The optic qualities differ greatly between the inner part and the broadening parts.The transmittance of UV in the broadening parts is lower than that of the inner part and declines rapidly.

• 扩展部分的晶体的光学质量与本体部分差别较大，扩展部分对光的透过率在紫外部分下降很快，明显低于本体部分在这一波段的透过率。