Investigation of damage in KDP using light scattering techniques
- Lawrence Livermore National Lab., CA (United States); and others
Interest in producing high damage threshold KH{sub 2}PO{sub 4} (KDP) and (D{sub x}H{sub 1-x}){sub 2}PO{sub 4} (DKDP) (also called KD*P) for frequency conversion and optical switching applications is driven by the requirements of the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL). At present only the best crystals meet the NIF system requirements at the third harmonic (351nm) and only after a laser conditioning process. Neither the mechanism for damage in bulk KDP nor the mechanism for conditioning is understood. As part of a development effort to increase the damage thresholds of KDP and DKDP, we have been developing techniques to pinpoint the locations where damage will initiate in the bulk material. After we find these locations we will use other measurement techniques to determine how these locations differ from the other surrounding material and why they cause damage. This will allow crystal growers to focus their efforts to improve damage thresholds. Historically, damage thresholds have increased it is believed as a consequence of increased purity of the growth solution and through the use of constant filtration during the growth process. As a result we believe that damage is caused by defects in the crystals and have conducted a series of experiments using light scatter to locate these defects and to determine when and where damage occurs. In this paper we present results which show a low correlation between light scatter from bulk defects in KDP and the initiation sites for damage. We have also studied the effects of thermal conditioning on light scatter, strain induced birefringence and damage threshold. We have seen evidence that regions of high strain also exhibit lower damage threshold than the surrounding lower strain material.
- Research Organization:
- International Society for Optical Engineering, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 552249
- Report Number(s):
- CONF-961070--Vol.2966
- Country of Publication:
- United States
- Language:
- English
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