Analysis of high resolution scatter images from laser damage experiments performed on KDP
- Lawrence Livermore National Lab., CA (United States)
Interest in producing high damage threshold KH{sub 2}PO{sub 4} (KDP) and (D{sub x}H{sub 1{minus}x}){sub 2}PO{sub 4} (KDP*, DKDP) for optical switching and frequency conversion applications is being driven by the system requirements for the National Ignition Facility (NIF) at Lawrence Livermore National Lab (LLNL). Historically, the path to achieving higher damage thresholds has been to improve the purity of crystal growth solutions. Application of advanced filtration technology has increased the damage threshold, but gives little insight into the actual mechanisms of laser damage. The authors have developed a laser scatter diagnostic to better study bulk defects and laser damage mechanisms in KDP and KD*P crystals. This diagnostic consists of a cavity doubled, kilohertz class, Nd:YLF laser (527 nm) and high dynamic range CCD camera which allows imaging of bulk scatter signals. With it, they have performed damage tests at 355 nm on four different {open_quotes}vintages{close_quotes} of KDP crystals, concentrating on crystals produced via fast growth methods. The authors compare the diagnostic`s resolution to LLNL`s standard damage detection method of 100X darkfield microscopy and discuss its impact on damage threshold determination. They have observed the disappearance of scatter sites upon exposure to subthreshold irradiation. In contrast, they have seen scatterers appear where none previously existed. This includes isolated, large (high signal) sites as well as multiple small scatter sites which appear at fluences above 7 J/cm{sup 2} (fine tracking). However, they have not observed a strong correlation of preexisting scatter sites and laser damage sites. The authors speculate on the connection between the laser-induced disappearance of scatter sites and the observed increase in damage threshold with laser conditioning.
- Research Organization:
- International Society for Optical Engineering, Washington, DC (United States)
- OSTI ID:
- 552045
- Report Number(s):
- CONF-9510106-Vol.2714; TRN: 97:005737-0021
- Resource Relation:
- Conference: 27. annual symposium on optical materials for high power lasers, Boulder, CO (United States), 30 Oct - 1 Nov 1995; Other Information: PBD: [1996]; Related Information: Is Part Of Laser-induced damage in optical materials: 1995. Twenty-seventh annual Boulder damage symposium, proceedings; Bennett, H.E.; Guenther, A.H.; Kozlowski, M.R.; Newnam, B.E.; Soileau, M.J. [eds.]; PB: 794 p.
- Country of Publication:
- United States
- Language:
- English
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