大口径KDP晶体折射率非均匀性检测

Measurement of refraction index inhomogeneity of large aperture KDP crystal

KDP晶体的折射率不均匀性将导致光束的空间分布存在不同程度的相位失配,从而使得三倍频系统的转换效率下降。为了得到KDP晶体折射率非均匀性的高精度检测结果,基于正交偏振干涉法,采用ZYGO MST大口径干涉仪,测量得到了大口径KDP晶体折射率非均匀性分布,其测量精度达到10-7,并通过实验研究了晶体面形对测量结果的影响。对晶体e光折射率非均匀性的高精度检测,为大口径晶体材料生长工艺、加工工艺等改进和提高提供了定量的检测依据。

The refraction index inhomogeneity of KDP crystal can cause beam phase mismatch in spatial distribution, thus lead to decreasing conversion efficiency of the third-harmonic genera- tion system. In order to obtain the refraction index inhomogeneity of KDP crystal in high pre- cision, the orthogonal polarized interferometry （OPI） was adopted. Using the ZYGO large ap- erture interferometer, the refraction index inhomogeneity distribution of large size KDP crystal was attained, with the precision as high as 10.7 , the effect of crystal surface figure on the tes- ting result was also studied experimentally. The high precision measurement of the refraction index inhomogeneity of crystal provides quantitative measurement references for the improve- ment of growth and machining technique of large aperture crystal materials.