘By testing the number increase and size growth of surface and bulk laser induced damage in KDP and DKDP crystals, we observe different growth characteristics of surface and bulk damage under multiple 355nm laser irradiations. The size of the surface damage grows exponentially, but that of the bulk damage does not grow. In contrast, the bulk damage number increases, but that of surface damage does not increase significantly. We attribute the differences to the different formation of the damage initiators and the different damage testing volumes.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10676019 and 50721002, the Program for New Century Excellent Talents in University （NCET-10-0526）, and the Natural Science Foundation of Shandong Province （ZR2009FM015）.
基金Supported by the National Natural Science Foundation of China under Grant No 10976030.
文摘The multilayer(ML)YSZ/SiO_(2) films with different modulation ratios ranging from 1:3,4:9,1:1 to 3:1(the thickness ratio of the YSZ to SiO_(2))are deposited on BK7 glass substrates by electron beam evaporation under the same processing conditions.The effect of modulation ratio on the residual stresses and structure are investigated by an optical interferometer and Grazing incidence x-ray diffraction.The results show that the total residual stress in MLs is compressive and decreases to tensile when the modulation ratio is changed from 1:3 to 3:1.The YSZ films are of cubic phase structure and the SiO_(2) films are amorphous in all the MLs.The change of residual stress in these MLs can be attributed to the variation of an individual layer?s stress with thickness,which indicates that adjusting the thickness ratio of two materials is an effective measure for depositing near-zero stress MLs.
