提出了利用偶氮材料的光化学特性制作衍射相位元件的方法。区别于一般的激光直写方法,利用偏振光在偶氮苯聚合物薄膜的表面逐点曝光,结合对光功率密度、曝光时间和光偏振方向的组合控制,以实现每个点的相位延迟量的控制。基于此设想,制作了一系列的相位光栅。利用偏光显微镜和扫描近场光学显微镜(SNOM)观察了光栅的表面形貌,并对实验结果做了定性分析。与相位全息干涉的方法相比,采用的逐点曝光的方法更加灵活,对实验环境的要求不高,有广阔的应用前景。

A novel method for fabricating phase diffractive elements is proposed. Distinguished from the common phase holographic interference,we used single laser beam coming out of the direct writing system to inscribe phase-type gratings. The direct writing system can modulate the intensity and polarization of the Gaussian laser beam. Based on the control ling of the exposure time,intensity and polarization of the writing light,a series of phase-type gratings were fabricated. The induced surface deformation was directly determined by scanning near-field optical microscopy (SNOM). Some qualitative analysis was made in the article. Compared with holographic interference method,the method above is more flexible,undemanding for the experimental condition,which may become a new way of fabricating diffractive optical elements with complicated surface profile and controllable diffractive characteristics.