20 April 1998 Effect of impurities and stress on the damage distributions of rapidly grown KDP crystals
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Development of high damage threshold, 50 cm, rapidly grown KD*P frequency triplers for operation on the National Ignition Facility (NIF) in the 14 J/cm2, 351 nm, 3 ns regime requires a thorough understanding of how the crystal growth parameters and technologies affect laser induced damage. Of particular importance is determining the effect of ionic impurities which may be introduced in widely varying concentrations via the starting salts. In addition, organic particulates can contaminate the solution as leachants from growth platforms or via mechanical ablation. Mechanical stresses in the crystals may also play a strong role in the laser-induced damage distribution (LIDD), particularly in the case of large boules where hydrodynamic forces in the growth tank may be quite high. In order to investigate the effects of various impurities and stresses on laser damage we have developed a dedicated, automated damage test system with diagnostic capabilities specifically designed or measuring time resolved bulk damage onset and evolution. The data obtained makes it possible to construct characteristic damage threshold distributions for each samples. Test results obtained for a variety of DKP samples grown form high purity starting salts and individually doped with Lucite and Teflon, iron, chromium and aluminum show that the LIDD drops with increasing contamination content. The results also show that solution filtration leads to increased damage performance for undoped crystals but is not solely responsible for producing the high LIDDs required by the NIF. The highest LIDD measured on a rapidly grown sample indicate that it is possible to produce high damage threshold material using ultrahigh purity, recrystallized starting salts, continuous filtration and a platform designed to minimize internal stress during growth.
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Michael J. Runkel, Michael J. Runkel, Ming Yan, Ming Yan, Jim J. DeYoreo, Jim J. DeYoreo, Natalia P. Zaitseva, Natalia P. Zaitseva, } "Effect of impurities and stress on the damage distributions of rapidly grown KDP crystals", Proc. SPIE 3244, Laser-Induced Damage in Optical Materials: 1997, (20 April 1998); doi: 10.1117/12.307046; https://doi.org/10.1117/12.307046

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