Fig. 1. Morphologies and size distribution of bulk damage sites in DKDP crystals^[13]. (a) Bulk damage sites in DKDP crystals observed parallel to beam direction; (b) distribution of diameters of central cavities of damage sites; (c) scanning electron microscope (SEM) image of central cavities of damage sites

Fig. 2. Wavelength dependence of laser damage threshold of DKDP crystal ^[16]

Fig. 3. Electron paramagnetic resonance spectra and linear absorption spectra of Cr doped KDP crystals^[27]. (a)(b) Electron paramagnetic resonance spectra of KDP: Cr³⁺_{crystals at room temperature; (c) linear absorption spectra of KDP: Cr³⁺ measured experimentally}

Fig. 4. Images of cross section of KDP crystal^[30]. (a) Light scattering image; (b) fluorescence image under 351 nm laser excitation before irradiation; (c) plasma emission image during single-pulse irradiation; (d) light scattering image after 355 nm pulse irradiation

Fig. 5. Impact of “hair” inclusion on laser induced damage of DKDP crystal^[50]. (a)(b) In-situ dark-field scattering images of crystal when it is damaged; (c)(d) morphologies of damage points in “hair” inclusion test area

Fig. 6. Differential charge diagrams of KDP crystals in different defect systems^[58]. (a) Oxygen vacancies (VO2+); (b) VO2++ potassium vacancies (VK-) + hydrogen vacancies (VH-); (c) VO2++ 2VH-; (d) VO2++2VK-

Fig. 7. Partial densities of states (PDOS) of defect clusters in pristine KDP and KDP crystals^[58]

Fig. 8. Partial densities of states of KDP, K₂H₂P₂O₇ , and KPO₃ crystals^[59]