高能重复激光脉冲对光学元件损伤点的产生和扩展与损伤点对后续激光脉冲光强的调制作用密切相关。 观察激光诱导K9玻璃的损伤点, 发现损伤点是从里到外呈现辐射状分布, 内部损伤程度最大, 可致充分断裂; 向外损伤程度减小, 呈现辐射的应力相变, 引起折射率变化; 对损伤点的透射光谱检测发现其透过率下降大于20%, 但是下降的幅度与波长无关, 说明充分断裂的材料会对激光进行充分吸收, 类似黑体吸收, 其对入射光的吸收只与损伤点的面积有关。 CCD对激光通过损伤点后的光强分布探测发现: 在激光能量传输过程中, 损伤点会导致光强分布的不均匀, 存在明显的散射效应, 这会引起激光光强分布的不均匀性, 导致损伤区域的进一步扩散。

The production and increase of damage points in optical components under high energy repetitive pulsed lasers is closely dependent on the effects of light beam intensity modulation. In the present paper, the appearance of laser-induced damage points on surface of K9 glass was observed. The damage is increased toward center. In this way, the center of the focus of laser beam is fully cracked, and the shell-like factures and the refractive-index changing region, which is caused by phase transition, are arranged outward orderly. The transmittance spectrum through the K9 glass and damage point were measured, indicating that the optical transmittances can reduce by over 20% and the declining rate is related to the area of damage points instead of the wavelength, which means that the full fracture of the material will absorb laser energy completely and is similar to the black body. The laser density detection with CCD shows that the damage points can cause the distortion of laser transmission and the scattering effect plays a major role. This kind of modulation effects by damage points can cause inhomogeneity of the laser light intensity distribution, which can induce diffusion of damage in optical components.